A simple DIY equipment cooler

If you’re like me, and you like huge stacks of stereo equipment, you may be wondering how to keep it cool! My quad-amplified system requires four amplifiers, and I can’t really give them all enough room to breathe. Plus, they look pretty sweet stacked on top of one another!

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Problem is, the heat from each of these components adds up quick! The topmost amp gets really, really hot!

What’s needed is just a slight breeze… Just enough to keep the air from stagnating. Lots of people use laptop coolers, but these are meant to lie on top of or under the unit, and only work for one component, like a big AV receiver.

But what I needed was a light breeze across the tops of all my amps. Not finding what I needed on the internet, I decided to just build my own.

First of all, we need a very very quiet fan that can still move a decent amount of air. After reading some reviews, I chose this 230mm computer case fan from BitFenix.

I made a clip-on bracket out of a binder clip and some aluminum sheet metal, which can be bent to angle the fan. Welded wire keeps cords out of the spinning blades. Rubber bushings prevent vibration transmission.

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For the power supply, I recycled an old 12V wall-wart, and made a simple variable fan-speed controller with an LM7805 regulator mounted to an old TO-220 heatsink. The circuitry is encased in epoxy putty. It’s ugly, but it gets the job done. Don’t look!

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The circuit is straight out of the datasheet for the LM317 variable regulator, except I am using an LM7805, which is supposed to be a 5V fixed-voltage regulator. In actuality, the LM317 and LM78xx regulators are the same parts except for the internal reference voltage. The LM317 is 1.3v, and the 7805 is 5V, so if you feed it 12V, and float the ground pin with a potentiometer, you get a regulated voltage adjustable from 7V to 12V. This voltage range is perfect for the application, as anything lower than 7V may not be enough to spin up the fan. Lots of computer fan-speed controllers use exactly this circuit. See this link at Ptarmigan labs to learn how to wire the regulator….

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The noise level is just about nil. You need to put your ear pretty close to even hear it running! And the breeze is just enough to keep the amps running warm to the touch, about the same as when they stand alone.

Total investment: 20 bucks and two hours.

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