/diy/ - Do It Yourself

shiny new thread.
This is not one of my projects. this is from a Mastech voltmeter. yes they did this in an actual consumer product.
It's a shitty product all around, but still, that triple stack impressed me a bit.

>>1704668
Could you explain what you mean by rectified mains? Is it just a rectifier running wall power?

here's an idea I have for a variable capacitor
>stacks of washers on a bolt separated by little compression springs
>paper spacers on the washers so they wouldn't short (couldn't draw them in)
>half are connected to ground, half to +
>to vary the capacitance, you'd screw a nut on the bolt down to compress the springs and force the washers closer together

it would have a very low capacitance, though. Maybe there's some kind of cheap, readily available dielectric that I could use to improve performance.

>>1704679
yes, as if you put electricity directly from your wall socket through a rectifier

>>1704681
I'll look into it, thanks pal

>>1704680
really really really low capacitance.
maybe instead of compression springs, use very soft rubber washers that could compress as you tighten the nut. then you might get a usable capacitance from them.

>>1704688
Funnily enough when I was talking this over with my friend, my first go-to was actually deformable rubber rings. Then I changed my mind to the springs.
It's for a diy transistor AM radio which needs a ~415 pF variable capacitor, so it doesn't need terribly high capacitance.

I'll probably make both for shits and giggles

How were keyboards for old analog synths made?
I can't really find a whole lot of information, most designs either use button matrix and a microcontroller, or are just plain voltage dividers for using with a 555 timer.

This was my best attempt.
The diodes are there so that if multiple keys are pressed, only the highest key will play.
The 20MΩ resistor is to simulate the input current on a real op-amp.
It kinda works, but there's still a 50mv drop across the diodes, which is like half a note when using 1V/Octave, so not that great.
Obviously I could remove the diodes, turning it back into a regular old voltage divider, but then you get weird notes if multiple keys are pressed.
Another solution would be to replace all the diodes with ideal diodes, but that adds quite a bit of cost to the BOM.

>>1704701
they didn't use the diodes

>>1704680
>>1704694
Any reason you don't want to use the tried and true design of semicircles that rotate in and out of a fixed bank of plates?

I've seen people make these out of tin foil and paper in a CD jewel case

>>1704704
Whoops, image

>>1704703
So you just got weird notes halfway between the pressed keys if multiple keys were pressed?
That seems like a pain to deal with.

I guess if making anything more advanced than that requires a microcontroller, I might as well just skip making my own keyboard and make a MIDI to CV converter instead.

>>1704704
>>1704705

Just for the sake of trying something different and making something new. Honestly, I was going to make one of those semicircle capacitors as well

Does anyone know if SnPb solder will work with zinc at all?

>>1704708
Well, points for trying something new.
I'd be surprised if that hit much more than a picofarad of capacitance though.

Might be interesting to adapt that to being a variable inductor though.
Make is such that you have a spring fixed on one end and free to rotate on the other, then as you rotate the free end you add more loops and make the coil tighter, thus increasing the inductance.

>>1704679
>>1704681
And a filter capacitor. In this case I'd be tempted to stick with a single-diode instead of a full-bridge, for ground reference reasons.

>>1704680
the springs would "short" the electric field, unless you made them out of plastic. Also pretty sure some primitive varicaps already work like this, though only with an offset spring-loaded metal plate as the top electrode held down by the screw that pulls it closer to the base with an insulator in between.

>>1704694
What matters more than absolute capacitance is the ratio between minimum and maximum capacitance, as it equals the maximum ratio of the highest to the lowest possible tuneable frequency. Furthermore, 400pF is actually pretty high for a variable capacitor, it's most common to get single plate models from 5-70pF, while decently-sized rotating multiplates get up into the ranges you're talking about.

>>1704717
>as you rotate the free end you add more loops and make the coil tighter
Sounds like copper fatigue in the making. Isn't it more conventional to just move a ferrite core in and out of a solenoid?

>>1704720
>the springs would "short" the electric field
Do you mind elaborating? I'm not sure if you mean an actual physical short from metal-on-metal contact (I plan on having the washers covered in paper so the springs don't have any way of shorting the washers), or if there's another effect the springs would have on the field due inherently to their presence

not related but I should also explicitly state that I plan/imagine that the inner diameter of the washers would be sufficiently large enough that they would avoid shorting against the bolt itself

>>1704720
>Sounds like copper fatigue in the making. Isn't it more conventional to just move a ferrite core in and out of a solenoid?
Obviously. It's not a great design, just another novel/unusual way to make something.
That said, fatigue may not completely be an issue.
Clock springs wind and unwind day in and day out, so you could try scavenging a mainspring to make such an inductor.

How do I make this thing stop beeping every time a button is pressed? It's insanely loud. Can I just find the piezo buzzer on the circuit board and cut it off? Would I need to replace it with something that has the same resistance?

>>1704707
one, git gud. why would you press more than one key at once on a monophonic keyboard if you didn't intend to? when there were arpeggios to be played they generally used an analog sequencer (CD4051, 555, and a bunch of pots)
two, never try to second-guess an analog synth artist about "weird"
>MIDI to CV
this is probably the most generally correct answer

>>1704728
sure, that'll work
no, you don't need to replace it with anything

>>1704730
>why would you press more than one key at once on a monophonic keyboard
To glide between notes is a common use.
Most monophonic keyboards I use put a glide between notes if you press one key and then press another while the previous is still held down.

>never try to second-guess an analog synth artist about "weird"
Well, I won't debate that, but I prefer any weirdness in my patches to be by design, rather than an issue in the equipment used.

>>1704733
>To glide between notes is a common use.
you're doing it wrong. you add a slope limiter in the CV chain to do that
"real" CV/gate keyboards also post-processed that output with a key-down detector and a sample and hold stage, mostly to hold the CV during the release phase. the sample and hold could be made a little leaky if that suits you
>most
you sure they're not MCU-based?
>issue
it's not a toomah

>>1704721
Consider placing a block of metal between a simple capacitor's plates. This turns the assembly into two capacitors in series, one from plate A to the block, and one from the block to plate B. There can be no electric field inside the block itself because it has a resistivity that might as well be 0 compared to the voltages we're talking about, so the electric field in this case I would describe as being shorted. In the case of a small spring it's less black-and-white since you'd basically need to integrate over the area divided by the displacement (squared?), but either way I suspect the spring itself will make a significant contribution to the integral. Even though the spring has a significantly smaller effective area, it's a fractional millimetre away from both plates, while the distance from the plates to each other is going to be significantly higher.

>>1704722
I was going to argue that the turns would short as it got wound up enough, but then again shorting turns would mean lower inductance. But would a radially-wound torsion spring have enough turns to work at all? I'd prefer to go for a cylindrically-wound torsion spring, but I think those usually have shorted windings anyhow, so you may need to stretch it. Considering the pulleys and gearboxes some old equipment pieces had connected to pots and trimmer caps, these suggestions aren't really that strange at all. In fact my function generator has a compact gearbox inside the frequency knob itself that steps down for finer adjustment in the frequency-adjusting potentiometer.

>mfw I could have had boards in time for this weekend if only I'd not chosen blue solder mask

Wtf why do I have so many of these, I don't even do electronics

>>1704812
Put them away and get the real one.
It survived 13kV fully functional.

>>1704818
idk man not feelin too good about those weird chink letters

>>1704833
Ask google translate what a 福禄克 is.

fucking USPS screwing me again. they told me for sure Friday would be delivered, then "whoops its going to be late" see you saturday.
I just want my new belts so I can work on the VTR again bros, its been sitting there for a week now.

>>1704889

Thanks for the update. I was worried.

Keep us posted every hour or so if you can.

I'm searching for a word I havent managed to figure out in english yet.
What do you call the following row of values?
>1 2 4 8 16 23 64 ...

>>1704900
Non-proofread

>>1704900
>What do you call the following row of values?
not a sequence

>>1704900
greentext

>>1704904
I actually paid extra attention to write 32.

>>1704909
>32
https://oeis.org/search?q=1+2+4+8+16+32+64&sort=&language=english&go=Search

>>1704909
I understand Anon, I've posted things that I KNEW were right, then... Arggh! Anyway, sequence, series, progression? Try one of those.

So, when you distort a sinewave you harmonics of your input signal. We all know this. But do you also get subharmonics? Like, if I symmetrically clip a 1kHz sine wave I get 3kHz, 5kHz, 7kHz, etc components but do you also get odd order subharmonic distortion. 333Hz, 200Hz, 143Hz, etc? If not then how do you produce subharmonics of a signal? Reflections creating standing waves?

>>1704910
>>1704919
Thanks. You helped me figure it out. Its powers of 2

Can anyone help me with the keywording to be able to find a connector exactly like this?
Nearest I could find was "Mini B smd 180" but I'm not seeing the exact style anywhere

>>1704943
"Mini B smd vertical" seems to work for me

>>1704947
im not seeing any with the big plastic base though. the overall length matters a lot

>>1704956
Looks just like my second result.

>>1704943
been out of production for like a decade. time to pay $5 to the ebay scalpers listing them as 'garmin nuvi usb'

>>1704966
>>1704980

link?
the second one there I cant find for sale but I found some site saying stuff about it

I dont really care how much it costs

>>1704900
evidence of dyslexia

>>1704923
not usually, unless something in your circuit is resonant at those frequencies and being excited into producing them. in analog synthesis you'd typically add them explicitly, separately

>>1704900
pro tip: exploit the cognitive hack of negative learning. write out the *wrong* series several times for practice and make sure it's wrong

>>1704680
Your idea is essentially the same as >>1704705.
The real one is however multiple +/- plates while your idea would be two singular corkscrewed plates.

In a foil or electrolytic capacitor, the foil layers are parallel to the central axis rather than perpendicular.

If you didn't need a smooth taper, you could stack layers and electrically add or take them away with a wiper.

>>1705070
Actually a spiral design like what's inside electrolytics, but with a plastic shaft in the middle that rotates could be a pretty nice design. Though the plate holders/electrodes on either end (the dots in this image) would need to be able to move in and out, probably with a light preload. The shaft itself might need a preload in the opposite direction to stop the thing from unwinding itself. Or you could make the plate holders on a geared mechanism that move in and out in time with the central shaft, but I suspect the springs would be significantly easier. I suspect you'd be able to go from very low capacitances to somewhat high capacitances, depending on your flexible plate material and how well it can bend.

If I wanted to drive one of those cheap Class D mono amplifiers out of a phones headphone port, I have to use a stereo jack because otherwise a mono jack would constantly short gnd and right channel right?

