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/diy/ - Do It Yourself


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1770546 No.1770546 [Reply] [Original]

How do you measure core loss in a toroid ? I need to trace those graph like you find in core datasheet where the losses in W/cm3 are function of B.

Is there a good alternative to the Iwatsu SY-8218?

>> No.1772552

>>1770546
Watt meter, ammeter, voltmeter, a variable AC supply (Variac) and a bunch of math.

>> No.1772996

>>1772552
I'm talking in the range 10-100kHz 20amp. No chance with a variac. Could use a audio amp, but looking for a cheaper solution.

>> No.1772998

>>1772996
>but looking for a cheaper solution.
Not gonna happen

>> No.1773006

>>1772996

What sort of accuracy, National Bureau of Standards, or hobby level? I'd go back to the basic equations and use opamps and a scope.

>> No.1773100

>>1773006
10% would be good enough. The problem is not the measure itself, it's how to excitate the code correctly and reaching high B field with low mu material (like 19 or 26)

>> No.1773130

>>1773100
VCF --> VCCS

Feed a slow ramp voltage into your VCF. The output of the VCCS should have multiple transistors in parallel with a large heatsink. You also need a DC supply capable of supplying 20A as well obviously.

Use B-field probes for measurement.

>> No.1773743
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1773743

>>1772996
>Could use a audio amp, but looking for a cheaper solution.
I think the cheapest solution is to build an amp that can deliver 20 plus amps, why not just do that? theres a lot of full schematics out there, some of them can be relatively simple you just have to cascade output stages to get 20 plus amps

>> No.1774020

>>1773743
Would that work up to 100kHz with almost pure inductive load?

>> No.1774030

>>1774020

If you know the impedance at a frequency then you know what voltage is needed to drive the current.