I need to make a fan controller.

[shadow]

Re: I need to make a fan controller.

There are a huge number of different ways you can create your own fan controller. I will list the ways I can remember off the top of my head.

1) Use a potentiometer as a simple variable resistor. The trouble with this is that you want to control multiple fans with a single control source. Therefore the potentiometer would have to be pretty beefy to withstand 4W of power. They probably exist but cost a fair bit.

2) Use diodes in series. Each diode you place in series with the fan will drop around 1.2-1.7V. I have seen people online hook up diodes through a 'selection' (forgot the proper name) rotary switch. For every click on the rotary switch, another diode goes in series with the fan, therefore reducing the voltage at the fan. This may suffer from the same fate as the potentiometer. The diodes you use would have to be reasonably beefy. However they do exist and won't cost much.

3) I have seen people online build their own analog PWM circuit. You would have a low powered signal to adjust the duty cycle of the PWM circuit. The switching transistors you use for the circuit will need to be able to withstand 4W of power (pretty easy to come by).

4) I have seen people online build their own linear controller circuit. I can not remember the details of this approach. However it is an analog circuit where a low powered signal (which can be controlled by a knob) can adjust the output voltage. Disadvantage is heat. To reduce the voltage in a linear circuit, you need to 'absorb' the extra energy which normally means dissipating it as heat.

5) My favourite solution is to use a simple microcontroller based solution. Nearly all microcontrollers have a number of PWM outputs and a variety of different inputs (digital and analog). One would normally program a microcontroller using C. Essentially you would connect your inputs to the microcontroller. Lets just say something liked a switch or a potentiometer and you connect your fans to the output. The output circuit (PWM signal) will need a transistor based switching circuit because the output signal from a microcontroller only carries a tiny amount of current. You need to amplify the signal using a transistor circuit so that it can handle the power output you wish to use. Transistors that can handle a few amps are cheap and easy to come by. This is my favourite idea because I love programming, it is simple and it gives you ultimate flexibility. For example, if in the future you may want to have a temperature controlled fan controller. Just hook up thermistors, thermocouples, temperature measuring IC's or any other kind of temperature dependant sensor to the microcontroller. Reprogram the microcontroller and you have exactly what you want. Add to this, Arduino and Arduino clones are pretty cheap now, it is reasonably cost effective solution as well (most likely will still cost more than the other solutions I mentioned thou).

[Mad_Professor]

Re: I need to make a fan controller.

I don't know if I want thermal control. Call me old fashion but I like manual control. as c_hegge said the thermistor will heat up.

Anyways I'm kicking around the net looking for designs and ideas..

I've found one over at overclocker.com

http://www.overclockers.com/forums/s...d.php?t=677283

also

http://www.overclockers.com/forums/s...d.php?t=646148




1 LT1083CP or LM1084IT-ADJ
2 Capacitor, electrolytic 330uf 25V
1 Capacitor, electrolytic 1000uf 16V
1 resistor 10 ohms
1 resistor 3600 ohms
1 resistor 1200 ohms
1 10K POT
2 1N4002 diode

[c_hegge]

Re: I need to make a fan controller.

^
That does have on major problem - drawing any more than 4W through a thermistor will cause it to heat up, so it will just run the fan at almost full speed.

[ratdude747]

Re: I need to make a fan controller.

So here's the deal, I put some new fans in my server to replaced acouple of near dead/dead fans. The new fans are LOUD! but they push alot of air.

Anyways I have 4 of these babies pushing air pass my raid array to keep those drives ice cold.

The fan itself takes 12v 0.34 amps or 4.08 watts.

I can't find anything that meets my needs.

I'm looking for a master control, not individual control. Something like APEVIA FC-01 Multi Fan Speed Controller but can handle more amperage, 1.2a is low.

I was thinking about building my own, but I'm not an electronics engineer so I'm not sure where to begin.

Any ideas?

what would I need?

I am not an eletrical engineer... yet (3 more years of school), but I have an idea:

you could maybe use some sort of a thermistor circuit? thermistors decrease resistance as temperature goes up... so put a thermistor and a pot in series with the fans and with careful part choices and tuning of the pot you have a temp control circuit. for optimal control, put the thermistor at the exhaust of the air system.

[Mad_Professor]

So here's the deal, I put some new fans in my server to replaced acouple of near dead/dead fans. The new fans are LOUD! but they push alot of air.

Anyways I have 4 of these babies pushing air pass my raid array to keep those drives ice cold.

The fan itself takes 12v 0.34 amps or 4.08 watts.

I can't find anything that meets my needs.

I'm looking for a master control, not individual control. Something like APEVIA FC-01 Multi Fan Speed Controller but can handle more amperage, 1.2a is low.

I was thinking about building my own, but I'm not an electronics engineer so I'm not sure where to begin.

Any ideas?

what would I need?