Thermistor Sensor, Arduino driven Mosfet IRFZ44 used as a DC Supply?

[toxsick]

Hi All,

I have been using my arduino for making projects for a while now, and love it, I have created a cool lighting system for a computer,
the fan speed control I have is kind of silly in terms of me removing a TRIMPOT from a DC-DC Converter.
Basically I have used a bunch of resistors to find the absolute quietest noise from the fans and made that speed 1
speed 2, 3, 4, 5 have extra resistors to push the voltage up. so when 1 sensor gets over XX degrees it adds 1x Speed
the ardunio outputs to a relay board where the resistors join the DC-DC Converter and the 4 relays when all on make fans run fast.

It's a little stupid and basic and creating a way to allow detection of CPU Thermal and push fan speed according to that. but I need CPU, GPU, PSU, HDD temp to be XX degrees for max Speed!!!! it's a little troublesome.. so the mosfet driven fan would be great

anyways I am thinking I would like to create some kind of precision fan control for the attached sensors. It would be great logging in to the arduino and altering the fan curve as I go! haha

Running mosfets without capacitors on the output, is that bad?? for the lights it seems to be ok, I am just not sure about the PC Fans.. can they run off pulsed 12v?

I would imagine the output would be dirty being pulsed..

for the fans which are Delta 120mm blowers, 12v 2A max 3 of them, are used to pressurize the box and blow air into hard to reach areas.
So if i want to use caps would I just want to add a 16v 1000uf Cap or similar to smoothen supply? or totally unnecessary?

or would there be an even better way to accomplish this?

regards
shaun

 

[schmitt trigger]

If the blower motors are normal, permanent magnet brushed ones, you can drive them directly with PWM. Absolutely no problem.

You will have to choose the frequency to be high enough such that the motors dont produce an audible "whine"'.

 

[toxsick]

thats good to know, yes I know the sound..

If a Dc-DC converter is anything similar I remember tuning in with the resistors finding the lowest speed and at very low speeds there is a whine, as to why I speed up to prevent noise and bearing wear

cheers