Also what would happen if I tried driving one of those cheap amps way above line level, like 10v rms (30vpp)? pic rel for example says max 3v but doesnt say if peak or rms.

>>1705290
Yes? Ideally the phone may be able to detect such a condition and switch to mono in the same way it can detect whether you're using TRS or TRRS headphones, but I doubt it. Give it a try with audio that's got different frequencies on each channel.

>>1705290
Actually combinding stereo into mono is pretty easy i think you just need some resistor
or you can get an audino jack female and connect only two wires from it to that amplifier so one of the stereo channels is not connected to anything

>>1705299
I think the problem is that he's trying to get mono out of an existing phone's socket, so he can't put any resistors between the phone's amplifier and the mono cable. And only connecting one of the two channels would sound worse than averaging both channels, right?

How hard is to solder this?
Those pads are sooo tiny

>>1704680
It's not failure, it's just another method that doesn't work.
Keep at it! You can do it. Document your work.

>>1705309

external flux will magically deposit (move) the solder only where it should go, so you can use any size, any shape tip, and it'll work beautifully. watch SMD soldering related youtube videos to see the magic at work.

>>1705347
>external flux
my solder has flux inside of it is that enough? i also bought a cain of rosin if that counts but it's basically a piece of rock

>>1705359
>piece of rock
Acetone or ethanol work well as solvents.

>>1705370
>Acetone
not sure if breathing in acetone rosin solder fumes is such a great idea

>>1704678
They must have mass procuced it, right? How to you manage to automate that?

>>1705373
biobots

>>1705359
>is that enough?

you need like 20 times the internal volume for the magic to happen.

>>1705373
THTs are usually hand soldered by insectoids so and it seems to me they had a lot of extra smds they wanted to use so they slapped them in parallel like that or wanted higher power dissipating capability, since pick and place bots can't stack smds like that

>>1704672
Hey, how can I start working on electronics? I have no clue how to make something that actually does something. I can make a lightbulb glow and that is about it.

>>1705397
you're apparently incapable of reading the OP, let alone the datasheets of any components you will ever use. you are already proven incapable

>>1705397
start with an electronics education toy like pic related; it's fun even if you don't end up learning anything. (don't spend more than $30 used, and make sure you get the instructions)

I have a question for anyone familiar with video game consoles. Recently my Nintendo Wii (purchased in 2006) encountered issues with playing discs. I opened the whole thing up, dusted it out, cleaned the tech with 98% alcohol and q-tips, and put it back together. The console will at least recognize Wii discs I put in, but when I choose to play a game, the Wii will either get an error message after loading the initial company logos or outright crash. However, sometimes it will actually boot up the game, but if I have to pause or cross a loading zone, the game will freeze and the Reset button won't work.

What's odd is that Gamecube discs work just fine. I can play any of those and the Wii won't encounter issues. It's only for Wii discs, and no fix-it guide online seems to address this issue. Do I have a lens issue or a motor issue related to disc size? Can the lens be fixed if Gamecube discs still work, or do I have to purchase a whole new lens/console?

Thanks.

>>1705451
take your consumer product shit back to /g/

>>1705371
acetone on its own is fairly harmless it just smells terrible. Rosin on the other hand is the other way around if im not mistaken. fairly abd for you but smells not too bad

>>1705309
You'll probably need hot air to get that bottom pad, but arguably you could put a little solder paste on it and reflow it from below (once the edge pads are soldered in place) if the vias there are dense enough. But I can't see any vias.
Soldering the edge pads would actually be a piece of cake, just use plenty of flux and run a bead on a slightly hotter than usual iron down each side. It may take multiple attempts in order to get the right amount of solder with no bridges, but the concave edge pads on the ESP modules should give you a bit of leeway. Grab an SMT practice board and see how you go, or perhaps a handful of breadboard SMT breakouts and some ICs you're likely to use for something a bit more practical. Like D-FFs, shift registers, or a CXD9981 mystery chip.

>>1705370
That's not how you spell isopropyl alcohol. I hear bad things about acetone as it can dissolve other things that may be present on your board, perhaps including solder mask. Never heard of anyone using ethanol, I'd avoid it as it evaporates much less readily than IPA, though this could make it better for scrubbing PCBs without having to constantly add more solvent. Rosin doesn't make fumes unless it's burning, it isn't volatile at all.

>>1705521
I've found cleaning with IPA tends to leave a white residue around pins typically and the board will also be sticky after washing and it does not go away. I can't imagine what the white substance is, it's probably from something in the flux reacting with the IPA and precipitating out but it looks as if it might be corrosive.

I do not have any of these problems with acetone.

After two weeks the new rubber belts arrived...and they actually made it worse. With the new belts the motors were struggling to move and I was getting this constant banding while the video was playing. putting the old belts on made it go back to normal.
back to square one. next step is to wait until the frequency counter arrives so i can fix this color issue once and for all.

Found this little guy digging through my high school shit

>>1705523
I've had success using IPA + kimwipe + acid brush to remove the bulk of the flux residue. then, before it dries, I follow up with CRC "QD" electronic cleaner, sold in auto parts stores and consisting mostly of hexanes and ethanol, sprayed sparingly onto a board and under QFPs and then scrubbed with a toothbrush, rinsed off with IPA in a spray bottle periodically, finished by a hot water rinse. it's super effective, even against Ersin 362. google around to see what a bitch that stuff is if you're not familiar
at some point I intend to get a can of ethyl acetate and try combining it with some IPA, maybe add some other primary alcohol. should work great for rosin fluxes. we'll see about the no-cleans
or I could just say fuckit and try this. 6 oz. can only $14.88
https://www.digikey.com/product-detail/en/chemtronics/ES896B/75-ES896B-ND/10244092

>>1705534
looks like an astable multivibrator

>>1705572
That sounds like a lot of effort and money on supplies when I can just use acetone and get equally good results.

>>1705575
if you like cheap, you'd be surprised just how well 75°C hot water sprays work if you're not allergic to a bit of elbow grease

here's your 5V/1A Li+ UPS on a chip, faggots

>test new 10nF HV caps with existing 220µH inductors
>peak frequency at 110kHz
Power line communication here we come!
Actually is there a way of testing the maximum voltage of these noname inductors? Not that it matters for the most part because the inductor will be shorting the mains (at 750µA through the 10nF cap) to ground, but for voltage spikes or high-amplitude switching noise I may need to worry. Good thing I have a spare MOV rattling about for anything above mains.

my "Saleae" logic analyzer knockoff failed to save me a couple of hours this evening. because I didn't use it. I thought I was being so clever and forward thinking, setting up that USART for even parity and promptly forgetting I did. Pic related

>>1705678
>maximum voltage
there isn't really one. inductors deal in current
>a way
not really. you might be able to make some stupid estimates of power dissipation for the series LC and its parts over frequency and judge whether it's reasonable for the package

>>1705695
>there isn't really one
A high enough frequency will cause the inductor to behave as an insulator, and it will have a breakdown voltage based on its enamel insulation, and this will also depend on whether/how the windings overlap. Pretty sure the only way of testing it would be with a high-frequency high-voltage power supply, or perhaps slapping it in a high-Q series LC resonant network and watching the voltage climb as you drive it.

To prevent ic resets from relay switching am i supposed to put the ferrite cockring on the load wire or the IC wire controlling the relay?

>>1705709
oh, sure, all bets are off above the self-resonant frequency

>>1705721
draw schematic

>>1705722
generic relay usage except the load is inductive

>>1705605
>UPS on a chip
No, output shuts down on charge, no feedthrough.

>>1705724
That relay board already has a switching transistor, the actual current to the base/gate of the transistor on the signal wire will be minimal, so no point in slapping a ferrite on that. The board has a ceramic cap presumably across Vcc and GND, but you could improve this by adding a bigger (100µF?) cap in parallel with these lines close to the board, at least I'd do this before adding a ferrite. Then adding a ferrite between the arduino and this capacitor might do some good, but I'd probably ignore it.

74HC schmitt trigger logic ICs have about twice the propagation delay (15ns) as 74HC logic ICs with no schmitt trigger (8ns), should I still go for them? Or will the 4000 series or other common logic series offer me better speeds?

>>1705740

HC stands ''High Speed CMOS.'' kinda answers your question. and if that's not enough, you can ask the all-knowing oracle known as The Datasheet.

>>1705740
Maybe 74F would be a faster logic type, but it consumes a lot of current.

my sony str-dg700 amplifier keeps clicking out in use, although the subwoofer continues to work. I assumed the capacitors in the speakers were faulty and causing a short so i disconnected them, as well as the tweeters which have been non functional for some time.
It still keeps clicking though. what should i do?

Voltage divider has non linear transfer function. Anyone knows a good circuit to linearize it? Like for panel control knob shit.

>>1705868
Just use a biode or transratiometer

>>1705735
fug. removing from LCSC cart

>>1705740
>4000 faster than HC
kek
you wouldn't notice
>should I still go for them
no, hipster discrete logic systems are dead

>>1704710
Just buy some silver solder.
It works well with brass, steel and other non copper metals.

>>1705868
nonlinear in what regard? if you're worried about the variable output impedance then buffer it with an op amp.

>>1705873
I remember that guy hehe
>>1705897
voltage divider := (x/x+a), for audio volumes this is ok but I'd like to control a voltage output and it needs to be fairly linear or atleast the user has to be able to make fine-ish ajustments on the whole range.

>>1705877
>no, hipster discrete logic systems are dead
t. zoomer whose prototypes are made in china kek

>>1704672
Can one of you EE chads please help me out.
I'm teaching myself electronics through an EE textbook - these formulas for AC power are confusing me.
I get that RMS needs to be used for P=V^2/R because it's gonna be the mean of all the V^2 values. But why the fuck are RMS values used for P = VI? There are no squares? Why would you use a mean of the squares when neither of the values are squared? Shouldn't it just be the mean of the normal (unsquared) voltage and current?

>>1705915
>t.boomer whomst'd've THTs and can't even see an 0201

>>1705913
>t.too homosexual to figure out a potentiometer

>>1705916

there's no relationship between RMS and the squaring of the voltage and current values to calculate power.
- RMS is needed coz if you simply average a sine, you get zero.
- the squaring of voltage and current in calculating power occurs from simple substitution of terms from ohm's law in the basic P=EI formula. e.g. if you replace I by it's equivalent in ohms law of E/R, then you get P=E*E/R or E^2/R

so, zero relationship to RMS.

