how many of IRFP240 will match in one batch of 100 units? - Page 2 - diyAudio
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Old 18th February 2013, 01:33 AM   #11
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i mean not for the n and p type match but for each channel n or p...
the group size can be 6 so how many of such groups can be achieved is the question... let me try....

I think just for one pair of output since n and p need not be matched i think we can just use one n and one p for small power amp..
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Old 18th February 2013, 06:07 AM   #12
h_a is offline h_a  Europe
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It largely depends on whether you can get your hands on fets that come from the same batch (same lot-code). For these matching is much more effective and has the added bonus that the other fet-properties are very similar as well.
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Old 18th February 2013, 03:55 PM   #13
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Quote:
Originally Posted by nigelwright7557 View Post
I have never found the need to match 240/9240's
The source resistor should help balance things.
Not in a Pass MOSFET amp. Emitter resistors yes,
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Old 18th February 2013, 04:20 PM   #14
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And what voltage and current do you guys match them to?
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Old 18th February 2013, 04:56 PM   #15
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Quote:
Originally Posted by KatieandDad View Post
Not in a Pass MOSFET amp. Emitter resistors yes,
In a pass MOSFET amp, what emitter Rs are you talking about? The concensous here, I agree with regarding Source Resistors. You need to match your pairs, quads etc., of the same sex, attached to one rail. It is extremely difficult and expensive to match the other sex with the other rail. IE; N-N-N match's and P-P-P match's is all that is ussually attempted. No N-P match's are easy. It is possible to match P-N but you need alot of outlying Vgs etc. parts to find matches. It is not really designed or intended to be a complementary device. You are lucky if you find matches.
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Old 18th February 2013, 05:19 PM   #16
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Match as closely to your intended use as you can. For the Aleph X, I did 22V at .75A for 45 seconds. IIRC, the rationale for the current and time is so that the FET doesn't heat up too much since it's not sinked during matching. If you were really hard core, you would sink it sufficiently and wait for steady state.
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