How-To build a fan regulator with parts list and pictures — Christoph Jadanowski aka FrankisGER
Disclaimer: Neither the Author or Overclockers.com takes any responsibility for any damage if you attempt what is shown here. This article is for information purposes only.
There´s probably no need to explain what can be done with a fan voltage regulator. Some time ago, I built a LM-317 based voltage regulator (click opens the how-to). The LM-317 is an adjustable linear voltage regulator. My circuit was made from 4 parts (1 resistor, 1 potentiometer, 1 LM-317 and 1 heatsink) and costs about 1 Euro.
The advantages of this circuit are that it is very exact – the voltage stays the same no matter how many fans are connected to it – and in its power – a maximum of 1 ampere if the LM-317 is well cooled.
The biggest disadvantage of this circuit is that the voltage drop caused by the LM-317 is 1.25 volts. This means that the connected fans won´t get more than 10.75 volts if the regulator´s input voltage is 12 volts.
Today, I wan´t to show you a simpler circuit. The advantages are as follows:
- The circuit consists from just 2 parts (1 BC337-40,
- Cost: About 25 cents;
- Max. 500mA (enough for für 5 80mm fans);
- Needs no heatsink;
- Very easy to build;
- The adjustment is very exact and stepless;
- Provides the fans with a maximum voltage of 11.4 volts.
- 1 100k ohm potentiometer (size and type doesn´t
matter), cost: about 10 cents;
- 1 npn transistor BC337-40 (you can use any other npn transistor as long as it provides 500mA or more maximum collector current. When using a stronger one, you can use even more fans), Cost: about 15 Cents;
- Small piece of PCB (I used a 3 cm * 1cm piece);
- Some cables (depends on how much you need).
You should be able to get all of these parts at your local electronics shop or in every online electronics shop.
It´s really very simple to build. Connect one fan or more (up to 5; with a stronger transistor, even more) and adjust the voltage with the potentiometer. Be careful not to short-circuit the transistor by shorting the fan connectors (this way, the transistor will burn up or overheat). You can prevent this by adding a pre-resistor (to set the max. current) or by adding a fuse, but I didn´t want to go that far with this article.
Also be careful on where you mount this circuit, because the underside carries 12 volts and ground – you´d best glue it onto some piece of plastic. I built the circuit this way (ghetto!):
It´s one of the smallest fan voltage regulators, i´ve ever
seen. For me, it was a way to get rid of some parts I had lying around
and I hope this circuit can help you. If you are interested in a similar,
but temperature-regulated version, look at this page: www.heatsink-guide.com. The German version of this article can be found here: www.extremepage.at.