>>1705916
P=V*I regardless of these values being RMS or not.
V/R=I, so P=V*(V/R) aka P=V2/R

>>1705916
> But why the fuck are RMS values used for P = VI?
P = (1/T)*integral v(t)*i(t) dt.
= (1/T)*integral (V*sin(ω*t))*(I*sin(ω*t)) dt
= (1/T)*integral V*I*sin^2(ω*t) dt
= V*I * (1/T)*integral sin^2(ω*t) dt
= V*I * (1/T)*integral 1/2-cos(2*ω*t)/2 dt
= V*I * (1/T)*(T/2)
= V*I * (1/2)
= (V/√2)*(I/√2)

Mean power = 1/2 peak power. This is why AC voltage/current are specified using RMS rather than peak. If both voltage and current are specified as 1/√2 of the peak value, then all of P=V*I, P=V^2/R and P=I^2*R get two 1/√2 factors and the result is the mean power.

If you evaluate the actual power as the integral, then any of any of V*I, V^2 or I^2 have a sin^2(ω*t) factor.

I have a BSEE from years years ago and work in industrial automation. Thinking about switching to a career in embedded or hardware but it's going to take forever to relearn everything - I honestly forgot so much from school.

Anyway I'm putting this kit together and it's going pretty well. Just wish I had a signal generator and o-scope to get the most out of it. I forgot how bad I am at soldering. It was a cozy Saturday putting this together, though.

>>1705877
>hipster discrete logic systems are dead
do shift registers and bus transceivers and counters count as discrete logic?

>>1705950
Thanks very much anon, I think I can follow all of this.
I see why everyone makes fun of the term "software engineer" now though, fuck, I'm a final year CS undergrad and trying to get my head around all these EE proofs is hurting my head more than anything on my course ever has, kek.
With EE is it best to just accept stuff as fact without question most of the time? My brain always wants to know exactly why stuff is the way it is but then I get sucked into rabbit holes of looking at proofs for hours, I've been trying to understand this for at least 2 hours now when I could have just written it down as fact in 5 seconds after reading it in my textbook and moved on.

>>1705972
>With EE is it best to just accept stuff as fact without question most of the time?
yes, the fundamental math and principles of operation for common systems that you read will all be objectively correct. suppliers like TI even go out of their way to explain helpful theory in their datasheets. at a certain level of expertise you'll need to understand why things are true, but you can generally take them for granted.

>>1705970
systems. if there are more than four discrete logic gates in one signal path at one time, it's time to get suspicious

>>1705978
Alright cool, that's good to know.

>>1705950
Follow up question if you don't mind, as you've shown the reason for RMS can be proved, but at a high level is the reason we use RMS basically just because every power equation has a V^2 or I^2 in it? I was getting confused because RMS is apparently used in stats but I think that's just a coincidence right? RMS in electronics doesn't have some magical statistic property, it just happens that since the formulas use the average of square values we end up with it?

>>1705993
>at a high level is the reason we use RMS basically just because every power equation has a V^2 or I^2 in it
Not really, but I wouldn't call it a coincidence either. Practically speaking, consider a load resistor across a voltage source. If it's straight DC, then the average power dissipated is equal to P=V(DC) = V(DC)^2/R. Power is something practical and easy to quantify, or rather, it's the derivative of energy that we're quantifying. Now considering any arbitrary waveform voltage, we want to find some way to measure this voltage to give us a useful quantity, namely the equivalent DC voltage required to dissipate the same amount of power in the same resistor. For a sine wave this happens to be V(DC equivalent) = V(RMS) = V(peak)/√2, but for a square wave it's V(peak)/2 or V(peak)*duty-cycle, for a triangle wave it's something else again. So you could say it's a quirk of the physics of the V^2 relation, but I'd be more likely to say that it and the V^2 relation are quirks of geometry and calculus.

>>1706002
Hmmm ok, makes sense. I think it's best that I just accept these equations as true and move on, I understand them a lot better now but I still don't have total clarity, but I think if I go through learning electronics trying to understand the proof for every little thing I'm still going to be stuck on beginner stuff for 30 years.

How do measure? Scope can handle 400Vpk so I'm not worried about damaging my scope from overvoltage, but this neutral/ground reference thing seems to be problematic. Unless I can put a 10nF across live to ground without tripping the RCD. Thoughts?

>>1706024
lift the ground of the scope and don't touch more than one thing at a time while working on this

>>1706035
I'm first trying it with the probe across the filter output and ground (not neutral), but I'm getting some 50Hz noise, looks like it's from a triac somewhere. Considering it's making it through 3.3 decades/~130dB of attenuation it must be really high-amplitude, or otherwise it's busting through my filter some other way.

>>1705290
>driving one of those cheap amps way above line level
you'll get distorted/clipped output
worst case it goes square wave and melts the voice coils of whatever speakers you're running

>>1706043
I'm seeing a bunch of frequencies in here, one of them might possibly be AM radio at 975kHz, which is somewhat promising. It's also giving occasional noise spikes, I may try to capture one of these to see what components they have.

>>1706049
140ms of noise, boy is this digital mode handy. Looks to be noise in the realm of 1.1kHz, but it's too close to my nyquist frequency so I'll have to zoom in with the next capture.

>>1706056
Now THIS doesn't look like noise anymore. But since it's so infrequent it probably can't be the action of a SMPS, and likely isn't a hot water cylinder or refrigerator turning on. It could conceivably be a battery charging circuit (phone, laptop, etc.) starting and stopping.

Are there any breadboards that don't suck or is that just the nature of the beast? The one I've got is from I chink arduino kit thing I was given as a gift and it's fucking garbage. Always have to wiggle and press on components to make connections.

>>1706147
Newer breadboards are definitely a little tighter than well-used ones, but from what I've heard they're all the same. Unless you go for some obscure and obviously different model. Consider using thicker leads and jumpers, the leads from 1N4000 series diodes seem to be the perfect thickness for breadboarding, though I can only use them for short-range jumpers. Some resistors have thicker leads than others (possibly the proper tin-plated copper ones?), so you may be able to specify only those when next you purchase passives.

Why do I do this to myself, I could simply use solder for this, but I can't bring myself to do it. To top it off I bought stranded by mistake when I meant to get solid.

>>1706059
>too infrequent to be an SMPS
not if it's powering some device in sleep mode. the cheap-but-not-too-cheap ones just turn the primary side on/off via an optocoupler when the voltage is too low/high

>>1706147
you get what you pay for. Pic related are tolerably good

>>1706165
Well after leaving my scope waiting for a trigger for 20 minutes I never received another one, so if it's turning on via negative feedback, the feedback buffer has got to be pretty large. But judging by the waveform I'd say it's more likely to be actual data getting backfed than any sort of power supply. Which leads to the question, what method of transmitting data is the best at accidentally backfeeding into the mains?
I also have a few doorbells (one of which is on a momentary light-switch) that it could conceivably be, so I'll test that tomorrow maybe. In fact that might be how those doorbell receivers that plug into mains work.

>>1706174
what's wrong with ringing doorbells in the dead of evening solely for science?

>>1706174
streetlight switching/off-peak load control (zellweger) would be my #1 suspect since it's deliberately fed into the mains, but that's supposedly down in the 1kHz

>>1706156
>I bought stranded by mistake when I meant to get solid.

you mean you dont have some extra ethernet cables you can cannibalize for 24AWG solid wire? a 5-foot cable will give you 45-ft of hookup wire, good for a dozen projects, and even some left over for erotic asphyxiation.

I need to replace my cooling fan in my laptop. I already bought the replacement, but it's part of the heatsink piece, so I need to reapply thermal paste and replace a tape that seals any flow to the inside of the laptop.
I have 2 questions:
Is normal alcool (pink) good to clean the thermal paste or I need the white one?
I need an advice for the thermal insulated tape: the max temp are 100 celsius degree, and even if there's a temperature gradient in the heatsink pipe, I'd like a tape that can withstand 100, so could you suggest me one?
Thanks

>>1705970
Just get an MCU with more GPIO pins.

>>1706297

the role of the alcohol is simply to wet the tissue or rag so that it grabs the bits of crud better. so, most any liquid will work. alcohol is chosen of course, coz it evaporates quick.

Dupont's kapton tape: ''They have been used in field applications where the environmental temperatures were as low as -269°C (-52°F) and as high as 400°C (752°F)''

Ordered 2 MG995 servos months ago and never got round to using them for anything.
So I literally just opened the pack today (They both came together).
Hooked one up and tried to get it to sweep back and forward by about 60 degrees.
All it did was constantly spin in one direction (like a normal DC motor).
I tried to just set it to a fixed point but the same happened.
I plugged the other one in and it worked fine.
Now I've noticed the bad one has what seems to be a trimmer pot on it.
Anyone know what the fuck is going on?

What is this thing called? I would like to be able to interpret this style of diagram.

Sources:
>https://www.convexoptimization.com/wikimization/index.php/Dattorro_Convex_Optimization_of_a_Reverberator
>https://ccrma.stanford.edu/~dattorro/EffectDesignPart1.pdf

>>1706333
You got chinked.
The one with the pot is modded for continous rotation. It basicly is a DC motor with a gearbox now.

>>1706353
Weird, I ordered it from a place in England that has a physical store

>>1706349
that's a data flow diagram which has not a thing to do with electronics. go ask the code heads on >>>/g/

>>1706368
"Continuous-rotation servos are servos that do not have a limited travel angle, instead they can rotate continuously. They can be thought of as a motor and gearbox with servo input controls. In such servos the input pulse results in a rotational speed, and the typical 1.5 ms center value is the stop position. A smaller value should turn the servo clockwise and a higher one counterclockwise."

/amg/ guy here, I've only worked with 18650 and Lipo batteries before and for charging I use those TP4056 modules.
Now I need to use a lead-acid battery pic related, and don't know if is there an IC to charging it or I just need to deliver it current at a constant voltage

>>1706375
>has not a thing to do with electronics
Have you never done anything with signal processing or control systems?
Data flow diagrams are very common for those, since they're made to model common analog building blocks.

>>1706429
why yes I have. that's discrete-time comp sci, not continuous-time electronics
>model analog
but are they analog? no? thought not
this isn't a catchall general for "shit with lines or wires". >>>/g/

>>1706298
but then I can't do that really cool hardware cyclic redundancy check

>>1706225
The smallest wave in that image is around 10kHz, but the individually resolvable peaks in the first 5ms seem to be at a frequency of somewhere near 1kHz, so it could well be suspect. But I don't think the time at which I measured that (3pm) would coincide with off-peak load switching. I'm more wondering why the two frequencies seem to be mixed together.

