Power sloution for two 172W pletiers for less than $200?? - Page 2

Miss_Man · 11-17-2001, 07:16 AM

Hi. Anybody linking 2 AT power supplies to power a peltier? Does it give a constant amount of ampage to the peltier? Can it be run long term? Must they be the same brand?

futRtrubL · 11-18-2001, 02:10 AM

Where were you guys getting your toroidals? I've been looking for ages for good small toroids. They're the only things keeping me from pelting.
Cooling is good, I have two rectifiers left over from a previous project and large car adio caps can be gotten easily.

Edward

Butcher · 11-18-2001, 01:23 PM

I get mine from RS Components but you might want to find a closer supplier. They sell up to 1000VA (iirc).

futRtrubL · 11-20-2001, 01:07 AM

Anybody know of US supliers?

Edward

GigaFrog · 11-29-2001, 12:25 AM

Look at this puppy:

All Electronic

12.6V at 25Amps, for $20.
Build your PSU around that (thats what I am planning to do).

No regulation though

Butcher · 11-29-2001, 04:58 AM

that link didn't work

GigaFrog · 11-29-2001, 11:34 AM

Here is the link, copy-paste in the address bar of your browser:
http://www.allelectronics.com/cgi-bi...790&type=store

And go to page 3. There is a 12.6V 25Amps transformer for $20.

I don't know why my previous link did not work

Butcher · 11-29-2001, 02:10 PM

Yeah that'd do the job, a 12.6V transformer when hooked up to a rectifier and suitable smoothing capacitors will yield around 16-18V, might want to stick a regulator on that

resago · 12-04-2001, 11:22 AM

I'm looking at doing this, what rating bridge rectifier do I need, they have them on that site as well..

also how big of a capacitor 10,000uf ??

where can I find one of those??

the bridge rectifier and transformer will only run me $25 so far. Are the large capacitors the most expensive part?

I'm basing my setup off this site http://www.ioport.com/peltiers.html

resago · 12-04-2001, 12:16 PM

hmm, just read the article mentioned in previous page, so I just get the biggest rectifier I can (35Amp 800volt) and If I want to power that 220watt pelt with 15v@20A, I need about 90,000 uf capacitance?
correct?

DAMN thats a big capacitor!!!

Petrus · 12-04-2001, 03:54 PM

Is it possible to se several smaller capacitors in paralell, so their combined capacitance equals 90,000 uf?

Butcher · 12-04-2001, 03:59 PM

Yes you can use caps in parallel, check the maximum ripple current, the sum of these should be at least equal to your peak current. As for the bridge, a unit rated to double the voltage and current required is usually fine, it will be BIG - I have a 35A unit with a 1/4" mounting hole!

resago · 12-08-2001, 06:27 PM

found everything I need, here are the links:

120,000 uf cacpacitors http://www.meci.com/default.asp?mode...s&category=505

50 Amp Bridge rectifiers http://www.mpja.com/listall.asp?dept=111

12.6V 25AMP Transformer http://www.allelectronics.com/cgi-bi...625&type=store

$32 before shipping, woohoo!!!

[ 12-08-2001: Message edited by: resago ]

resago · 12-09-2001, 09:39 AM

2 of those places have a $15 and $20 minimum order, so if anyone wants to go in together, let me know.

GigaFrog · 12-10-2001, 02:57 PM

These capacitors will not handle the voltage.
The transformer will generate 12.6VAC, which after rectification, will give 12.6V * SQRT(2) = 17.8VDC max.
You need a 25V capacitor if you want it to last longer.
At MECI, check this part number: 191-2100

I thought MECI also add bridge rectifiers, but I couldn't find them.

Butcher · 12-10-2001, 06:47 PM

Don't skimp on the voltage for caps, you DO NOT want caps that big exploding on you.

resago · 12-10-2001, 07:48 PM

part # 196-0020

10v, 450,000uf , 2 of these in series will yeild

20v, 225,000 uf. $8 total.

of course there's still the minimum order thing.

Butcher · 12-11-2001, 04:54 AM

Didn't think the law of potential dividers works for capacitors...

resago · 12-11-2001, 12:05 PM

guess I'll find out, can't be any worse than getting hit with PVC pipe from an exploding potato gun.

GigaFrog · 12-11-2001, 11:29 PM

Actually, you take risks by putting capacitors in series. The voltage will be balanced only by their leakage current, a parameter that varies too much unit to unit to be reliable. In English, that means that one of the capacitor will have more voltage than the other.
You need to balance the voltage with additional resistors, 1 in parallel on each capacitor. 1K should be enough.

