Can I join the 5V with the 3.3V giving 8.3v?

If so, how would I do that? Run a lead from both the 5 and 3.3 joined to give 8.3?

In case you are wondering, power for pelts.... The amps available from the 5 and 3.3v is very high. If I use the dedicated PSU for pelts only, then I would have a lot more power available.

you can run two psu's in series. very important> they must both be isolated from frame grounds. undo the screws that hold the mobo of each psu down, if there are contacts on them at the mounting holes you must totally isolate them. if there are wires (usually green) going to the case of each psu, they must be cut. then you will want to test each with an ohm meter. put the test leads across a negative wire coming from each psu and the frame of each individually. if the grounds have been completely broken the needle should not move. (if it is digital it will stay at zero). if there is still a ground no matter how slight the needle will move. find and isolate the ground.

then you can run the two psu's in series. plug the +5v into the positive side of the pelt using psu #1's +5v lead. then take the negative wire from the second psu and connect it to the +3.3v output on the second psu. then take the negative from psu #2 and hook it to the negative of the pelt. this will give you the voltage you want 8.3v at the same amperage as one psu would provide.

if you are looking for more amperage, the same ideas with two psu's can be used to create more amps at the same voltage. in this case just attach the +5v from psu one to the + side of the pelt. then connect the +5v side of the second psu to the + side of the pelt. connect one negative from each psu to the negative side of the pelt. this will give more amps at the same voltage (5v at double the amps).

the first method is called wiring it in series, the second method is called wiring in parallel. if you do not isolate the frame grounds on both psu's your very likely to burn one or both up if you are doing the first example or running them in series. so make certain that each of them are isolated from frame grounds and you should have no trouble using this method to aquire the voltage or amperage you need.

Wouldn't it be safer to just connect to the +12V and +3.3V to get 8.7V?

if i were you before i do anything is run a voltmeter across all the wires and check the voltages. i haven't done it to any PSU's yet but i will next time i have an extra one. i've heard you can come up with some wierd voltages with just one PSU~RCTG

infinitwisdom

I am talking about using one psu dedicated to powering my pelts at 8.3v by joining the 5v and 3.3v somehow?

larrymoencurly

How would joining the 12v and 3.3v to get 8.7v? I am interested.

RCtruckguy

Always would... too many accidents

no what i mean is take it out of the case and short the green and a black. then connect the mulitimeters leds to various wires. ex connect the pos wire to a 12v wire and the neg to a 3.3v wire. or maby a 5v and a 3.3v. get my drift?

larrymoencurly is telling you to do almost what i told u to do. hes just telling you to use the +12v on the + or - of the pelt and the +3.3v on the remaining + or - on the plet and you'd get 8.7v theroicly. (lol i'm a terrable speller when i just got up lol) but i'd make sure its 8.7 and not 15.3 or you might fry your pelt. or if you checked every combonation of wires you migth find a voltage better suited to your task. i've seen alot of guys use the +12v and +5v to get 7v and run thier fans off of it. good luck~RCTG

Oh ... I see ... Thanks RCtruckguy

no problem just spreading the knowlage...~RCTG

How would joining the 12v and 3.3v to get 8.7v? I am interested.

Click to expand...

When useing two live wires of a PSU the lowest powered one gets used as an earth. the 7V mod use the 12V as the live wire and the 5V as the earth, they share the same 'bus'(?) though, if the 5V rail gets more ampage pulled through it the output to the 12V rail goes up as well. I don't know if this affects/is dependant on the 7V mods ability to work though...

So 12V minus 3.5V will give you 8.5V (aprox). why not just use a potentiometre to vary/regulate the voltage you want?...

PS. If the PSU is powering the TEC only you need to put a (highish value) resistor or something to draw load on the 5Volt rail as well. like I said above the 12V rail only goes up when there is current being drawn on the 5v rail, so the 12v won't be able to draw the max ampage, you might not have enough current to power the TEC without a load on the 5V rail...

your thinking of AT PSU's, i've built plenty of always on ATX PSU's,wicth is how you'd use them for TEC's, and you don't need to put anything on the other rails.

i was experimenting last night with my PSU and i got 23v,6.5,6,10,17,1.7,and 8.? all of those useing 1 psu. though because of the lower powered rails i don't know whatyou can run off of them~RCTG

No I'm not thinking of AT PSU's. the current draw of the 12V rail is tied in with the 5V rail. there's a link to a mod for adding a resistor (Ithink) to the 5V molex to increase the PSU's 12V output, I'll try and find it...

PS, watch your 12V reading go up when you tax the CPU with a stress test proggie to see what I mean. the 5V will go down while the 12V rises...