[Noisebridge-discuss] N00b question - changing power supply voltage

[Corey McGuire]

BTW, do not be tempted to stage them.  Staging them, one on top of the
other, works only if your second TEJ can cool the sum of the first TEJ AND
the original heat source.  So, if your heat source is 100 watts, and your
first TEJ is 120 watts, your second TEJ would need to move 220 watts of heat
readily.

Even if your heat source was 10 watts and your first TEJ was 120 watts, you
would still want your second TEJ to dissipate over 130watts.

Messy, messy stuff.  TEJ's are not efficient.  This is fine by themselves.
When you stage them, their inefficiencies become readily apparent as they
begin to compound.

May I ask what you intend to do with them?

On Mon, Jul 5, 2010 at 11:14 PM, Sean Cusack <sean.p.cusack at gmail.com>wrote:

> Cool - these particular dudes do say 15.6V max for some reason, but I have
> a hard time believing that I'm going to destroy the semiconductor by
> throwing more voltage at them anyways.
>
> I've got 7 of them, and really only need 2-3, so I'll try to smoke a couple
> :). Was going to do it today but got busy...with whiskey. Tomorrow should be
> it tho.
>
> Sean
>
> On Mon, Jul 5, 2010 at 8:08 PM, Corey McGuire <coreyfro at coreyfro.com>wrote:
>
>> If the power supply can deliver 24volts at 9amps, it would be no less
>> happy than if it was providing 12volts at 9amps with a few voltage
>> regulators.  Voltage regulators seem like the least ideal way to go.
>>
>> ADDITIONALLY, TEJ's that I've seen are designed, actually, for 18v.  This
>> seems to be the standard.  Just because they were marketed for a 12v power
>> system doesn't mean they can't be used for something more.  Find the source
>> of your TEJ's and read their papers.
>>
>> If you want to get crazy, so long as they don't get too hot, there is
>> really nothing preventing them from taking more voltage.  An "18v" TEJ can
>> probably take 24v...but I won't take responsibility if you smoke them ;-)
>>
>> The trick with TEJ's is that you need a TEJ that uses *AT LEAST* as much
>> power, in watts, as the heat you are trying to dissipate, in watts, and then
>> you need a slug of metal that can easily dissipate all that heat.  You
>> REALLY need to over design your cooling system.
>>
>> So, whatever you are doing, using two TEJ's in series will allow not just
>> for double the cooling power, but also double the surface area for heat
>> sinks.  This fact alone makes me side with the "run two in series" folks.
>>
>> On Thu, Jul 1, 2010 at 7:27 PM, Ryan Castellucci <
>> ryan.castellucci at gmail.com> wrote:
>>
>>> That would work, but the power supply may get unhappy (depending on
>>> the type, either very hot, or shut itself off) about having so much
>>> current drawn.
>>>
>>> On Thu, Jul 1, 2010 at 7:25 PM, Thor <himynameisthor at gmail.com> wrote:
>>> > Oh hey, what about just running two in series? Double the cooling
>>> without
>>> > any additional circuitry =)
>>> >
>>> > --
>>> > Heph
>>> >
>>> > On Jul 1, 2010 7:05 PM, "Ryan Castellucci" <ryan.castellucci at gmail.com
>>> >
>>> > wrote:
>>> >
>>> > At that much current, the voltage regulators are likely to *extremely*
>>> > hot.  You'll probably need a heat sink and fan to keep them from
>>> > melting.
>>> >
>>> > On Thu, Jul 1, 2010 at 6:03 PM, Sean Cusack <sean.p.cusack at gmail.com>
>>> wrote:
>>> >> Awesome - thanks guy...
>>> >
>>> > --
>>> >
>>> > Ryan Castellucci http://ryanc.org/
>>> >
>>> > _______________________________________________
>>> > Noisebridge-discuss mailing list
>>> > Noisebridge-discuss...
>>>
>>>
>>>
>>> --
>>> Ryan Castellucci http://ryanc.org/
>>> _______________________________________________
>>> Noisebridge-discuss mailing list
>>> Noisebridge-discuss at lists.noisebridge.net
>>> https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
>>>
>>
>>
>> _______________________________________________
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>>
>
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Success is a tasty spirit distilled from bitter failure
- Corey Sean McGuire
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