Look what I have found!

[Ct. Strangelove]

In the everlasting search for the ultimately cheap and ez pelt power supply i have reached this point.

Peltier = 226w 15v @ 24amps

I have found a 12.6v @ 25amps transformer.

http://www.allelectronics.com/cgi-bin/category.cgi?category=790500&item=TX-12625&type=store

Capacitors from 50,000 to 210,000uF.
http://www.mouser.com/catalog/610/329.pdf

My initial thoughts are....

The transformer will get pretty darn warm even at the draw of 21amps or so. Solution- Add a 486 cooler on it, sit it in direct airflow, or attack a WB to it and the WB be last in the cooling circuit.
The caps (50,000uF ~ 2" x 3.125") are fairly large. Nothing can be done about this. doh

Finding a brigde is the easy part.

What is everyone thoughts?

Whats the minimun uF rating of a cap to get good filtering?

 

[Daemonfly]

That transformer *shouldn't* get too warm. I have a 50A 15v powersupply and the transformer doesn't get that warm at all. It's the diodes that get hot!!

If I remember correctly, my PS has 50,000mfd caps in it. (it's buried in my closet right now).

If size is a problem, you can always parallel a lot of smaller caps to get the same mfd rating.

 

[Since87]

The transformer Ct. Strangelove's talking about is likely to run fairly hot powering a 226W pelt.

It will be running close to it's max ratings and probably much hotter than a transformer rated at 50A.

As far as the caps are concerned, to keep the ripple within the 10% value I have seen recommended for pelts, the total capacitance would need to be 133000 uF. You should use 25V rated caps. So that puts you at using 4 of the 41000 uF 25V caps, priced at $15.14 apiece. Throw in $20+ for the transformer and diodes and you are over $80. The 350 watt supply shown here makes a lot more sense at $70.

 

[Toysrme]

You could also try going to a local school/university/salvation army.

I had a friend's mom bring me home 2 AMD 133 computers. Ofcource niether worked, but the EDO ram went to my printer the monitors are used with 2 other computers. The HS's are for chipsets and both power supplies output 20A.

Try that

Alittle time being creativee on where you get stuff and end you up something for free <g>

 

[Ct. Strangelove]

Well, i ordered the trans, brigde and caps. I will test them with my pelt soon and post the results. "133000 uF" was a statement of cap rating i need. Is "133000 uF" correct and not a misprint? I am going to try at 60,000uF. I that is horribly wrong, then I will order the proper caps. Its not really about the cash. I will WC the trans. Well I will find out in a week or two

 

[Since87]

133000uF is correct for 10% ripple. 60,000uF will give you over 20% ripple. It will work, but it may age your peltier prematurely.
I've seen it recommended to keep the ripple below 10%. I doubt 25% ripple will kill the pelt very quickly, but I wouldn't want to risk it myself. Does your MOBO shut down if the CPU gets too hot?

 

[Ct. Strangelove]

I am not sure. Why you ask? Inthecase of the pelt dieing?
I have a LCD temp sensor with high/low setable marks. The diode is drilled into the cold plate. When the cold plate hits 99F the whole comp shuts down via relay.

 

[Since87]

Yes, in case of the pelt dying.

I would want to be sure the machine would shutdown if the CPU or coldplate got hot.