Low voltage power supply, ventilation & lighting

One thing that has been lacking since the first build of the rack is ventilation. With both sets of doors closed, the inside can get quite warm, especially when iron is turned on. Not any more though, having just completed the installation of 2 active ventilation zones, lighting and a low voltage power supply system complete with rack-mount control panel.

Air is drawn in at the bottom of the rack by 5 quiet 80mm 12v fans, positioned behind a perforated 2U panel inside the front panel of the base. The air is blown vertically into the cabinet from the bottom through a similar 1U perforated panel. Although the draught is barely noticeable, the difference it makes to temperatures at the front of the rack is significant.

With this ‘air curtain’ alone though, the back of the rack still gets very warm. To solve this I’ve installed a relatively huge 200mm ‘Big Boy’ fan into the newly-added top of the cabinet. This sucks out the warm air and dispenses it into the containing room. Together these fans keep the entire cabinet cool.

To power the fans I’ve used an old ATX power supply. In order to make replacement easy when the supply fails, no modifications have been made to it. Instead, I bought a 20-pin molex connector so that I could just plug the ATX connector straight into my system.

The PSU is connected to 4 switches that are mounted on a 1U blanking panel in the front of the rack. I wanted some fancy switches, so I splashed out on some nice chromed illuminated ones from China (via eBay). There’s one green DPDT switch, which switches the PSU on and off, and three blue SPDT switches which control power to the two fan systems and some lighting.

The lighting illuminates the front of the rack, and is there purely for decorative purposes. I had considered using cold-cathode tubes, but the seller that I got the switches from also sells strips of LEDs encased in a flexible transparent rubber-like substance. They are sold in various lengths, but I thought 96cm would be OK for what I wanted (at the time I bought it to experiment with, thinking that it could illuminate the wall behind my desk). This strip is now mounted on the left-hand front door.

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