>>1706426
>I just need to deliver it current at a constant voltage

say the battery is pretty dead, it's reading 2V. you hit it with a constant 13Vdc, so the current is (13-2) divided by 0.2 ohms of internal resistance, with equals 55A. is that a sane thing to do?
fortunately googling ''charging an SLA battery'' returns 3 billion results, only 1 billion of which were written by insane people.

>>1706447
get a micro with built-in CRC then

>>1706452
looks a little bit like IRIG

>>1706454
Understable have a nice day

>>1706461
>looks a little bit like IRIG
Ooh you might be right, I'll see if I get another one in 2 hours' time

>>1706232
I do, but I'm too lazy to tear the massive spool I have up in the attic that's being used to route my line. It's got like an extra 150ft on it.

Can someone reccomend me a good assorted capacitor set? I dont know what size/type are most common. im a beginner trying to build simple audio related circuits and maybe guitar pedals or analog synth modules.

Its not V = I x R
It only looks commutative because of the algebra but actually without voltage there is no current so technically speaking its I = V / R which makes logical sense, Voltage divided by resistance = current

>>1706533
Actually resistance is the key element bc without resistance there is no voltage. So R=V/I

>>1706546

You are joking
10V / 0 ohms = 10 Volts

electrostatic potential is voltage without current or resistance.

>>1706426
it is almost certainly easier to use an IC to do it. google "lead acid charger IC" for lots of interesting parts and application designs from IC manufacturers, very few of whom are insane

>>1706525
you'll need more than one. get ceramic caps for the high capacitance per unit volume, get greencaps for better stability against environment, get some electrolytics for signal coupling and power supply filtering
you probably won't need a kit with more than 10-20 of each value

>>1706548
10V across 0 ohms is Big Bang-tier current
also you misspelled "infinity ohms"

>>1706548
But 0 resistance the voltage difference would reach be spent instantaneously

>>1706533
And in a circuit with a current source it becomes V=I*R. Which of the variables are dependant and which ones are independant depend entirely on circumstance, and in any practical situation you never have a perfect voltage or current source anyhow so you have to compromise. Even still, Thevenin and Norton equivalents are both perfectly valid ways of considering a circuit. The takeaway is that the order that an equation is arranged isn't indicative of some sort of natural order of precedence, or anything at all. In this case, historically speaking, resistance R was defined by Ohm to be V/I, but that's just historical finnagering, and again this order of how it's written implies nothing about the relationship itself. You are to rearrange the formula as you see fit. 3/10 made me reply.

>>1706546
This isn't correct, voltage is a measure of the potential energy per unit charge and exists without the need for any definition of current.

>>1706548
>10V / 0 ohms
That's a wonderfully misleading statement. I to think you meant to say "infinity ohms".

>>1706549
>greencaps
What specifically do you use those for? I've only ever used them for higher voltage non-polar applications. Ceramics these days go up to 1µF, and anything above that I'd only use for DC noise filtering, i.e. cases where electrolytics work. I prefer my impedances large, I suppose.

>>1706626
>greencaps
they're not microphonic and their capacitance is more stable with temperature and dc bias. important if trying to build a VCO, though better options exist
>ceramics these days go up to 1µF
>t.through-hole boomer

>>1706632
>through-hole boomer
It was a conservative estimate from someone who only ever buys cheap parts off alibay. You're right though.
>a VCO
Aren't those going to be stabilised with a PLL or some other feedback system anyhow? Are there cases where people use discrete VCOs without frequency feedback ever?
I can understand where increased temperature and DC bias comes in handy in general. Will a THT disc ceramic exhibit microphony? Because that sounds like a fun demonstration.

>>1706633
I bought my most recent roll of 22µF 16V caps from alibay a couple years ago. they're very handy for putting buck converters into a finished project
>Aren't those going to be stabilised with a PLL or some other feedback system anyhow
anon asked about audio applications. so, probably not
>Are there cases where people use discrete VCOs without frequency feedback ever?
yep almost every analog synth (with the notable exception of the Prophet-5, which had a unique self-tuning feature but you had to stop playing for a sec to use it). with shitty drifty caps and generally uncontrolled manufacturing processes of ye olden days, it was not unknown to post a tech behind the keyboardist to adjust the tuning during a song, which is a sort of manual feedback I guess
>THT disc exhibit microphony
it's very possible. the similarities to a piezo disc are remarkable. hook it up like a condenser mic element and see what happens. the temperature-stable C0G caps aren't microphonic, but they're hard to find much above 1n
>eyes the Murata 104 50V Z5V from my childhood

>>1706643
>audio applications
Oh like VCOs in synths or guitar pedals? That makes some sense, yes. I'd quite like to be messing around with that sort of thing, but I'm allergic to Colpitts oscillators.
>hook it up like a condenser mic element
I tried hooking it up like an RF mic to see if I could see the amplitude fluctuating (I don't have a proper DC power supply at the moment) but I couldn't, at least not without rectifying and filtering it.

I think I'll look into making some sort of convenient setup to use with this 12V 1A power brick I got for $4, I have a couple of banana binding posts and a spare LM2596 module. No actual banana alligator leads though, besides the ones that fell apart after using with my DMM for a few weeks. It should beat using my laptop's 5V USB output.

>>1706652
What does a Colpitts oscillator do in a guitar pedal?

>>1706660
It's more for VCOs in general. At least the sinusoidal ones, I guess analog synths don't care too much about having a sine wave. In guitar pedals I guess anything with a tremolo, or otherwise use of a frequency mixer.

>>1706661
I've never seen an LC oscillator for audio frequencies unless two for mixing like in a theremin. Normally audio uses RC circuits. Tremolo is AM and vibrato is FM, right?

>>1706652
at audio frequencies it's usually solid-state such as this sexy bitch, or an op-amp-based circuit along the same lines. or the Latvian clone of the sexy bitch

>>1706661
if you want sines you generally put a nice 4th-order VCLPF on the output
in the case of a ring modulator they usually just use a triangle wave and swallow the harmonics as extra brightness

>>1706664
correct

>>1706664
>I've never seen an LC oscillator for audio frequencies unless two for mixing like in a theremin.
Thhere's a thing called the Beat Frequency Oscillator. The BFO.
Two high frequency oscillators, one fixed one variable, modulate to produce a difference frequency.
Actually, modulation produces lots of products; the BFO uses the lower frequency output.

>>1706675
Example: Q41 is the VFO, Q11 is the BFO (both Colpitts oscillators) and Q21 is the mixer or product detector. One of the products is the audio frequency.

The ethernal question: Powering electronic projects with batteries.

Obviously li-ion cells are desirable, because they have a high energy density. Also they are basically small explosives if you don't know what you are doing for the same reason.

I wanted to power a Rpi + screen with li-ion cells, so I figured in order to not build a bomb I'd use a BMS. Now all the BMS I've seen say that you should keep the wires from the battery to the BMS as short as possible, but I want the batteries to basically be in one line, as if they were in series, but I won't connect them in series, because that means I can't control them via the BMS effectively anymore. Pic is a shitty drawing about what I mean. Would this result in issues? Why do they want the wires to be so short? Since it's DC I fail to see how wires could make that much of a problem (obv the wires need to be of adequate diameter to support the current, but that's it right?).

If the whole idea is retarded, what else should I use?

>>1706626
> and again this order of how it's written implies nothing about the relationship itself. You are to rearrange the formula as you see fit. 3/10 made me reply.

Precedence is everything, If you think you can arrange any formula as you see fit without looking at precedence you are wrong.

There is no commutivity, Its a special case.

Addition and multiplication are "commutative", add them together and they are not.

2 + (3 × 4) = 14
(2 + 3) × 4 = 20'

>>1706417
So seems it rotates at the same speed clockwise regardless of what I set it to

>>1706817
Does this potentiometer have any effect? It should set the 1.5 ms stop position.

Anon that wanted to replace the cooling fan for his laptop, unfortunately it's not the same model, it has a different support for one side (pic related).
Can I cut off that side support and just apply some (kapton) tape or I should just order the next model right to not fuck up?

>>1706882
Ofc I forget the pic

Why are there no affordable flip dots yet?
These things have existed for 10 years, why haven't the chinks made a clone yet? Surely they're no more complicated than a relay?

>>1706665
>the Latvian clone of the sexy bitch
reprezenta bļe

>>1706715
inductance in power feeds should be minimized, especially where very high instantaneous currents are possible
one way or the other, you'll be connecting them in series anyway. if you're stringing together a bunch of DW-01 type 1S protection boards, you're doing it wrong and you're not managing fuck-all
use a real BMS designed for the series configuration you plan to use

>>1706783
Common Core the post

>>1706882
why are you asking mechanical shit on an electronics board

>>1706994
1. complexity of mechanism ≠ complexity of assembly
2. capitalism. if you're not buying a million of them, you're not even worth talking to. however you are always free to design your own flip dot systems and have molds built and run in China for a surprisingly small price. stop buying avocado toast and provide a market for flip dots

>>1706998
nut

>>1706994

Because few people want them, even including commercial entities.

Not sure why, 'cause they're aesthetic as F (maintenance issues, maybe?), but, either way, few want them, few make them. That makes them a niche product, which invariably means you're going to be paying an appreciable premium to get your hands on one.

This is, of course, also ignoring the fact that it's thousands or tens of thousands of individual moving parts. Even at cents each and ignoring the cost of equipment, jigs, and personnel to put them together, that adds up to a fairly expensive assembly.

>>1706525
Electronics Goldmine capacitor surprise box. Shit ton of electrolytics of loads of different values. I think they have assortment bags for ceramics as well. My only complaint is the surprise box gives you kind of low voltage rating caps. 10-50V. You don't get many 100V, 200V, 400V, 600V caps which would be nice but hey, you get what you pay for. For audio you should also get polyester/polypropylene as well. You probably won't find those in a kit, at least not on Goldmine. Just go to digikey and get like 10ea of assorted values between 1nF and 1uF. Use the kit caps for prototyping then buy more from a reliable brand when you build your real projects. Get extras.

>>1707022
>inductance in power feeds should be minimized, especially where very high instantaneous currents are possible

That makes sense, but I don't expect high instantaneous currents.

>use a real BMS designed for the series configuration you plan to use

That's what I wanted to do.

>if you're stringing together a bunch of DW-01 type 1S protection boards

I didn't want to do that, don't worry.

I basically wanted to use a BMS, and connect every cell individually to it, so the BMS can "manage" them. The issue is that I have little space, so the form factor is supposed to be as if they were in series. Thus I wanted to use wires to connect them, because the cells themselves are isolated from each other.

