[dorkbotpdx-blabber] 12 volt 20 amp power supply to drive a couple of pumps

Eric Garner garnere at gmail.com
Mon Mar 16 00:53:15 EDT 2009


LM3150 (http://www.national.com/pf/LM/LM3150.html) is a nice part in
concert with some passives and two FETs. if you're just driving 12v
motors, cheap battery chargers from harbor freight work a treat (at
minimum they make great,cheap "donor" transformers).

On Sun, Mar 15, 2009 at 7:50 PM, Dem Chi <dementedchihuahua at gmail.com> wrote:
> Yes, the input source is the AC line. I'm trying to keep the component count
> low. I need a 24Volt line at 0.4A. A 12V line at 20A and a 10V line for the
> arduino. I really didn't want to have a bunch of transformers sitting around
> in there if I could help it. The PC power supply idea is a good one. I guess
> I could use a step-up transformer to get my 24Volt line off of that...hmm.
> Besides, the transformers aren't all that cheap by themselves.
>
> I suppose it is a bit of power I'm trying to dissipate...bleh.
>
> Thanks for your response.
>
> On Sun, Mar 15, 2009 at 7:42 PM, John Luciani <jluciani at gmail.com> wrote:
>>
>> The problem is you need to drop too much voltage across your regulator.
>> You
>> will need to dissipate 240W (12V * 20A). You could parallel devices with
>> diodes but it is still a lot of heat (just spread out a little more).
>>
>> You either need to get a transformer with a lower voltage output or use
>> a DC-DC converter.
>>
>> Is the input power source the AC line (120VAC)? If it is the cheapest way
>> to get
>> 12V @ 20A would be a PC power supply.
>>
>> (* jcl *)
>>
>> On Sun, Mar 15, 2009 at 10:23 PM, Dem Chi <dementedchihuahua at gmail.com>
>> wrote:
>> >
>> > Hi all,
>> >
>> > I'm making a power supply to drive two 12V 8amp DC motors. They are for
>> > a
>> > filtration box. They will be used both intermittently and sometimes for
>> > long
>> > durations. I've got a bridge rectifier from mouser rated for what the
>> > transformer that I have outputs (621-GBJ20005-F). I'm getting a 24V line
>> > at
>> > ~20 amps. I need to take this down to a 12 volt line and current limit
>> > it so
>> > that I don't burn up my pumps. I am also taking off a 10 volt line for
>> > an
>> > Arduino but this is less important at this point.
>> >
>> > My problem is that voltage regulators that I've found--not many--that
>> > can
>> > take 24 volts and output 12 volts with 20 amps are expensive. Can anyone
>> > suggest a circuit or IC or anything that will take the 24 volts I'm
>> > giving
>> > it and output a 12 volt 20 amp line?
>> >
>> > Priorities are cost and ease of construction. No surface mount parts or
>> > anything like that.
>> >
>> > Any help is good help! Thanks
>> > Stan
>> > --
>> > http://www.urbansurvivalists.com/
>> >
>> > _______________________________________________
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>> >
>>
>>
>>
>> --
>>
>> You can't create open hardware with closed EDA tools.
>>
>> http://www.luciani.org
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>
>
> --
> http://www.urbansurvivalists.com/
>
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-- 
--Eric
_________________________________________
Eric Garner


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