Mountaindude has been spending some time lately working on 12V fan controllers and thought he’d share his experiences so far.
“While trying out various computer and network gear, I quite often find the fans too loud. They are of course there for a good reason, but experience tells that the device usually works just fine with less cooling.
Going through a 7805 data sheet for other reasons, I suddenly realized that a 7805 set up in variable voltage configuration should work great as a fan controller. These 12V fans usually run just fine down to 5-6 volts, but at lower RPMs, and thus quieter. Just what was needed!”
You can find project details and schematic at Ptarmigan Labs.
Via the contact form.
for nice, quiet fans, I hook them up to 5VDC via a USB connector…
ohh come on it’s not that dedicated chips are very expensive.. plus as someone has already posted it might be be a better option to reduce voltage. I don’t like the idea of wasting power thorugh 7805
kerimil: You mean like a fancy 555/556 based PWM fan-speed controller?
Of course, as it says at Ptarmigan Labs, Mountaindude built it with junk-box parts on-hand, while a you may not have a PWM controller or a small microcontroller (e.g. ATtiny or PIC10) and (if necessary) pass transistor just lying around.
It is good for a cheap and quick hack, but a PWM controller based on a dual timer (556) and IRF5x0 MOSFET would be preferable at least in general, with the benefit of reduced thermal dissipation and still low cost.
It is October 7th, and I now just stopped laughing at the fact that you called a 555 fancy.