[Noisebridge-discuss] N00b question - changing power supplyvoltage

jim jim at well.com
Fri Jul 2 03:07:17 UTC 2010



   maybe you could put two peltier junctions in series? 

   as to parallel rectifiers, i'd like to know if that 
works. i wouldn't do it except as an experiment--every 
semiconductor junction is a little bit different from 
every other. the junctions in one rectifier may or may 
not be nearly identical, depending on the manufacturing 
process, but it's a pret' near sure bet the junctions 
in a second rectifier will be different from those in 
the first. therefore there's a chance that one rectifier 
will be "favored" and pass more current, possibly lots 
more current. one way to mitigate that possiblity is to 
put a very low value, relatively high wattage, power 
resistors in series with each rectifier (identical 
values, of course, and test to be sure their resistance 
really is just about exactly the same): 0.5 ohms at 
10 Watts should work. 




On Thu, 2010-07-01 at 19:29 -0700, Lee Sonko wrote:
> Since a peltier junction is a big hunk of metal (and not a
> semiconductor), and it won't draw variable amounts of power, I guess
> you don't need any capacitors to smooth out the power.
> 
>  
> 
> Your 24volt 4.5 amp power supply will only be able to supply 12 volts
> 4.5 amps with a voltage regulator. It won't be able to supply more
> amperage.  Also note the voltage regulator I pointed to isn't rated
> for 4.5 amps. The regulator is liable to overheat. I -think- it's ok
> to put 2 voltage regulators in parallel to up the amperage ability but
> I don't know for sure. 
> 
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> 
> Have fun freezing/burning the castle!
> 
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>                                    
> ______________________________________________________________________
> From:noisebridge-discuss-bounces at lists.noisebridge.net
> [mailto:noisebridge-discuss-bounces at lists.noisebridge.net] On Behalf
> Of Sean Cusack
> Sent: Thursday, July 01, 2010 6:03 PM
> To: Ryan Castellucci
> Cc: <noisebridge-discuss at lists.noisebridge.net>
> Subject: Re: [Noisebridge-discuss] N00b question - changing power
> supplyvoltage
> 
> 
>  
> 
> Awesome - thanks guys!
> 
> I'm going to try to use this guy to power a peltier cooler (I've got a
> sweet idea here depending on how well I can get this doo-hickey to
> work). It takes 12V at up to 9A, but from the reading I've been doing,
> it looks like you want to stay away from the top value of amperage
> anyways. I'll give it a spin with just the 4.5A first to see how it
> works.
> 
> Based on what I'm seeing below, if I use 2 voltage regulators in
> parallel, it looks like that should handle the current without a
> problem. I can totally drop in a cap after the fact to smooth out the
> current. Ryan - I'm considering doing an ATX PSU mod too...I've got an
> extra one laying around.
> 
> Sean
> 
> On Thu, Jul 1, 2010 at 5:05 PM, Ryan Castellucci
> <ryan.castellucci at gmail.com> wrote:
> 
> How much current are you drawing?  TBH, you should really just go to
> weird stuff and pick one up for a few dollars.  Another option would
> be converting an ATX power supply to a bench supply.
> 
> 
> On Thu, Jul 1, 2010 at 1:57 PM, Sean Cusack <sean.p.cusack at gmail.com>
> wrote:
> > Hey kids -
> >
> > So, I've got a relatively simple dilemma that I sure pops up all the
> time
> > for those of you that are way better at electronics than me. I've
> got a
> > power supply providing a fixed 24V @ 4.5A, but I only want to use
> 12V of
> > that for my circuit. I originally thought I could lower the voltage
> using a
> > potentiometer, but because the power is so high, they all cost some
> serious
> > bank. Is there another (not necessarily analog) solution to changing
> voltage
> > and/or amperage through a circuit that is cheap to build?
> >
> > Sorry if this one is likely obvious - but everyone can blame Mitch
> for
> > getting me way to into electronics for my own good :).
> >
> > Sean
> >
> 
> 
> > _______________________________________________
> > Noisebridge-discuss mailing list
> > Noisebridge-discuss at lists.noisebridge.net
> > https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss
> >
> >
> 
> 
> 
> 
> 
> --
> Ryan Castellucci http://ryanc.org/
> 
> 
>  
> 
> 
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