relay and power question

[DeepFried]

I'm working on a small PC mod and I wanted to find out if I'm going about this the right way or if I'm going to end up frying something if I do this since my electrical knowledge is pretty limited.

The concept is this: I have a small 6vdc flourecent light powered by a generic 120vac-6vdc transformer that I would like to power on/off when the computer is powered on/off instead of having a separate switch. I would like to use a 12vdc relay to accomplish this. There is a nearby 12vdc case fan which, if my thinking is correct, I should be able to splice into to provide the necessary voltage to the coil in the relay. If the 6vdc lead is running through the relay, then when power is supplied to the 12vdc coil, then the relay should close the circuit for the light.

1. Will this work?
2. If not, what should I do instead?
3. If it will work, will it create any interference or other "funky" power issues?

Thanks in advance!

 

[Killbat]

As long as this case fan isn't powered by a motherboard header, you should be fine, BUT...
I think you should consider other, more integrated power sources for your light. Two solutions that come to mind are 1) see if you can get away with giving it 5vdc from the PS itself, or 2) regulate 6vdc down from 12vdc from the PS. Either way, I think powering the thing off the computer's supply is a more graceful option than what you're planning.

 

[thevenin8888]

i agree with killbat to try and connect straight to 5vdc if it works or you can get 7v as well from ps not sure which colours offhand though,i think yellow and red use a small multimeter to test dv voltage if you can get one handy

 

[RossGr]

If I read the question correctly he is attempting to power a 12V relay, to swtich the 6V provided by the wall wart xformer. It that case, make a trip to your local RS and find a molex connector and pins. connect the relay coil to the molex connector via what ever lenght of wire you need to then you can simply plug into a PS molex connector without haveing to mod anything on computer. You will need to do a web search to find the correct pin out of a PS connector. Be sure to get the molex shell for the male pins. Sounds pretty straight forward to me.

 

[Menelaos]

The most elegant way, IMHO, would be to insert a 7806 (6V voltage regulator; 1$ max) along with some cap (100nF on either side + elco on 12V side) in between the molex connector and the neon. Check the curent needed, if it is below 100mA you can use 78l06.

Hope this helps,

Menel.

 

[DeepFried]

I ended up tossing it all out and getting a cold-cathode from azzo with a molex connector on it