Fan speed control by OP of amp.
The two big monoblocks I built get very hot after a while, I have a fan drawing air up through the PSU, this then goes into the amp chassis to cool things there, then through six holes round each OP valve. To reduce fan noise I put a 100r to slow the fan down, at low volume it can't be heard, but to cool the amp it needs to be on full whack.
So I thought of taking the OP after the OPT, into a buffer, a 10M and Opamp buffer, into a diode to rectify, into a "comparator", OP from this to a tranny to turn on a relay which will short out the dropping R on the fan, see att.
Anything I've missed? Andy.
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