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GB for F6 Convertible Clone boards

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zman01

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Joined 2011
I was planning to do "standard build" using +/-24V power rails. My JFETs have IDSS of 7.25mA. If I understand correctly, your build blog advises to use 2x blue LEDs for biasing IRFP240. With the 16N25C the bias will be needed to be reduced quite a bit?
 
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Tea-Bag

Tea-Bag

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Joined 2006
Paid Member
zman01 said:
I was planning to do "standard build" using +/-24V power rails. My JFETs have IDSS of 7.25mA. If I understand correctly, your build blog advises to use 2x blue LEDs for biasing IRFP240. With the 16N25C the bias will be needed to be reduced quite a bit?
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The LEDs or using Z1 is meant to get enough gate voltage to conduct the MOSFETs. The two LEDS give more voltage than the original 1 blue one used when SemiSouth's were in the circuit.

P2 can set the Bias of the circuit. Here we would want to keep the smaller FETs from exceeding 65c on the die, and no more than 60c on the direct heatsink next to it, and 55c for overall heatsink temp. Generally this will result in lower output into class A, but possibly worth a good listen. Small tweaks seem to be easily heard in the F6, less so for M2 IMO.
 
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