we need to drop at max 28v (40v - 12v) each rail. a total dissipation of 28v*0.29a=10w.
the typical zener we have (in47xx) cannot handle 290ma. those zeners are supposed to be used at <75ma.
I would say build a simple regulated PS with a 13v zener, a medium power transistor and a few resistors / caps.
the typical zener we have (in47xx) cannot handle 290ma. those zeners are supposed to be used at <75ma.
I would say build a simple regulated PS with a 13v zener, a medium power transistor and a few resistors / caps.
so, the idea here is to make heat to reduce heat?
for about a buck (an LM3524, an inductor, one transistor two resistors and two caps) you can make a relatively quiet buck converter. and with the LM3524 you can use a little creativity to drive the error amplifier with a heat sensor to ramp the fan speed with heat.
for about a buck (an LM3524, an inductor, one transistor two resistors and two caps) you can make a relatively quiet buck converter. and with the LM3524 you can use a little creativity to drive the error amplifier with a heat sensor to ramp the fan speed with heat.
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