In my opinion, it is simpler and safer to spend a few more bucks and get the good capacitors.

resago · 12-12-2001, 10:18 AM

true. I've actually got some 55v units from an old HP computer (the kind that used to take up an entire room) but the capacitors are rather large 4" X 9". I was looking for something more compact, but I guess I'll use what I have.

resago · 12-12-2001, 11:20 AM

I was thinking, since a peltier is a solid state device, I really wouldn't need THAT much smoothing would I?

I mean, I could probably get away with around 50,000 uf for 25amps@17v, maybe even less.

I'll test and see if it makes a difference, I have several of those large capacitors, I'll just wire up one at a time and see what difference it makes in the temps on the pelt.

[ 12-12-2001: Message edited by: resago ]

futRtrubL · 12-12-2001, 03:58 PM

I talked to a tec at a pelt company and he told me that while higher ripple won't affect cooling, it will affect lifespan quite badly, especially if used around Vmax but also at lower V.

Edward

resago · 12-13-2001, 10:53 AM

ok, so how much capacitance do I need for near zero ripple?

4000 uf/amp was for around %15 ripple.
5000?
10,000?

[ 12-13-2001: Message edited by: resago ]

Kevin · 12-13-2001, 11:26 AM

Woah guys... this topic is GETTING HUGE! Mind if I lock it and start a new continuation thread? LMK...

11-18-2001, 01:23 PM	#28
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	I get mine from RS Components but you might want to find a closer supplier. They sell up to 1000VA (iirc). __________________ Once upon a time, in a land far far away...

11-29-2001, 12:25 AM	#30
GigaFrog Cooling Neophyte Join Date: Nov 2001 Location: NorthWest (French & US) Posts: 88	Look at this puppy: All Electronic 12.6V at 25Amps, for $20. Build your PSU around that (thats what I am planning to do). No regulation though __________________ Got water? Water cooled for 3 years. Safe with thermal switch. Now silent with fan thermostat.

11-29-2001, 04:58 AM	#31
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	that link didn't work __________________ Once upon a time, in a land far far away...

11-29-2001, 11:34 AM	#32
GigaFrog Cooling Neophyte Join Date: Nov 2001 Location: NorthWest (French & US) Posts: 88	Here is the link, copy-paste in the address bar of your browser: http://www.allelectronics.com/cgi-bi...790&type=store And go to page 3. There is a 12.6V 25Amps transformer for $20. I don't know why my previous link did not work __________________ Got water? Water cooled for 3 years. Safe with thermal switch. Now silent with fan thermostat.

11-29-2001, 02:10 PM	#33
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Yeah that'd do the job, a 12.6V transformer when hooked up to a rectifier and suitable smoothing capacitors will yield around 16-18V, might want to stick a regulator on that __________________ Once upon a time, in a land far far away...

11-17-2001, 07:16 AM	#26
Miss_Man Cooling Savant Join Date: Dec 2000 Posts: 151	Hi. Anybody linking 2 AT power supplies to power a peltier? Does it give a constant amount of ampage to the peltier? Can it be run long term? Must they be the same brand?

11-18-2001, 02:10 AM	#27
futRtrubL Cooling Savant Join Date: Jul 2001 Location: Kingston, Jamaica Posts: 204	Where were you guys getting your toroidals? I've been looking for ages for good small toroids. They're the only things keeping me from pelting. Cooling is good, I have two rectifiers left over from a previous project and large car adio caps can be gotten easily. Edward

11-20-2001, 01:07 AM	#29
futRtrubL Cooling Savant Join Date: Jul 2001 Location: Kingston, Jamaica Posts: 204	Anybody know of US supliers? Edward

12-04-2001, 11:22 AM	#34
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	I'm looking at doing this, what rating bridge rectifier do I need, they have them on that site as well.. also how big of a capacitor 10,000uf ?? where can I find one of those?? the bridge rectifier and transformer will only run me $25 so far. Are the large capacitors the most expensive part? I'm basing my setup off this site http://www.ioport.com/peltiers.html __________________ 2.4Ghz Compaq Workstation 2.8Ghz Custom 2700+ Custom still running 2000!!!! Help with Coding www.resago.com

12-04-2001, 12:16 PM	#35
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	hmm, just read the article mentioned in previous page, so I just get the biggest rectifier I can (35Amp 800volt) and If I want to power that 220watt pelt with 15v@20A, I need about 90,000 uf capacitance? correct? DAMN thats a big capacitor!!!

