PSU just for lights

Strudul · 11 Jul 2010 at 17:35

I was wanting to put some cathodes behind my TV e.t.c. I have multiple spare PSUs and I was wondering.

Is it possible to use an ordinary computer PSU, but link it up to only cathodes with the 4 pin molex connectors. Or is this dangerous or something ...? It will only be using a very small amount of power (3W per cathode I think), but the power supply is very big in comparison (350W)

Thanks

Lonz · 11 Jul 2010 at 17:36

That would probably be the least cost effective way of doing something like I could think of...

Strudul · 11 Jul 2010 at 17:42

Why isn't it cost effective. I am not purchasing more PSUs. And i believe PSUs only give out the required amount needed. e.g a computer needing 500W of power with a 1000W PSU. The PSU only gives the computer the neccessary 500W. Or am i mistaken ?

It is saving me from going out and buying another way to power the cathodes.

Marvin · 11 Jul 2010 at 18:46

You need to short out the 24 pin connector to start the PSU up, but other than that there's no problem. (Though some PSUs will cut off if there's not enough load on them). Those with watercooling loops will test the loop out first by plugging only the pump into a PSU then following the above.

The two wires you'd need to short are (a paperclip or staple would do) the green one and any black wire.

These are the specific 'startup' pin (green) and a ground wire (black). You can see diagrams on Wikipedia.

Marvin · 11 Jul 2010 at 18:48

Oh and yes, the PSU will only supply as much as necessary (obviously) and therefore only take as much as necessary (though slightly more than output as they are not 100% efficient). This brings me to the main reason you may not want to though: computer PSUs are very inefficient at low power, and the eff peaks at around 60-80% load (ish). Still not that much to worry about.