Power supply plugs
 

Just realised that while trimming away unneccesary cables from the PSU, as I don't use a floppy drive I got rid of the only connecter for it :( As it turns out my water pump needs one to turn itself on, so, I'm wondering, which cable is 7v, which one is 12 (I'll get the soldering iron out).

Cheers

Re: Power supply plugs
 

The connections and power rail coulours are the same as for the hdd power connectors.

red - 5v+
Black - Grnd
Black - Grnd
Yellow - 12v

HTH

Re: Power supply plugs
 

Cheers, no idea where I got 7 Volts from.

Re: Power supply plugs
 

you probably heard about the fairly well known mod for fans that involves combining the 5 and 12 volt lines which gives you 7volts to run the fan at low power and therefore low noise/performance (http://phlux.co.uk/articles.php?aid=38&page=2) i'm not an electrician so don't ask me to explain the science bit ;)

Re: Power supply plugs
 

The 5 v line is 5v above 0v, so if you use the Red 5v line as the fan 0v and the Yellow 12v line as the fan 12v, you then get the 12v minus 5v which = 7v.

As both are capable of supplying enough current to to this there should be no PSU problems, however, the fan is then running at the minimum if not under it rated usable voltages & this may reduce its lifespan.

Also, the amount of airflow that the fan passes will be reduced as it is operating at a slower speed.

But what the heck, if it works & does the job then go for it.

Re: Power supply plugs
 

I dont think I would fancy doing this to my pc ! the principle is fine with a resistive load but since most fans are coil pulsed (inductive) then the voltage will fluctuate with the load and drag on the fan....

Why not build a pwm speed controler to do it... The comps would only cost a couple of quid in Maplin !

P.S. Sorry for hijacking your thread Bifta !

Re: Power supply plugs
 

As my old physics lecturer would say "It's not voltage, it's potential differance"
p.d. makes it so much easier to understand how you can get things like 40V from a 60V and 100V terminals (the potential difference between the 2 being 40V)

Re: Power supply plugs
 

huh? You lot are making my brain ache

Re: Power supply plugs
 

This thread is :shocking: :D