12-04-2001, 03:54 PM	#36
Petrus Cooling Neophyte Join Date: Jun 2001 Location: Umeå, Sweden Posts: 18	Is it possible to se several smaller capacitors in paralell, so their combined capacitance equals 90,000 uf? __________________ "Hard to se The Dark Side is"

12-04-2001, 03:59 PM	#37
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Yes you can use caps in parallel, check the maximum ripple current, the sum of these should be at least equal to your peak current. As for the bridge, a unit rated to double the voltage and current required is usually fine, it will be BIG - I have a 35A unit with a 1/4" mounting hole! __________________ Once upon a time, in a land far far away...

12-08-2001, 06:27 PM	#38
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	found everything I need, here are the links: 120,000 uf cacpacitors http://www.meci.com/default.asp?mode...s&category=505 50 Amp Bridge rectifiers http://www.mpja.com/listall.asp?dept=111 12.6V 25AMP Transformer http://www.allelectronics.com/cgi-bi...625&type=store $32 before shipping, woohoo!!! [ 12-08-2001: Message edited by: resago ]

12-09-2001, 09:39 AM	#39
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	2 of those places have a $15 and $20 minimum order, so if anyone wants to go in together, let me know.

12-10-2001, 02:57 PM	#40
GigaFrog Cooling Neophyte Join Date: Nov 2001 Location: NorthWest (French & US) Posts: 88	These capacitors will not handle the voltage. The transformer will generate 12.6VAC, which after rectification, will give 12.6V * SQRT(2) = 17.8VDC max. You need a 25V capacitor if you want it to last longer. At MECI, check this part number: 191-2100 I thought MECI also add bridge rectifiers, but I couldn't find them. __________________ Got water? Water cooled for 3 years. Safe with thermal switch. Now silent with fan thermostat.

12-10-2001, 06:47 PM	#41
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Don't skimp on the voltage for caps, you DO NOT want caps that big exploding on you. __________________ Once upon a time, in a land far far away...

12-10-2001, 07:48 PM	#42
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	part # 196-0020 10v, 450,000uf , 2 of these in series will yeild 20v, 225,000 uf. $8 total. of course there's still the minimum order thing.

12-11-2001, 04:54 AM	#43
Butcher Thermophile Join Date: May 2001 Location: UK Posts: 1,064	Didn't think the law of potential dividers works for capacitors... __________________ Once upon a time, in a land far far away...

12-11-2001, 12:05 PM	#44
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	guess I'll find out, can't be any worse than getting hit with PVC pipe from an exploding potato gun.

12-11-2001, 11:29 PM	#45
GigaFrog Cooling Neophyte Join Date: Nov 2001 Location: NorthWest (French & US) Posts: 88	Actually, you take risks by putting capacitors in series. The voltage will be balanced only by their leakage current, a parameter that varies too much unit to unit to be reliable. In English, that means that one of the capacitor will have more voltage than the other. You need to balance the voltage with additional resistors, 1 in parallel on each capacitor. 1K should be enough. In my opinion, it is simpler and safer to spend a few more bucks and get the good capacitors. __________________ Got water? Water cooled for 3 years. Safe with thermal switch. Now silent with fan thermostat.

12-12-2001, 10:18 AM	#46
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	true. I've actually got some 55v units from an old HP computer (the kind that used to take up an entire room) but the capacitors are rather large 4" X 9". I was looking for something more compact, but I guess I'll use what I have.

12-12-2001, 11:20 AM	#47
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	I was thinking, since a peltier is a solid state device, I really wouldn't need THAT much smoothing would I? I mean, I could probably get away with around 50,000 uf for 25amps@17v, maybe even less. I'll test and see if it makes a difference, I have several of those large capacitors, I'll just wire up one at a time and see what difference it makes in the temps on the pelt. [ 12-12-2001: Message edited by: resago ]

12-12-2001, 03:58 PM	#48
futRtrubL Cooling Savant Join Date: Jul 2001 Location: Kingston, Jamaica Posts: 204	I talked to a tec at a pelt company and he told me that while higher ripple won't affect cooling, it will affect lifespan quite badly, especially if used around Vmax but also at lower V. Edward

12-13-2001, 10:53 AM	#49
resago Cooling Savant Join Date: Mar 2001 Location: state of denial Posts: 488	ok, so how much capacitance do I need for near zero ripple? 4000 uf/amp was for around %15 ripple. 5000? 10,000? [ 12-13-2001: Message edited by: resago ]

12-13-2001, 11:26 AM	#50
Kevin Slacking more than your weird uncle Join Date: Nov 2000 Location: San Diego, CA (UCSD) / Los Angeles, CA (home) Posts: 1,605	Woah guys... this topic is GETTING HUGE! Mind if I lock it and start a new continuation thread? LMK... __________________ I used to throw hot coffee all over the ass of the horse there, then whip him while he was kickin' at me. Those f***in things are crazy.

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