Picture of AC Fume Extractor
This is a guide on how to build a simple 12 volt fume extractor that runs off 220V AC mains.

By running off mains, the fume extractor can run 2X fans at full power.
And all of the parts are easily available, maybe even stuff you have lying around.
The shell of it is an empty ATX power supply.

I'm keeping it short and simple, because I'm presuming that whoever wants to try this has basic knowledge of electricity.

If you don't know what you are doing, then this project is a bad idea - 220V AC CAN KILL YOU. If you wire it up wrong, you could short circuit to the metal shell and....

Hope you enjoy!
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Step 1: Parts

Picture of Parts

Apart from the box, you'll need:
1x DPDT switch, rated for mains voltage.
1x 220-12V transformer.
2x 3300microF polarised caps, rated for 25Volts or more.
2x 12V fans
1x bridge rectifier, or 4x power diodes.
1x three-prong socket like the one that computers use.

Lots of wire.
Soldering iron.
Screws, bolts, nuts.
Drill with metal bit.
Aviation snippers.
Clear pieces of plastic for gluing over the openings of the box.
Electrical tape.
Heat shrink.

And for the extractor tube:
Tin cans
Brown paper
Electrical tape

Step 2: The Box

Picture of The Box

Mark on the shell where you need to drill and cut.

You need:
1 hole for the second fan, plus holes for the screws
2 holes to bolt down the transformer. Place it so that it sits on the bottom of the extractor.
1 hole for the switch.

Step 3: Sealing up

Picture of Sealing up
ATX power supplies aren't really that watertight. But a fume extractor wouldn't work very well with a hundred leaks.

You'll use clear plastic to seal up as many of the holes as you can.
I used one of those clear fake CD protectors cut into shards.

This will increase the efficiency of the extrator by quite a bit.

Step 4: The circuit

Picture of The circuit
Here's how the circuit works:

The live and neutral lines are switched at the DPDT,  while the earth is screwed onto the chass to provide protection against short circuits.

The Live and Neutral are stepped down to around 12v at the transformer, then rectified with the bridge. The caps filter it and boost the voltage slightly.

The 2 fans are connected in parallel.

And my drawing is very beautiful, if don't say so myself...
naufanmaker3 years ago