AVR microcontroller based PWM fan controllers

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Zak Kemble posted his AVR based PWM fan controller build:

So this is a bit of a continuation on my 555 timer based PWM controllers, but now using microcontrollers and MOSFETs instead of 555 ICs and transistors. I made 2 versions, one with switches for speeding up and down and the other with a potentiometer like the previous controllers. I used ATtiny25 controllers running at 31.25KHz (8MHz internal RC / 256 prescaler) with a 3.3V supply, the MOSFETs I used are STP36NF06L with 0.045Rds and 2.5Vgs max, perfect for 3.3V, the MOSFETs only generate ~180mW of heat at 2A ((0.045Rds * (2A * 2)) = 0.18W) so no heatsink needed, you can barely feel them getting warm.

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1 Comment

  1. Neat. Wish there a PWM to voltage controlled fan converter. Some motherboards only have PWM support now and most fans are still voltage controlled, so there’s no way to get feedback of fan speed to the motherboard when you have voltage controlled fans :-P

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