Do you think wires with a max length of 12cm from the cell to the BMS are an issue?

>>1706549
>>1707040
Thanks for the replies. Im tempted to buy cheap ($10-15) assorted sets from amazon with 4/5 stars but theres always 1 strongly worded review warning against it. Seemingly comprable sets from my local microcenter cost $30. Ill guess ill get questionable ones for experimentation until i commit to a serious project

I need to draw out some natural color in wood, protect it from outdoor use, and UV protection.

I was told to use walnut oil, tung oil, or linseed oil. Do any of these discolor the wood? Do they deepen it? Turn it yellow or orange?

I'd like to hold onto the natural color of the wood and make sure it is protected from water and UV.

What would you recommend?

>>1707099
>I need to draw out some natural color in wood

no you dont. what you want is to make your cheap pine (or whatever pedestrian crap you got) look like some luxurious, illegally-logged, old-stock hardwood. for that you get a can of combination stain and varnish. choose a color you like then apply several coats over several hours with a foam brush. (it gets darker each time.) it'll look great for years, and if it wears out, just add another coat.

also, this is the electronics thread, so have a multi-meter handy.

>>1707112
>no you dont.
It is a rare exotic wood from Australia that I specialty ordered for a birthday gift.

I don't know how I ended up in /ohm/. I thought I was in another thread when I posted this. Muh bad.

>>1706783
>ignores rest of argument
pottery

>>1707070
the BMS expects the series string to be connected in series at the cells. it taps the voltage between each cell for monitoring/balancing. these intermediate cell taps don't draw especially high current unless balancing
>12cm
that's not terrible. it's still good design practice to make those wires as short and direct as feasible, while keeping heat sources away from the cells. maybe you can select a BMS in a form factor that can ride along with the pack

>>1706441
>but are they analog?
Uh, yeah, they can be. They aren't much nowadays, but they used to be exclusively analog electronics.
This stuff goes back to the days of analog computers.
I'm sure you know this, but op-amps can be made to create a multiply by constant, integrator, differentiator, summing, and difference modules.
This covers most of the nodes found in a data flow diagram.
If you need it to be time-discrete, just put a sample and hold. If you need a delay, use multiple sample and holds.
The only module that can't be made with an op-amp is a 4-quadrant multiplier. For that you can use a Gilbert Cell or an Operational-Transconductance Amplifier.

>>1707145
that sounds like a really silly way to implement a reverb, compared to two tin cans and a spring
>Philbrick
approved

Curious question. I was looking through some drawings I found, and there was this one that kind of confused me. There is this 4 port net switch that direct plugs into a 24v din rail psu. The switch states it.s 9-85 volts at .5 amps. However, right before this switch there is a external 1 amp fuse. Am I being weird or is that completely stupid? Wouldn't the device blow out before that fuse even had a chance to go?

>>1707236
a fault in the device that causes a dead short across the supply might destroy the wiring. the fuse is there to protect the wiring, not the device

>>1707239
Wouldn't it just be a better idea to have a .5 amp fuse instead of a 1 amp. Seems to me that putting the 1 amp fuse would destroy the device and protect the wiring, but having a .5 amp fuse would protect the device and the wiring.

>>1707248
one, inrush currents are a fact of life and might not be accounted for in the 0.5A nominal rating of the equipment. two, high input currents are likely to be an effect of a fault, not a cause. three, the fuse rating is determined under controlled conditions, and field conditions can and do vary
enjoy this fuse selection guide from Littelfuse: https://www.littelfuse.com/~/media/electronics/product_catalogs/littelfuse_fuseology_selection_guide.pdf.pdf
in particular:
>For example, one prevalent cause of nuisance opening in conventional power supplies is the failure to adequately consider the fuse’s nominal melting I2t rating. The fuse cannot be selected solely on the basis of normal operating current and ambient temperature. In this application, the fuse’s nominal melting I2t rating must also meet the inrush current requirements created by the input capacitor of the power supply’s smoothing filter.

wow, the ATtiny402 feels so much bigger than it actually is

>that intense moment when you finish connecting 50 wires wire and you finally plug your shit in and wait if you see any smoke or smell any silicon bbq

>>1707300
To be honest it's much more likely that it just doesn't turn on at all, compared to releasing smoke. Though I guess that depends on what sort of power source you're using. Kinda makes me want to have a thermal camera for troubleshooting.

>>1707302
if it doesn't turn on it's 50/50, either you forgot to connect some power or you fucked it up and the IC is already shinderu

>>1707304
if the coin lands on its side, it's a miracle, and you just connected power backwards and your reverse-protect diode caught it, and Poland will win WWII

I want to make a small pick and place machine, but how do i make sure the picked up part is centered?
do real pick and place machines have sensors for it or do they blindly relay on the part being in a correct position and rotation?

>>1707312
never mind, if you can't even google you're not resourceful enough to build one

if electricity flowing through a wire creates a magnetic field, why dont power lines attract a million small bolts and bits of metal from dirt? wouldnt such a huge amount of electricity create a huge magnetic field?

>>1707331
>ac vs dc magnetic fields
>inverse square law with distance

>>1707128
I'll try to find one, thanks. Maybe I can even reduce the cable length, depends on the form factor of the BMS mostly.

>>1707331
>>1707340
This, and because they're low frequency at (electrostatically) low voltages, the forces are very weak. If a single "winding" could produce a magnetic field strength strong enough to lift any object from multiple metres away, all motors would be brushed universal motors. But no, you have to wrap hundreds if not thousands of turns to get an appreciable magnetic field, and use proper highperm core materials even for a few cm of force propagation. Not to mention high voltages are used in order to minimise currents (hence minimising magnetic fields). Calculating the magnetic field from a pair of long wires is a pretty textbook first year physics problem using the Biot-Savart law, and calculating the electric field from a pair of long wires is even easier. Hint, the strengths measured from the ground are much less than 1T and 1MV/m respectively. But then applying that information to electromagnetic and electrostatic induction might require a bit more thought.

>>1704672
Why no one has created multimeter /scope probes that don't tangle? Is there a global conspiracy behind this???

>>1707331
>>1707340
>>1707356
http://www.emfs.info/static-fields/static-sources/hvdc/

One my multimeter probe cables broke, can I just cut the probes and solder common copper threaded cables in it's place or is there something special about them?

>>1707509
if you don't mind relatively low insulation strength and the extra stiffness of the wire and the increased possibility of failure, you do you

>>1707509

yep, they're rated for the max voltage of your meter. typical wire is rated 300V whereas meter probes have thicker insulation and are typ rated 600-1000V or better. it's also good if you can find wire that has a rubbery insulation that makes the whole wire springy: i.e. if you bend it, it springs back, so a lot less tangling.

>>1707508
>why dont power lines attract a million small bolts and bits of metal from dirt?
power lines aren't generally DC as in your link

>>1707532
Yeah I know, just sent the link to show that even in a xboxhueg DC line the field intensity is like meh. It's the same thing for the itaipu-sp line near me.

The chink freqency counter arrived today. I hooked it up the points on the board, and carefully adjusted as close as I could to 3.579545. And nothing changed.
Oddlly, when the leads are attached to the board, the picture drops out to a sickly green, that returns to the rainbow mess when I unclip the leads.
FUCK. another dead end. Now what do I do?

>>1707251
All of t fuses are slow-blow, so in the case of inrush it's not likely to actually even be a problem. All it really tells me right now is that the person who designed it, either didn't read that one of the net switches was different and decided to just give them both the same fuse.

>>1707550
the capacitance of the counter might be messing with the circuit you're adjusting. Also sure it's supposed to be continuous frequency there?

I've never fully understood V=IR.
How do parts only draw or limit a certain current. Shouldn't the current draw only depend on the voltage source and the resistance of the part

>>1707649
>what are active devices and semiconductors

>>1707550
the counter is loading it due to the big fat cap on its input. try using your BNC-to-twin-lead converter to hook up your scope probe (set to x10) to the counter

>>1707649

are you jokin' mate? what you said is right there in the formula: I=V/R. the current is proportional to the voltage, and inversely proportional to the resistance.

>>1707652
>>1707550
how about the 4.2xxxx crystal? is it in tune?

>>1704672
Whats that equation

>>1707647
I just did what the schematic said. Positive lead to TP post neg to ground. The freq kept changing minutely on its own
>>1707652
Could you diagram that, not sure I understand, put the probe to the board and the counter leads to the bnc?
>>1707655
assuming I was hooking this up right. The 4x crystal was way out of spec, unless the counter was messing with the values

>>1707669

>>1707669
shit, nm, the BNC converter's the wrong gender isn't it
>The 4x crystal was way out of spec
well there's your rainbows, fám. did you try adjusting its frequency visually, without the freq counter in place?
(the number of places that will custom cut quartz crystals for you are few and far between. I hope you can tune the color rec crystal with its adjustment cap, otherwise you may be fucked)

>>1707681
SHould be reading 4.27. Even changing the screw only changed the frequency minutely. Hope I’m not too fucked. Is 4.27 not a common NTSC crystal? Can’t seem to find one easily

>>1707690

>>1707690
it's not an NTSC crystal. it's an NTSC + VX series color subcarrier crystal
>crystal is almost 25% off nominal
and that's with all input conditions as specified? and all the voltages on the color play board check out? if so, that's bad. real bad
just for fun, try putting some medium-thin plastic sheet like electrical tape between the test point and the clip. if loading from the freq counter is pulling the crystal down, the capacitor you just made should limit the effect. otoh it might weaken the signal too much for the freq counter to see

>>1707703
Ah I see, I’ll try that out in a sec just wanted to get the shield off and take a look at the crystal.

>>1707709
Putting tape over the post just made the measurement go down. Also it may not matter but there’s a leaked capacitor right next to the crystal. Something about this unit, but almost every 47uf 16v cap I’ve come across has been leaked. Unfortunately I don’t know f I have any hand right now

>>1707714
Good news I had one 47uf left. Bad news, it made no difference. Crystal is still running at 3.2

>>1706441
DSP is more EE than CS dude

So ive been researching about 8 bit computer projects like z80s and 6062s but how hard would it be to scale those up to the power of say a dreamcast?

