From: Chris Carlen
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Subject: Re: My flyback experiment is on the web
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Date: Tue, 15 Oct 2002 03:21:52 GMT
NNTP-Posting-Date: Mon, 14 Oct 2002 20:21:52 PDT
Frank Bemelman wrote:
> Just a question to thicken the plot: is your 1 ohm current sense resistor
> wirewound, and does it have an inductance too ?
I honestly don't know, but am inclined to think it isn't. It's a little
precision resistor, strange looking black cigar shaped thing, about 1W 1%.
But it has a very small diameter, so it can't have much inductance. I
suppose that could slow the FET turn-on by allowing the source to rise
up on the rising edge of the gate pulse.
But it seems to me there'd be some tell-tale signs of this, like a
segment of exponential rise in the current ramp before flattening out to
a linear ramp. But this isn't happening.
OTOH the little ring bursts coinciding with the gate drive edges could
be coming from this resistor, if it is a wirewound.
I am planning to get some for certain non-inductive current measuring
resistors in my next ordering cycle.
What I'd really love to have is a good high frequency and high voltage
differential voltage probe, so I could stick a resistor in the drain
instead of the source. Maybe I should learn how to use a current tranny?
Christopher R. Carlen
Suse 7.3 Linux 2.4.10