Can i mod things onto my psu?

Defcon5 said:
basically ive got some led strip lights under my desk (its glass)

ATM they are plugged into the socket and have a switch to turn them on.

Can i make it so they turn on when i turn my pc on?
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If I understand you correctly. Then yes using a SPST DC (coil) relay. Rated with contacts above the wattage/voltage of the LED's. The primary coil connects to a molex 5v or 12v and neg. The normally open single pole contacts connect to the LED feed. When you power the relay the contacts will make and power the LED's. If its mains your messing with I hope you know what your doing. Get a little plastic enclosure and use some connectors, not much to it, quite simple. £5 for the bits.
 
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You can buy one in a highstreet electronics store. I can't say the name, rules an all that. SPST means. single pole single throw. Single pole is one set of output connections. Single throw means it only goes one way. You can use ones with DP double poles, but you only use the one. Now forget that. DC coil means the bit that does the work, the coil, connects to DC at its rated voltage. Best to get 12v. 12v is yellow on a molex, negative is black. When connected to the PC molex, the relay coil goes on. If the relay is normally open, then the coil pulls shut the contacts like a switch. Anything connected to the contacts will start to work. The good thing is that the voltage of your LEDS (mains or low voltage) cannot mix with the PC voltage. If your LED's are running on mains ask for the contacts to be rated for 230 volts. Also ask for spade(crimp) or screw connections with an inbuilt protection diode. Or you could get one with pins and use terminal blocks to connect the wires.

Its got four connections. On the coil side is + goes to the yellow. - goes to the black. Cut the feed wire for the LED's. On the contact side connect each of the cut wires to one of the contacts. Now put it in a small plastic enclosure so the live bits don't touch anything. Job done.



http://www.kpsec.freeuk.com/components/relay.htm
 
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fornowagain said:
It's about as hard as wiring a mains plug. It saddens me, it really does :(
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You seem to have specialist knowledge. For us mere mortals, the thought of fiddling around with something so dangerous ( to the computer if it blows) is worrying!!
 
fornowagain said:
It's about as hard as wiring a mains plug. It saddens me, it really does :(
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It's not quite as simple as you made out though- he would probably need a latching replay because applying constant voltage to the coils would probably cause them to burn out ;)
 
Trigger said:
It's not quite as simple as you made out though- he would probably need a latching replay because applying constant voltage to the coils would probably cause them to burn out ;)
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AC coils/solenoids can get real hot. DC's are wound with enough resistance to withstand the specified voltage without burning out. I've seen hundreds of DC relay coils energized for hours and they don't generally fail in the short term because of open/short coils, plenty of melted contacts. If you put DC in an AC relay at the same voltage it will overheat for sure.

Or for the more pedantic use an SSR, let it stay on all day.
 
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