n00b question...i have a fan that runs on 12-24v is there a way that i can get more then 12 volts from the power supply so i can have a high and low setting? could i take two 12v lines and put them into one to make 24v? i'm not really sure if you can just add voltage
I know you can make 17 volts by taking a +12v line and use it with a -5v. So if there are any -12 volt lines you can use them. However, you will have to look in the big ATX-plug. i am not sure there is such a thing as -12v.
you cvan use -12v as ground to get 24 volts, however, most ATX supply's won't give enough power out on the negative voltage lines to power a fan...
No, the 12v that is comming out of your PSU is from just one regulator. Combining two 12v lines in a series, like two batteries, will result in a short to ground. Edit: You can try to trace the 12v regulator's positive tap and place another regulator of a higher voltage there so that you will have access to a higher voltage. Make sure to test the voltage of the tap because if the voltage going in to the new regulator is too low, then the new regulator will be thrown off regulation.
He should take a +12v wire form a molex and connect to the + pin on the fan. then he would take -12v from the ATX-plug and connect to - on the fan. the -12v is blue, according to this: http://www.thetechboard.com/tutorials/atx.php Remember not to cut the line. the mobo will still need its -12v
I don't think so... unless you have ISA cards... anyway... i still don't think the -12v will have enough power.,..
Sorry, i missed your first post.. I must admit i have never seen this done. but i have seen people "overclock" ( ) their 12v fans to 17v by using the -5v. I do not know how much power the -12v gives. I do not know how much the fans use. I can not think of another way..
i have a 350W PSU and it says 0,8amp on the -12v rail and 0.3 on the -5v rail... (hey! finally i have found something that is USEFUL with windows ) i don't know how much your fan draw though... just remember that the fan will putt a bit more at startup...
I have 2x 24V 1A fans running on an old modded ATX using the +12V and -12V (blue wire) lines. I have to switch the PSU on for 'bout 30 seconds before switching on the fans or else to PSU trips...
I've been doing things with 24v fans for a while. This is definitely possible.. however my 24v fan draws 8 watts as such, if I try to turn it on when it's not spinning, with no other load on the psu, the psu shuts itself off. Since that's no good, I came up with a solution. If you have the fan wired to a 12v/off/24 switch, you can spin up the fan with 12v at first, on regular gnd and +12v. the molex lines can handle the draw- then you flip it to 24v and it takes less power to get up to top speed and the psu won't shut off. Alternatively, you can use a rheostat to slowly bring it up to speed. It's not that hard Everybody's got it right though, its the blue wire on the atx plug. a multimeter does wonders.
suuure.... you want to wire the -24v and ground wires to a switch that switches between -24v and gnd. so.... a dpst switch with 3 prongs on the bottom. the middle prong will output whatever the switch is set to.
