36v Dc Psu

[_N_]

ok,

I need a 36v DC PSU, I can make one, which is OK, but before I do, is there a way of getting 36V out of a computer PSU?

This is what a 36V PSU would look like, pretty simple.
http://sound.westhost.com/p04_fig1.gif

The blue and yellow wire on the motherboard connector give you 24V, this is on ATX and AT PSU's, would it be possible to get the 12V line and hook it up in series with the 24V to get 36V?

Any suggestions welcome,

It needs to be able to deliver about 2A,
If you got one which you could sell, PM me, this is very unlikely cause they are very hard to find,

[mird-OC]

just an idea, if you're building this for an amp - see if you can scour up an old POS amplifier/tuner (they're everywhere and people quite often give them away). they contain everything you need for a 36V circuit aswell as something to house it in and some knobs and stuff usually too... just rip out anything you don't need, hook up your circuit and away you go :)

ghetto styles :p

[_N_]

:D
yep, I'll look around, I've only been able to find expensive second hand gear.

also, mine is already ghetto, so I can only improve on it,

I've been putting ads in T&E, so I hope I get something, :)

[Deviant]

My thoughts:

If the PSU's have any reference to earth, then as soon as you connect the the +ve of one supply to the -ve of the other the fuse will blow. Switch mode powere supplies don't need a referencr to earth, however I think all computer PSU do have an earth reference.

In simple terms, if you get a multimeter and place it between the black wires in the PSU's, and the chassis it will be a short circuit. So get any other PSU +ve and connect it to the -ve of another and it will see a short circuit to earth.

It works with +ve and -ve 12 volts because the use the same earth, and the -ve 12 is more negative than the earth if thats makes any sense.

That circuit diagram you show uses some big components, and is way over the top (high current, huge components, very expensive transformer). I'm going to do a little research for you.

[_N_]

that PSU up there is a dual, which I don't really need,

I was thinking of using a computer PSU, and just stepping the V up from 12 to 36V, that would seem the easiest and I also got spare 300W ATX and 230W AT which I never use, so that would look simple.

BTW, I flipped thru T&E and the Amp's under 100$ are like 25W, which is nothing,

[Deviant]

So are you talking DC to DC converter, output 36v at 2A. Lets say 2.2A for a 10% room to move. 2.2*36=79.2 watts. Now convert that to 12v, and you get 6.6A at 100% efficiency, ass 20% for losses in the converter = 7.92A which should be ok on a 300W PSU.

Converters arent easy, not at that kind of voltage and current.

If you are thinking about adjusting a PSU to output 36V, it just wont do it.

It might be easier to make a PSU like this from scratch:
http://www.aaroncake.net/circuits/supply6.htm
just change the components for higher voltage.

but if you look at DSE, the only transformer thay have suitable is 42.5 @ 60VA or 1.4A. which costs $34-95 (2001 catalogue), not enough current. Have to look elsewhere.

Have a look at a simple converter circuit:
http://www.aaroncake.net/circuits/6-12conv.htm

This isn't going to be easy, to redesign this, what do you need it for?

[_N_]

56W amp running on this little IC: http://www.national.com/pf/LM/LM3876.html#Datasheet

this is the amp:
http://sound.westhost.com/project19.htm

except his is a bit differnt and on the photo he has two for stereo, I only have 1 which will be used to power my subs which don't need stereo, or If I do, I can always get a second one.

[City_Idiot]

Having a pile of PSU's sitting at home there is a guide out there for rigging psu's up together and i manged to get 120v@10 amps for afew dyas till i turned it off
all you need to do is make sure all the gound lines on all but 1 of the psu's don't earth, uselly it's a screw by the blck wires. you connect all the psu's in either parallel or series or a mix (ie/ 6 psu's 3 in parallel X2 so you get 24v@20amps) after you modding the psu'd you connected the +12 to the -0 on the psu's together in a daisy chain and you're done i will try and find it but i was going to build a cutsom housing for it and get 36v @ 50amps or so for some speakers but i have run out of $$$ for it

[_N_]

yeah, I was thinking of running a 24V of the 300W ATX and then have 230W AT supply the extra 12V,
and then connecting them in series should provide about 36V (more like 33-34V).

I'll go and try that now, if something blows up, oh well, it's all part of learning,

BTW, I electrecuted myself on an open PSU by putting my finger by accident on the live 230V connector, :D

[City_Idiot]

Found it on Procooling!!
http://www.procooling.com/articles/html/linking_multiple_psu_s_as_one_.shtml

[_N_]

thanks,

this should solve my problems,

I just have to be careful working with high W.

:)

[City_Idiot]

yeah just a word of warning upgrade all the PSU wires (+12 -0 etc) cos i dont think they like more than 24v or 15amps


*looks are burn mark on floor from wire @ 12v@80 Nuclear Power Tower Project*

[_N_]

true, forgot about that, it's only gonna be 10A 36V, but still have to think about that.

I read that article a couple of times and it makes heaps of sense.

eg, normally your PSU has the V relative to the ground, but, by removing the ground, the V becomes relative to the PSU connected to it.

This is one of the best advice I got from here, thanks, this has saved me heaps of trouble by not having to buy an expensive 36V PSU or having to make one.

:) :) :) :)

[City_Idiot]

* Accepts NO reasonability For Burn’s TO Either Human’s or Property Nor for Power Outages to House’s, Streets or City’s Due to Crazy GETTO speaker power supplies *[/SIZE] :D :D :D


Glad i seem to have helped some out, any sparkeys wanna pick throught that guide and see if it's all sound??

[Deviant]

It's not the wire insulation that will break down, thats sure to go heaps higher, it's capacitors you have to worry about.

Thats a good idea to disconnect the earths, I can't see why it wont work.

A note from experience, some PSU don't put out maximum load on the -ve supply rails until there is a current draw on the 5 and 12 volt rail. So to get -12v you may need a resistor on the 5V rail. I've been caught out with that before, but it's not all PSU's.

[_N_]

i tried without disconnecting the ground and you get the buzzing sound coming out with 0V.

something extra: if you get a multimeter and connect it accross the +12V on one PSU and the 12V GND on the another PSU, you will still get 12V, even using two PSU's.

Also my Amp will only use max 60W, so can't see much damage done by overloading, :D :D

[Deviant]

Have a look at this N, the connect two PSU's in series to run a peltier, and explain how by diconnecting the earth.

BTW, no earth on metal chassis is illegal in NZ, and almost certainly void any insurance on your house. If you use an isolating transformer, you get arround this. Isolating transformers have no earth so you don't need to disconnect anything, and safe to use.

http://www.pureoc.com/eXtremeCPUOC_1.asp

[_N_]

baiscally what that article says is that you don't have the PSU grounded in the wall, which is somewhat hard,

I should probably use an isolating transformer, i'll try it out without grounding one PSU and will tell you how it goes after UNI today.