Switch to control case lights

[PHTC]

Hi all, I have an unbranded case which has a door at the front which lights up when the power is on, I love the look of it however would love to be able to turn it off at night. I was wondering if anyone knew about how I might add a push switch to control the lights.

The light is powered through a 4 pin molex connector which then passes through allowing a device to be powered through another molex connector, however I dont have a device connected to this spare one meaning if i could cut the connection via a switch a loss of power through to the remaining connector wouldnt matter.

So if anyone could help me by telling me a) if this can work, and b) how i might go about it (ie connect which colour wires to the switch)

Thanks again.

[TheAnimus]

dead easy to do, first off find a switch u like the look of
www.rapidelectronics.co.uk or www.maplin.co.uk or similar.

Do you know if the lights are LEDs or a CCFL or something else?
I had some LEDs on a case that pissed me off when trying to sleep, so i used an LDR (Light Dependant Resistor) an op-amp set up as a schmitt trigger, to control the brightness. The result was, if room light lights are on, if room dark, lights are off.

an example i've quickly googled is:
http://www.uoguelph.ca/~antoon/circ/sensor2.htm

[RavenNight]

That looks great though I'd be wary of using the rela yin that cicuit digram when the fied collapses it generates one hell of a pulse. I've been caught out many a times by evil people while i'm fiddiling with a protoype, it really hurts!

[TheAnimus]

in the google schematic there is a diode accross the coil that drives the relay, thats to prevent a dangerous discharge that could damage the transistor.

If its just LEDs you could drive directly from the output of the OP-AMP probably!

[PHTC]

Thanks for the reply, looking at the schematic it doesnt seem that difficult so i'll have a go and post the results on the modding section, i have a few led's on a door panel and a few led fans, so i'll swap out some of the fans for non-led ones and have the others operate under control of the switch (while monitoring system temp just in case)

I like the idea of the light dependence, would've never thought of that myself but i think i'll just stick to a normal push to make/break switch.

Thanks again all and i'll post the results.

[TheAnimus]

a toggle switch is the easyest, as for using a push switch, thats different kettle of fish, as you want it to "latch" see:

http://forums.hexus.net/showthread.php?t=67786

[Butcher]

That looks great though I'd be wary of using the rela yin that cicuit digram when the fied collapses it generates one hell of a pulse. I've been caught out many a times by evil people while i'm fiddiling with a protoype, it really hurts!

As TheAnimus mentions, D1 in the circuit prevents that sort of thing.

[RavenNight]

Lol, but if you happen to be touching the board when it goes, wham. I'd also assume that Diode dumps the pulse onto the 12v rail, which may be connected to the PSU, is that safe?

[Butcher]

It shorts the relay during the pulse, which means the current just gets turned into heat in the relay coil.