On demand 12V fan control

Mar 28, 2012 3 Replies

Under therrmistor control. If at power up the DC voltage is too low to start the fan can you always rely on the fan starting at some point with a slowly increasing voltage or does it depend on the make/design of fan ?


On Wed, 28 Mar 2012 15:07:03 +0100, "N_Cook" put finger to keyboard and composed:

FWIW, here is an article that shows the innards of a typical thermistor controlled CPU fan:

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- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Some Studiomaster Powered Mixers used to adopt this method - the fan would sit there shaking like a shiteting dog, often making various squeeks, before finally getting going. It was driven by a TIP32.

I have no idea whether they specifically chose a fan that would always start though.

Gareth.

"Gareth Magennis"

** A great many power amplifiers have the same kind of circuit.

BLDC fans start reliably when the applied DC voltage is about 33% of ated - no matter how slowly the voltage rises.

IOW there is no need for a kick start.

... Phil

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