I am looking to build a power supply for a project. It will be running a computer and some other devices connected to it.<p>so I am thinking a +-5v, +-12 volt will do everything I need. I would like to build it between 3 to 6 amps. <p>is this feasible to do with a pack of lithium poly's stacked to create a 14.4 battery?<p>I know there is issues with lithium poly's(fire and charging), but weight is an issue. <p>also how clean do I need to make the DC, since it is running micro devices?<p>I have looked at using lm317's, but I am also interested in switching power supplies.(due to heat and a cleaner signal)<p>I would like to here pro's and con's about the two types above. <p>any ideas and pointers are greatly appreciated...<p>
TIA
James
voltage regulator circuit
Re: voltage regulator circuit
317 will bring you night mare at this application. You must install a large heat sink to aviod it from burning at 3-5A current.<p>I strongly suggest you using DC-DC modules with built-in stablized circuit. linear regulator is cheaper, and less EMI. but it generate terrible heat in high current applications. DC-DC is expensive, but has higher effeciency and generate less heat. <p>'clean' doesn't affect the motherboard greatly, there're many filter circuits on the board.
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Re: voltage regulator circuit
What's wrong with using an old PC power supply.<p>
~ ;o)
~ ;o)
Re: voltage regulator circuit
The 317 (from national, anyway) has an absolute max current rating 3.4 A but, as pointed out, that is with a huge heat sink. I wouldn't design a circuit that runs up anywhere close to the spec'd limits. The 317 spec's go to h*ll when the temperature gets pretty high. You can do a number of things to get higher current but it gets more complex. See the national datasheet.<p>If your goal is to learn by building a power supply, then go for it but if your goal is to power some circuits, I'd suggest an off the shelf power supply. The computer power supply suggestion is a good one.
Re: voltage regulator circuit
using a pc power supply is a great idea. But weight is an issue. This stuff is going in a R/C airplane. So, weight and heat is an issue.<p>Thanks for the ideas so far...<p>Keep em comming please<p>TIA
James
James
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Re: voltage regulator circuit
A computer that needs 3 to 5 Amps is a big computer to put in an R/C plane, must be a BIG R/C plane. And batteries too! Even with lithium, a 5 to 10 AmpHour stack for primary power is going to be heavy.<p>IMO you need a DC to DC module. 12V (nominal) in, +-5 +12 out. It would be hard to build one lighter and smaller.<p>Just an idea - with microcontroller (PIC, Stamp, Zilog, etc) and RF MODEM on board, you can just use +5 at under an Amp. Weight goes WAY DOWN. Do the number crunching in the ground.<p>Cheers,<p>[ May 26, 2005: Message edited by: Dale Y ]</p>
Dale Y
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Re: voltage regulator circuit
That brings up an interesting question: has anyone ever connected a generator/alternator to a small R/C gas engine? Think of it: an easily transported source of power without the limitations of batteries: just use a larger gas tank.
Re: voltage regulator circuit
Have you considered solar cells on the wings? Not as primary power, of course, but to keep your batteries topped off, and to a minimum their weight. You'll want the highest watt/weight ratio.
WA2RBA
Re: voltage regulator circuit
good Idea about the solar cells
and yes they do have generators that can be placed on the engine
and yes they do have generators that can be placed on the engine
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