>>1707726
only because there's almost no math in CS

>>1707729
obviously you just use a 16-bit processor. many systems have been built around M68000 series of processors by professionals and hobbyists alike
any console is just a computer with a badass video card. not necessarily easy to generate good fast video

>>1704672
whats that weird ohme's law equation v2

>>1707749
painful reality
https://en.wikipedia.org/wiki/Maxwell's_equations

>>1707749
It's the derivation of what simplifies to ohms law from maxwell's equations, though in units of electric field as opposed to voltage (V/x = I•R/x, or electric field = current density•resistivity). The first half is all voltages (scaled as electric fields), the first from an environmental electric field, the second from an environmental magnetic field, and the third from current flowing through the wire. Then in the second half is the first term from a magnetic field interacting with current in the wire, not too sure what the second term is but I suspect the third term is about the current interacting with the charges in the wire itself. I'm a bit rusty on what those constants refer to, but I believe the eta is resistivity, and u has units of m/s.

But the important thing to note is that there are two possible definitions for Ohm's law. The traditional, common one is that resistance is a constant, equal to R = V/I, and anything that exhibits resistance that changes as a function of voltage or current violates the law and is therefore non-ohmic. This includes diodes, batteries, spark gaps, etc. But what the bottom equation describes isn't that at all, it's an equation that remains true in all possible situations, as it accounts for dynamic situations and environmental fields. The archetypical demonstration for "ohms law isn't always true" is to have your DMM leads go on one side of an electromagnet and measure one voltage, and when they're around the other side they measure a different voltage. But what this is doing is simplifying the bottom equation by excluding the EMF from magnetic fields in the calculation. This dynamic resistance would be expressed by R_dynamic = dV/dI, and such a value can be given for any "non-ohmic" device, though it may not be a terribly useful value. Transconductance may refer to this if I recall correctly.
So no they're not equivalent, but they're still both useful equations.

>>1707729
The most important thing for a console is to have powerful graphics engine (GPU).
You can get away with a pretty weak CPU as long as the GPU is capable of performing most of the heavy lifting.
If the GPU can do things like geometry transformations, texturing, and lighting in hardware, then that's a lot less work for the CPU to do.
On the other hand, doing those things in software is pretty intensive and will significantly load down the CPU.

That said, you'd probably have trouble scaling an 8-bit CPU up to something like a Dreamcast, even with a powerful GPU.
Those 8-bit CPUs tend to have oddball addressing modes or complex instruction formats, which makes them hard to pipeline, so they miss out on a lot of micro-architectural improvements.
Micro-architectural improvements are what have made modern processors so fast, since we're much closer to the limits of performance that can be squeezed out of silicon.

>>1707550
Hey I've got a lot of experience with video signals and built an NTSC encoder that can sync to an external colour burst using a crystall pull PLL a couple months ago. I think I could give you some help but your posts are spread all over several /ohm/ threads so I'm not exactly sure what you're even trying to accomplish. Could you summarize it?

>>1707797
That's pretty cool looking, do the long wires hanging out all over the place affect the performance at all? And what schematic did you use to build it?

>>1707804
I didn't copy any schematics, it's my own design. The long wires don't have a noticeable effect. All the signalling is done with 0-12v and is only converted to NTSC at the very end. A few millivolts of noise and crosstalk in the wires doesn't matter that way.

Full video of the thing:
https://www.youtube.com/watch?v=ZBEDBstWL2k

>>1707809
why didn't you just make a Scanimate

>>1707817
Scanimate uses a lot of chips that are no longer manufactured. I wanted to come up with designs that use chips that are available in the present.

I want to make a "star pointer" i.e. a moving arm that points to a star. Something like this https://www.youtube.com/watch?v=sIE0mcOGnms but for star constellations. Where should I start? I have a bit of programming experience and I took electronics in high school but I'm not sure how to tackle this. Any one have some tips?

>>1707836
this astrology library has a bunch of functions that would be useful to you for determining positions of "fixed" stars and converting/translating between coordinate systems and points of reference
https://www.astro.com/swisseph/swephinfo_e.htm

>>1707826
>available in the present
Voilà.

>>1707849
I don't know what that is, but assuming it isn't an FPAA:
>digital

>>1707797
If you could help me out that would be great. Heres the rundown
I'm getting rainbow banding when I watch a tape, and more accurately, I get these blue and red bars when I SHOULD be getting a pure NTSC signal bar display.
I replaced the 3.57mhz crystal already. I used a scope to make sure the amplitudes and levels were correct >>1707678
I finally got a frequency counter which then showed me the 4.27mhz crystal is way off
>>1707691
>>1707709

Basically I just want the color to work again so I can copy some of these tapes digitally, and then rid myself of this unit once and for all lol. Its a 1970s Quasar VX machine. There's a few on ebay that are going for over $300 broken and one going for over $700 brand new but I'm not that desperate.

>>1707866
and here's what it looks like when watching a tape

im going to be using a lithion battery i dont entirely trust to be stable, whats the best way to have some sort of over/undervolt protection? i want it to do:
v = 12<=v<=24 ? v : 0

>>1707866
>>1707867
I think that actually looks the way it's supposed to. Everything's fine here.

Trying to wire this,
note about the capacitor say :
"we recommend adding a large capacitor (1000 µF, 6.3V or higher) across the + and – terminals."
would a 2200µF ,10v be ok ?
the leds strip run on 5v, don't want to fry it

>>1707899
The capacitor is fine. You could put a 400v capacitor on there and things would be fine. The charge will always be 5v because that's what you're charging it with. A capacitor's voltage number is only telling you the max it can tolerate without exploding.

>>1707892
if i could get this to work out i think I'd get the color good again

CHROMA SIGNAL FREQUENCY DOWN-CONVERTER CIRCUIT AND CHROMA RECORDAMPLIFIER CIRCUIT1.The color signal amplitude regulated by the ACC amplifier in IC-5, is down-converted to 688KHz from 3.58 MHz. The frequency down converter consists of a balanced modulator and a low passfilter. The balance modulator, also located inside IC-5, modulates a 4.27 MHz CW signal with the 3.58MHz color signal. The 4.27 MHz signal is supplied from a crystal-controlled local oscillator. Theoutput signal from the balanced modulator, at 4.27 MHz 3.58 MHz, is supplied to the low pass filter,consisting of C77-80, and L15 and L16 from IC-5 at pin 15. Only the low frequency components, 4.27MHz minus 3.58 MHz = 688 KHz, pass through the low pass filter. The down converter chroma signalat 688 KHz is supplied to delay line DL2 which maintains the proper timing relationship between thechroma and luminance signal

>>1707915
great thanks a lot i will do it that way then, didn't knew about that capacitor voltage propriety, always good to know

>>1707916
if you want to try swapping 4.27MHz crystals, the closest I've been able to find from big distributors is https://www.mouser.com/ProductDetail/IQD/LFXTAL035831Bulk
you *might* be able to pull it down the necessary 30kHz

>>1704728
its usually made of two pieces so just break it apart
no need for desoldering

>>1705521
Acetone wrecks solder masks 100%. It does dissolve flux well though.

>>1708034
can you resend that link? when i click it it just takes me to the mouser page

>>1708265
You have select crystals and chose the frequency.
The file is called LFXTAL035831Bulk-998356.pdf

>>1708275
Thanks alot. this isnt bad, the variable resistor is only good for 0-30pf so I dont know how that translates to how much khz I can bring down but its worth a shot. At this point I have no idea what else could be causing my color issues and if this doesnt fix I might as well give up and sell off the whole thing to recoup my losses

>>1708265
but... why? a new crt tv costs $0 at the local junkyard, just buy one there

>>1708280
It is not clear how much you can pull the frequency down, it is an experiment. You may need to modify the oscillator circuit, especially the load capacitance (C119, C220) and possibly the feedback capacitors C221 and C222. I would first look at other vendors and which crystals they have on offer. Maybe there's one that comes closer to the 4.2672 MHz you need.

>>1708295
Searching for crystals is tough, the ones that are closer to 4.267 are either not available anymore or need to be ordered special from factory.
(ignore the freq counter scribbles, that was for a guy on videokarma)

>>1708309
>>1708295
Also I'm a dummy as how to individual components work in the circuit, could I rebuilt this in a sim and try out different component values?

NE555
Single Precision Timer

>NE555
>precision
ishygddt.sch

>>1708358
compared to a diffused BJT's Vbe with the technology of based Camenzind's time, the 555 is precise

>>1708295
I had a look around for our boy, that was the closest that I could find in stock in the USA
>it's only 27kHz over
oh dear, should we introduce him to crystal penning?

>>1708404
Oh shit. How would I even cut open that tiny casing? >>1708275

>>1708410
That would certainly destroy it. I would build an external oscillator and experiment with inductive pulling if the capacitive method is not enough. It envolves increasing the (dynamic, virtual) L1 in the crystal by means of a (real) external inductance wired in series with the crystal. This obviously has its drawbacks for long term stability and should be considered a last resort. I understand that this may require some circuitry I would have to draw..

Apparently I forgot how sentences work when I bought this thing.
What I wanted was a light-sensing timer that will be ON during the day, and OFF at night. Unsurprisingly this proved hard to find, and like most photocell timers this one turns ON at night and OFF during the day.

I'm trying to keep my damn lemon tree alive, and what I've found so far through google seems geared towards bigger stuff and different issues.
Is there an actual good way to reverse the operation of a photocell, or do I need to frankenstein something with relays?

>>1708446
4/10 if you know electronics, 40/10 if you don't
how about solar cells powering a relay or a dc pump?

>>1708446
Wire it white to black.

>>1708446
buy them, put the sensor of one in a light controlled by another. When it's dark the sensor will be iluminated and the tree will have no light, and during the day the sensor will think it's night and keep on.

>>1708435
neat

>>1708410
mostly only kidding. those little guys don't disassemble very nicely

>>1708454
two of them*

>>1708446
Take it apart, post circuit. It will be easy to reverse if you happen to have a couple of transistors and resistors lying about.

>>1708309
If it was mine and I could find a 12.8MHz crystal at a reasonable price, I'd give it a try.
A 12.8 'could' be operating in third overtone mode and 'may' have a fundamental frequency of 4.267 or near that.

>>1708448
Ideally I want to be able to put this back in it's housing, because it will stay outdoors. Long story short we've got an insulated room outside that the tree is in, and I was planning to stake this thing outside the room so it can see the sun, and run power back inside the room to the lights.

>>1708480
I might have some stuff, will probably enlist the help of a more electrically-inclined buddy if I get too overwhelmed

>>1708499
>188x250
Give a better photo, or maybe a part number for that relay. If it's a relay that can be reversed then you won't need any other parts, just a soldering iron and some wire.

Anyone use solder mats? I am buying a new desk around christmas time, and don't want to fuck up the top right away.

