Hi there,

I am after some advice for what I think must be a very simple project...

I wish to cool my home audio cabinet using a pair of PC case fans (either 80mm or 120mm) - my idea is to use one fan to draw cool air into the cabinet, and one to exhaust warm air, creating better air circulation.

I expect to be able to drive these fans with a cheap off-the-shelf power 'brick' that can output 12V.

The fans' inputs are rated thus:

80mm: 12V/0.72W
120mm: 12V/1.2W

Basically, I'd like to know:
1) How best to connect the fans to the Power Supply (series/parallel?)
2) Advice on what figures to look for in a suitable Power Supply
3) Whether I would need additional components in the circuit

Any other general advice gratefully received!

I'm a complete electronics newbie, but I can at least handle a soldering iron...

Many thanks in advance,
NIck

 

A wall transformer rated at 12 volts DC and 250 ma should be able to handle the fans. Connect the fans in parallel.

Be sure you identify the polarity of the leads from the wall transformer. The easiest thing to do is to cut off the connector and solder the leads to the fan wires. The red lead from the fan is the positive lead. You could also use small wire nuts, but they look less professional than solder and heat shrink tubing..

 

A worthwhile elaboration would be to incorporate a speed control to reduce noise which could be controlled manually or by a thermostat. Although an adjustable output power supply may provide all the control you need.

 

You might get better results by using both fans to exhaust air from the top of the cabinet, and simply provide adequate sized holes for cool air to enter near the bottom.

You might find the noise generated by a couple of PC fans operating at full speed to be annoyingly loud. You could use a relatively simple LM317 voltage regulator IC with a couple of resistors and capacitors to adjust the speed of the fans.

If you wanted to take it a step further yet, you could use a thermistor to get the temperature inside the cabinet, and adjust the airflow as necessary to reduce it. This obviously complicates the circuitry.

 

Blocco beat me to it

 

Thanks to everyone!