# I need a 20 amp 15 volt power supply or a variable power supply that provides 20 amps and 0-30 volts

#### Ian Hickler

Joined Jul 14, 2017
14
Hi i am a beginner who is trying to figure out if i can get 20 amps at 15 volts. I need this to power a peltier or a thermoelectric cooler that requires 15 amps at 15.4 volts. I was wondering if there is an easy way to make a circuit that is good? I know how to solder pretty well and i have a fine tip though i have never soldered anything to a pcb before... Also would this be an easy task to do? I have two spare PC power supply but they only provide 12 volts at 17 amps not what i am looking for. Please respond as fast as possible thanks, Ian

P.S I am 13 so sorry for the lack of grammer. I dont have a copious amount of words to use....

#### dl324

Joined Mar 30, 2015
15,474
Welcome to AAC!

20A power supplies aren't easy to build. High current transformers are bulky and expensive. Transformerless power supplies are a forbidden topic. They're too dangerous for inexperienced people.

I'd suggest checking into hacking a computer power supply. They supply a lot of current, but I don't know off hand if the 12V supply can be hacked to provide 15V; or if it can provide 20A.

Regarding grammar. Just use what you've been taught. Organize your thoughts into paragraphs, use run on sentences or fragments for effect (i.e. rarely), spell out words (i.e. don't use "text speak", many on this forum don't approve of that form of communication), use proper capitalization and punctuation. You don't need to use a lot of words or "big" words; just make what you write intelligible.

#### Ian Hickler

Joined Jul 14, 2017
14
Hey thanks guys for telling me all the advice. As a 13 year old I don't have enough money for a 60$part so how would I have a power supply to get 15 rather than 12 volts... Ian Thread Starter #### Ian Hickler Joined Jul 14, 2017 14 Welcome to AAC! 20A power supplies aren't easy to build. High current transformers are bulky and expensive. Transformerless power supplies are a forbidden topic. They're too dangerous for inexperienced people. I'd suggest checking into hacking a computer power supply. They supply a lot of current, but I don't know off hand if the 12V supply can be hacked to provide 15V; or if it can provide 20A. Regarding grammar. Just use what you've been taught. Organize your thoughts into paragraphs, use run on sentences or fragments for effect (i.e. rarely), spell out words (i.e. don't use "text speak", many on this forum don't approve of that form of communication), use proper capitalization and punctuation. You don't need to use a lot of words or "big" words; just make what you write intelligible. Thanks for the response but I don't know how to hack a power supply do you know how or can you teach me??? Thread Starter #### Ian Hickler Joined Jul 14, 2017 14 First shot at a shopping trip reveals answers in the$2000 range.
http://www.mouser.com/Power/Power-S...lies/_/N-dqmv7?P=1yx5k7vZ1yepm8r&Ns=Pricing|0

If I recall correctly, a Peltier is a "stupid" load. It allows current based on voltage and is not concerned much about the cleanliness of the DC.
How do you feel about $60? http://www.mouser.com/Power/Power-S...=axgkhZgjdhnxZ1yxt7f0Z1yuqqmeSGT&Ns=Pricing|0 Hey thanks for the advice but 60$ is way out of my budget do you have any other ideas?

#### crutschow

Joined Mar 14, 2008
31,141
Your grammar is better than some of the regular contributors to this forum.
And your writing is certainly much easier to understand than some who use way too many "copious amount of words".

#### recklessrog

Joined May 23, 2013
985
AHEM!!! Computer power supplies are usually "transformerless" and are particularly dangerous for inexperienced persons to try and modify!
There is a very real risk of severe shock or death if you don't have the right equipment and knowledge to work on them.
Please don't suggest that as a viable option!!

#### be80be

Joined Jul 5, 2008
2,070
You sure you need one that's 15 amps these supplies for big coolers are only around 5 amps.
do you have a link for the thermoelectric cooler.

#### MrChips

Joined Oct 2, 2009
27,709
What is the wattage rating of the TEC? Are you certain it is 230W?
What is the model number?

#### Ian Hickler

Joined Jul 14, 2017
14
Your grammar is better than some of the regular contributors to this forum.
And your writing is certainly much easier to understand than some who use way too many "copious amount of words".
Lol thanks i didnt think it was really good

#### Ian Hickler

Joined Jul 14, 2017
14
Hey I still can't figure out a viable option for powering a 15amp 15 volts peltier the nearest thing i have to that is a power supply at 12 volts 17 amp... So if anyone has a cheap option to get that kind of voltage that would be nice. Would this have to require a variable power supply?

#### dl324

Joined Mar 30, 2015
15,474
Hey I still can't figure out a viable option for powering a 15amp 15 volts peltier the nearest thing i have to that is a power supply at 12 volts 17 amp... Would this have to require a variable power supply?
Use your surplus PC power supply. If you want to vary voltage to tweak performance, you can add a variable voltage regulator to the output of the 12V rail; assuming you don't want more than about 9V. You could use an LDO regulator to get more, but you'll still need an external pass transistor to get high current (more than 1A or so).

8V@6A will give a delta T of 50C.

#### Ian Hickler

Joined Jul 14, 2017
14

#### panic mode

Joined Oct 10, 2011
2,365
you can use PC power supply... plenty of models will do 20A or more. this is cheapest way to get high current PSU. usually they are discarded as people periodically replace entire computers.

few things to note:
- be safe and understand the risks.
- check rated voltage of capacitors in the DC output.
- whatever PSU you have it will have controller chip, find the datasheet for it. this will allow you to adjust output voltage.
- if you are adding pot to adjust the output voltage, make sure to size components carefully to limit the output voltage so you don't accidentally crank it up and blow up your PSU and whatever is powered by it. i was modifying couple of them and they easily performed up to 20V.
- if it is ATX power supply, you may want to permanently connect green wire to 0VDC (black)
- some PSU may need minimum load to work properly

#### be80be

Joined Jul 5, 2008
2,070
I think you better think a little harder here first that doesn't need 15.4 volts that's the maximum voltage.
Next you don't want no 15 amps to start playing with this thing because that also is a maximum rating.
And this one
You can always run these at lower voltages for higher efficiency - as the current decreases, the coefficient of performance increases. At 12 volts the ΔT is almost 60°C. As you decrease the voltage and current draw, ΔT will decrease, but even at 1 volt there is a noticeable temperature difference, accompanied by the most efficient heat pumping you will find for this price.
You put 15 amps at 15.4 volts I bet you'll be buying a new one. To use this you need to have big heatsink and good fan and Vacuum testing At the max rating.
I'd start way lower and see how it goes.
I really like this from the datasheet kind of means some of the stuff maybe wrong and
they just put it out to give a starting point.
All specifications subject to change without notice
That means when you burnout your 2 dollar Thermoelectric Module don't call them wanting money back.

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#### cmartinez

Joined Jan 17, 2007
7,881
I think you better think a little harder here first that doesn't need 15.4 volts that's the maximum voltage.
Next you don't want no 15 amps to start playing with this thing because that also is a maximum rating.
And this one
You put 15 amps at 15.4 volts I bet you'll be buying a new one. To use this you need to have big heatsink and good fan and Vacuum testing.
I'd start way lower and see how it goes.
I really like this from the datasheet kind of means some of the stuff maybe wrong and
they just put it out to give a starting point.
I agree, it was most probably designed to be run at 12V, allowing for a security factor up to 15V