>>1708513
You mean those $5 sheets of silicone? Yeah they're not bad, but I use them more to pick up all the little beads of solder and scraps and such to easily and tip them into the bin than anything else. They're better than a sheet of disposable 5mm MDF. Considering their price, even if the silicone mats were disposable after one week you'd still likely get better value out of them than burning the shit out of your desk.

>>1708499
now flip it over and post a pic at least 1000px on each side
depending on how hard they cost-optiized the relay, you may be able to cut one of the power traces and hook up to the other one

>>1704701
Dont know if you're still around or if this helps, but heres a schematic for a late 70s hammond synth organ. Shows the IC and how each keypress works

>>1708530
and the "theory of operation" 1/3

>>1708516
Do you have a link to what you are talking about? I was thinking either the cutting grid mat you can get from walmart or something from amazon.

>>1708532

>>1708535
3/3

>>1708504
>>1708523
Oops, anyways the part number is GJ-1A-12L, and I did find a wiring diagram for what I assume is a similar one, which shows it as a single-pole, normally open relay.

>>1708537
irrelevant flex but ok

>>1708533
https://www.aliexpress.com/item/32813322677.html
Those common green plasticky cutting mats likely aren't heat-resistant, not sure about the black rubber ones though.

>>1708571
Since it's a single pole (the 1 in GJ-1A) you'll need to do some more complicated rewiring, as opposed to just swapping NC and NO. In other words, reverse engineer the entire circuit diagram. You could also just post a (HD) picture of the other side of the PCB and hope that it's welcoming enough for someone here to do the work. Which it probably is, knowing the power of autism.
Just pop both sides into photo editing software, flip one, distort them both to be rectangular, then superimpose them and draw traces atop them.

Best case scenario, the LDR will be used as one side of a voltage divider as opposed to a variable current limiter, so just swapping the LDR and that resistor will result in the desired flip. I think the same applies to a photodiode or phototransistor also.

>>1708577
Irrelevant how?

>Have my dad's truck for the week
>Notice overhead temp display / compass isn't working
>Crack it open and see crusty broken solder joint on a resistor
>Resolder the joint
>Works
Damn that feels good

>>1708615
based frogposter

>>1708614
I though he needs a control voltage and gate signal to play an existing or planned analog synth, not a whole polyphonic tone generator section integrated into the keyboard
his problem's been solved anyway, aside from his whining about having no chops

>>1708595
actually, the problem is the A, as in Form A (single-throw) contacts. Form C is double-throw
if I were designing such a device I'd put the threshold at one Vbe drop rather than bother with a comparator, so he would need to change the resistor too. comparators cost money. I'd probably also be eating piss eggs and dog meat

>>1708655
>actually, the problem is the A
Oh yeah, it's the throw that matters, not the pole. I need to find some sort of mnemonic for that.
Cheap 4-pin (SOT23-4?) comparators with their threshold set at (Vcc - Vee)/2 would be pretty nice to just throw in every circuit, but you're probably right that they don't use a comparator.
>one Vbe drop
I think it's more proper to rely on a FET's threshold voltage so the transistor isn't constantly wasting current through the relay. Otherwise there's a bit of a limbo period where the transistor is half-on and the pullup resistor would constantly be draining current through the base. Just using an NPN with the LDR from Vcc to the base and no other resistor would minimise part count, and also make it a pain to reverse the operation of.

>>1708656
pole/throw might be a semi-deprecated terminology anyway. at least the industrial world seems to have settled on the contact form taxonomy
>FET's threshold voltage
those aren't all that crisp either. good point, I didn't mention the second power switching stage I had in mind. maybe a little positive feedback Schmitt trigger-style
>cheap 4-pin comparators
thanks for reminding me, Pic related

>>1708661
>maybe a little positive feedback Schmitt trigger-style
I was wondering about that, but I thought doing so would require the main switching transistor to have en emitter resistor. Not a problem if you have two transistors between the LDR and the relay.

That's an interesting use of a voltage reference diode there, but I can't help but wonder how stable it is as that "comparator" in there is usually meant to operate in the linear region. Still, more than good enough for this low-speed application. With an absolute maximum of 150mA cathode current, you could certainly use it to turn on dim LEDs, or maybe even some low-coil-current relays. It is ≤37V though, which makes me wonder what sort of power supply is going on within that light switcher circuit. That big film cap combined with a decently-sized electrolytic makes me think it's a capacitive dropper of some kind, which would work fine because the relay coil is isolated from the contacts. Not too sure what the other electrolytic is doing though, I can only assume it's part of some low-pass filter.

I should get me some of those reference diodes, better than slapping a voltage divider and op-amp buffer on every 5V op-amp project I do. They're also really fucking cheap.

>>1708656
>>1708661
>>1708670
Sorry to barge in like I am doing right now, but can you guys maybe help me repair a DENON AVR-2106 that has presumeably had its speaker outputs shorted? I can't post pictures at the moment since mountiny my phone isn't working on GNU/failure (but I like it nonetheless).

>>1708530
>>1708532
>>1708535
>>1708537
Thanks, that looks great

>>1708655
>aside from his whining about having no chops
Never mind, fuck you.
What makes you say that?

Massive idiot here, wtf are these dotted circles

>>1708931
shielded cables

>>1708865
wasn't the main concern that the keyboard would send a CV not corresponding precisely to a key if the musician hit two keys at once?
I mean, if you want it to play like a digital device, stop fucking around with analog and make a scanned digital keyboard with CV DAC and gate output, as so many who came before you did. you're not going to solve problems with 1970s technology that the ancients who designed the things didn't solve with 1970s technology. capitalism is cancer

Anyone own a Heathkit IG-18 signal generator? I just picked one up recently and want some input on what mods I can do to improve performance. I know that there are several, but I do not know how far I should take it. The modifications range from stuff like this somewhat "simple" stuff like this board to isolate the meter from the rest of the circuit (https://shop.heathkit.com/shop/product/thd-improvement-kit-for-ig-18-series-audio-generator-test-equipment-meter-buffer-board-only-iga-18-2-4)) and then there's stuff like this here (http://tronola.com/html/ig-18_mods.html)) which is pretty much a complete circuit swap.

>>1708947
thank you so much
I just looked it up and somebody suggested I could use metal foil for RF shielding
So, would I connect pin 2 to the metal foil, wrap the UART and Vcc line in foil and connect the ground to another part of the foil?

again, please forgive me. I suffer from massive idiot syndrome.

Hello friends

I have an interesting problem I'd like some input on:

I'm working on an automated drone team with a bunch of undergrads who may as well be as dumb as bricks.

The drone is very large (13 inch props, hexacopter) and thus is very dangerous, its blades could easily take someones head off at idle speed. We've had a lot of problems with people writing programs for the drone with no way to shut it down in an emergency.

I've been tasked to set up a wireless failsafe/dead man system that can completely shut off power to the drone in an emergency. I was thinking of having a handheld remote with a switch on it that links to a basic receiver/power mosfet that can cut power immediately.

Originally I was gonna use an off-the-shelf RC radio/receiver, but I found that they have very spotty performance at our max operational range (1/2 mile, LOS). This drone has about ~10k of equipment on it, so the failsafe being triggered accidentally is a big no no.

What more-reliable options are there out there for a very simple RX/TX wireless link? A friend recommended a basic 800mhz superhet receiver/transmitter combo, but I can't find any parts with documentation on operational range,

>>1708978
low-impedance current-mode links tend to be robust against aggression, but can be aggressive. for a short wire in a clean electrical environment, shielding here is optional, and more intended to keep the MIDI off the audio than keep electrical infetterence out. try without, add shielding if needed

>>1708715
Shorting the output would probably bake the output transistor(s), so you're likely going to need to replace those. Some more components up the line could also be damaged, both passive and active. Take it apart and see if any components look damaged. Worst case scenario, you also blew up its PSU.

>>1708978
Twisting the wire pairs could help with noise also, no real reason not to do so.

>>1708996
>infetterence
i like this meme

>>1709012
>>1708996
thank you guys so much!!

I'm looking to adapt https://www.instructables.com/id/Lo-fi-Arduino-Guitar-Pedal/ to work with a modular synthesizer

I sorta understand his schematic, but I wanna know how to get it working with -5V to +5V instead of -1V to +1V

>>1709030
Feed your input signal through a DC-blocking capacitor, and tie it to both +5V and -5V with identical resistors. That will get your signal moving on either side of 0V, provided your high-pass corner frequency is sufficiently low. Equivalently, you could have a single resistor to 0V, though this will mean more current being sunk/sourced into your (virtual) ground, which isn't necessarily a good thing. Depends on whether your ground is more stable/ripple-free than your rails at those currents. But if you want a signal that actually goes near the full ±5V capabilities of your rails, you'll likely need to amplify it to increase the signal amplitude. A common aux signal has an amplitude of something in the ballpark of 1V, so you'd likely want to use a non-inverting amplifier to bump it up. Bonus points for having its gain be adjustable in case you're dealing with signals of differing amplitudes. An LM6132 is a relatively common rail-to-rail op-amp that might serve you well, if you want to get real close to those rails, but common op-amps (LM358) are still good to within 1V of each rail.

>>1709030
>>1709042
Oh and that circuit you posted doesn't look like -1V to +1V to me, but rather 0V to +1V.

do any of you guys know what IC/type of IC is used in those record-your-own audio greeting cards?
I tried googling the numbers on this one but I'm getting nada

>>1709045
The actual ICs are almost always Chinese-market specials, hence why they quite often come in chip-on-board format.
If you're looking to DIY something, look at the ISD1820 or APR9600.

>>1709042
I appreciate you so much.

I typed it out wrong in my post and meant for the input to be -5V to +5V with the output being between 0V and AREF (which I think is 5V, but can also be adjusted) on an arduino.

>>1709049
This is a case where using a sim for the analog parts of the circuit would help. Hope you learn something!

>>1709050
Thank you!
Do you know any good sims?

>>1709047
thanks boss, I'm trying to make a shitty tiny portable drum sampler

>>1708979
you don't need rx/tx for a deadman switch. broadcast a tone, and when it stops recieving the tone it crowbars the battery pack, blowing the fuse.
an appropriate frequency and the operational range can only be determined in field trials, because drones are electrically noisy and we don't know what else might be on the air. ideally for safety you want a very loud transmitter in hand and a near-deaf reciever on the drone.

>>1709052
Rad. You can get the ISD1820 chips for 50 cents or less from Alibaba. You could stick a bunch of them together.

