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With all the fans in this machine it it getting (ahem) a little noisy. The sound doesn't bother me but trying to talk to anyone that is not standing right next to me is all but impossible. So, I figured I may as well add a "BayBus" (a series of switches to turn cooling fans off and on) to the setup. |
Took a trip to local Radio Shack to round up some parts. I want to use dual coloured LEDs to indicate fan status - off and on (heh, like you can't tell from the sound). Can't use two seperate LEDs since the only space remaining is a 3.5" drive cover. I found the DPDT switches (RS part# 275-626) and the panel mount LED holders (RS part# 276-079) but the only bicoloured LEDs they had were these two lead devices (RS part# 276-012) that change colour depending on the polarity. Bicoloured LEDs normally have 3 leads: a common cathode and 2 anodes. But....thats all they had and I don't like to wait so they will do. So I sat down with a pen and notepad and a beer and came up with this:
The drawing makes the bicolored LED appear as two LEDs (and that would work too) but it is one component. In essence, this is similar to a three-way switch in your house but the switches here are tied together.
As usual, out with the metal ruler and mechanical pencil and drew a grid on the cover to keep everything lined up evenly. I decided to leave a bit of a gap between the switches for intakes and exhaust.
Next, I drilled out the holes for the parts and soldered all the components and jumper wires together. The fans are connected with female Molex jacks and incoming power is a male Molex plug.
Its a little messy looking but there is not much you can do with direct soldered components. Note the physical size of the resistors. These are big 1/2W devices. I had to go this size since I am pushing the LEDs a little harder than spec - I like them nice and bright.
Finally, I used my glue gun to seal up the works. This will act as an insulator bewteen the components so they cannot accidentally touch together. It also strengthens the assembly to keep the solder joints from breaking.
Anyway, it works exactly as expected: with the switch in the "up" position, the LED changes from red to green and the fan turns on.
Here it is in action. The top (all red) image is with all the fans off. Usually proceding the words: "What? Say that again!" All on is when playing Quake, but I normally keep the big 120mms off when surfing etc.
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