>>1709051
see the OP
the falstad link is quick, dirty, and usually close enough

>>1709051
I use LTSpice, it's a bit finicky to get used to but it seems to be pretty powerful.

>>1709012
Thanks for the answer on that AVR, I am unsure if I can find out what things are broken and what is fine, also: how long do I have to wait for those rather huge caps for them to not be a death trap after switching off the power?

How do I zener zap a discrete zener?
>>1709063
>all that money I don't have being blown to bits
It pains me
>that jet robit getting slapped
top kek

>>1704672
Slightly off topic but does anyone know where I can find the answers for the problems in pic related?
I'm self teaching but it's a university textbook so the publisher only releases the answers to "verified instructors" to stop retards cheating.

>>1709272
No idea, but there are better books to study by. The guy who made the 555 made a wonderfull one. My self learning electronics library is gigantic but
>the art of electronics
>cool app notes from linear tech
>designing analog chips, hans camenzind
are good starts.
I'm a EE graduate and studying with Sedra's microelectroncis and other similar books (fuck huge, full of exercises that are more of the same) just made me more confused.

>>1709275
Thanks for the advice anon. I actually looked at quite a few books in my uni library (I'm a CS student but there's nothing stopping me taking out books for other courses) and this looked like the best one to me, I also checked reading lists and it's the main book used to teach EE at my uni. I actually have a copy of AoE checked out next to me at home now but from my quick look through it it seems to really just be a reference book, introductory topics are covered too briefly and it starts getting into really complex stuff early on. This book on the other hand steps you slowly though all of the fundamentals covering them fully.

>>1708325
trying to do this in a sim sucks because most of the parts dont exist anymore lol, i have to figure out how to custom edit the crystal to make it 4.27

>>1709338
one more discovery i found this morning is that if I put the frequency counter at B1-2, I get ~688khz.
According to chroma standard, 688 is only derived from the subtraction of the two crystals:
>Only the low frequency components, 4.27MHz minus 3.58 MHz = 688 KHz, pass through the low pass filter. The down converter chroma signalat 688 KHz is supplied to delay line DL2 which maintains the proper timing relationship between thechroma and luminance signals
meaning the crystal would have to be at 4.27 for this to happen...
I have no idea whats going on now, maybe i need to look at this >>1708435
>>1708455 lol

>>1709343
do you have a scope?

>>1709358
yeah, where do you want me to scope it at?

>>1709359
T204 and nearby GND to confirm the reading of your frequency counter.

>>1709364
Forgot to mention that you should use a 10:1 probe to keep the scope capacitance low.

>>1709364
>>1709367

here's the scope at .2us horiz 20mv div. with 10x probe.

whats interesting is that hooking the scope to TP204 does not overload the color circuit while hooking the frequency counter to TP204 overloads the color until i unclip it.

>>1709369
fuck sorry, that one is .5us
THIS one is .2us
each period would be .24uS

>>1709369
I would display one or two cycles and read the cycle time. The difference between 3 MHz and 4 MHz will be obvious: 0.23 µs per cycle means 4.27 MHz.

>>1709379
This looks like the counter was losing cycles and the crystal seems to be ok.

>>1709384
well fuck, that means I still havent figured out my issue then. hell if I knew you could get a rough frequency reading from a scope I wouldnt have bothered with the chink counter from ebay lol.
well back to square one

>>1709387
>frequency counter to TP204 overloads
If your scope has a sync output you could connect the counter to that. If not, the counter has a low Z input and needs a buffer/amp for such cases.
Moral of the story: a scope never lies, always use it first.

>>1709391
solid advice. well if the output is indeed 688khz then its time to follow it along the line. better check out the DV board for any faulty readings..whew

>>1704672
Hey guys I'm an electronicE student looking for a good book on embedded systems. Anyone know the *best* one? I value the concise and intuitive books without training wheels (but still thorough). That's kind of oddly specific but anyone got one? Thanks in advance

>>1709240
Short them with some insulated pliers or scissors or something if you're worried. Chances are there's a high-value resistor in parallel with the caps, so if you can read that value you can calculate the time constant and wait for at least 5 of those.

>>1709253
>How do I zener zap a discrete zener?
Get/make yourself some sort of time-controlled high-current pulse supply, that can send a few hundred mA (possibly set just by a resistor, or a potentiometer/DAC on a transistor amplified op-amp feedback network) for a variety of time durations (perhaps 10µs to 1s, easily done via arduino if you want to go that way). A scope would help in quantifying your results, and I'd take care to measure the V<Vz reverse current after each zap to see if you've done any permanent damage even before establishing an ohmic link.

>>1709486
I too agree that there are many people on this board who need to kill themselves

>>1709253
y tho, get a one-time fuse and put it on the board. this is literally what some printer manufacturers do to detect virgin toner cartridges and establish dominance

>>1709510
>fuse
Don't you mean antifuse? A MOV would work fine if he wan't something resettable, and a simple silicon diode (or even LED) would probably work just as well for permanent action, though I guess their reverse voltage isn't as set in stone. Not like it matters in the case of series christmas lights anyhow.

>he doesn't own 1000V insulated tools

>>1709512
it wasn't clear the zener inquiry was related to the drone safety leash
>he uses 1000V insulated tools on 26kV capacitors
dis gon b gud

>>1709548
>26kV
where did it say that?

>>1709551
lol nm I got my posts mixed up, also I make my martinis by replacing gin with jizz

>>1708962
>you're not going to solve problems with 1970s technology that the ancients who designed the things didn't solve with 1970s technology.
It's not like it's impossible to do, you just need to put an ideal diode between each key and the bus.
It's doable for a one or two octave keyboard, but it can get pretty expensive for a full keyboard.

>>1709599
yes, that's a possible idea, and also disproprtionate to the improvement achieved. if anon want a perfect performance, why in the hell is he using an analog synth in the first place and not just going out and buying an Access Virus or someshit? the whole attraction of these old machines is their elegance (achievement * versatility / complexity), and then comes some fuck-trophy wanting training wheels on his violin. it is our duty to tell the student why things are a bad idea when they try to push them too hard

>>1709604
>t is our duty to tell the student why things are a bad idea when they try to push them too hard
Nah, I prefer the "let them learn from their mistakes" route. It drives home lessons much more thoroughly. All you need to do is ensure they don't blow so much time or money on it that they get eternally discouraged from trying new things, and ensure they learned the correct lessons and direct them in a better direction for the next attempt.
t. eternal failure who is constantly designing flawed circuits and never builds anything

>>1709604
>Wah! Somebody is trying to improve upon old technology!
>Any improvements to alleviate old limitations are training wheels
This is you.

Obviously not every modification is necessarily an improvement, but it's not like you can't improve upon things.
Old analog synths have that limitations because electronic components were much more expensive in their day.
Nowadays op-amps are dirt cheap and it would be feasible to add a super diode per key. It drives up the cost a little bit, but you could do it if you so desired.
It's not like adding such an improvement creates any new limitations, it just gets rid of a nuisance present in the old designs.

>>1709624
>character is a deficiency
to a conformist high school kid who thinks auto-tune is musical, maybe
personally, I would consider it an advantage to take an approximately half-semitone step in either direction without causing a retrigger, by just pressing the key on either side of the desired note. beats reaching for the mod wheel. also beats ideal diode shit which, by design, only errs in one direction
>a super diode per key
my point is, it's a solution whose autism outweighs its utility, which imho is negative, unless you really want the soldering practice. if "ew analog" is too grotty you might as well decode the keyboard to digital with 74x148s and use an R/2R DAC for output. something about favoring simplicity and directness to larp

>>1709630
>74x148
Personally for my keyboard I bought a dozen 74HC165s, this way I can have multiple keypresses at once. With no debouncing, because I'm not triggering on the button-presses and can probably rely on the latching delay to get rid of that for me, so long as the bounce period is significantly shorter than the inverse of my sampling frequency. Then I'll feed that into some sort of badusb midi MCU setup I guess, but it would be potentially viable to have some logic and ~4 hotswapping analog oscillators. Which actually sounds kinda fun, but having 4 resistor ladders, each with as many inputs as there are keys on the keyboard could get bad quick, so I'd likely try turn it into a digital logic PWM setup somehow instead.

>>1709653
oh yeah, for the funky silicone button thing right?
DAC0808 in DIP16 is an active part number and not outlandishly expensive. I think ±0.1% linearity might even be suitable for ensemble performance. the analog polysynths of the time used as few as 10-bit DACs iirc, but the self-tuning Prophet-5 had a 14-bit ADC. in each case a crapload of op amps, low-leakage caps, and 4016 CMOS switches served as voltage holders for each CV in the things
polyphonic synthesis doesn't play well with 100% analog circuitry. for one thing, chords would attack like mush as single notes kept getting moved to another oscillator. a processor to handle voice allocation is essential. many Motorola 680x chips were sold into these machines

>>1704672
Should I bypass the regulator on my shitty flash cart/bootleg "repro" so it runs at 5v?

explanation: New carts for retro consoles, mainly chinkshit but also homebrew/"repro" publishers etc more often than not use 3.3v parts connected to the 5v address/data bus of your console.
Without level shifting. Maybe a resistor network.
But in the case of bootlegs, ABSO-FUCKIN-LUTELY NOTHING between the address/data bus and the cart.
The chips are powered either via a 3.3v regulator or a "tiny diode" or even TWO "tiny diodes".

Everdrive flashcarts either have proper voltage translation, or fuckin' resistors. Depends.

The problem is the 5V from the address bus goes through the diodes to VCC, which I believe basically powers the cartridge from the system's address bus.

There is proof that these bootlegs have damaged consoles.
https://twitter.com/Fisher_Moraes/status/1103373431138066432
This thread has some very immature "rebuttals" from Piko, a "repro" publisher who sells 3.3v carts.
https://twitter.com/Voultar/status/1083579348618301442

If I bypass the 3.3v regulator in the cartridge, will it do harm to the console at all over time? Or just the cartridge and/or SD card?

how the fuck do you measure bood pressure with a solenoid?

>>1709712
not easily

>>1709712
just pucker up your lips and blow

>>1709712
look up 'blood pressure solenoid valve'

>>1708979
>10k of equipment on it, so the failsafe being triggered accidentally is a big no no.
just wire it so when it shuts down i deploys a parachute
it won't get damaged and look cool as fuck

>>1709800
>>1708979
Nah, it's too risky a wireless signal can fail any time. A much simpler solution would be to add a liquid detecting sensor and if it detects blood it shuts down the propellers

NEW THREAD

>>1709841
>>1709841
>>1709841