ATX kludge

I will be visiting Fry's electronics or Radio Shack on Tuesday. Need to make a list of parts to use an old ATX power supply for 12V cigarette lighter projects.

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I'm copying this guy.

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But am going to put the switch, resistor, and lighter plug on the ATX 20-pin extension cable so I can switch out power supplies when I blow one up. Good plan?

Reply to
Stumpy
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"Stumpy" wrote in news:8oednefEW5GkYgnOnZ2dnUVZ snipped-for-privacy@earthlink.com:

You probably haven't got enough current carrying capability on a single pin of the ATX connector, so it is likely to burn up the connector if you run a high current load for long at the lighter socket . I'd want to use at least three of the old style hard drive power connectors in parallel to feed the socket.

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Reply to
Ian Malcolm

OK. The P.S. is rated at 12 amps on the +12v and the fuse on a similar cigarette lighter is 8Amp, 250V

The IDE HDD power connectors do look beefier, I'll try one by itself first.

Reply to
Stumpy

One by itself still means one single wire for +12V, no better than the ATX. Actually worse, since you only have 2 GND wires going to a HDD connector.

"At least 3" was a much better idea. Better still, use the ATX one as well and connect all the GNDs together. That way you won't get a voltage drop with a high current capacity to Earth Ground in your circuit. These can mess up instrumentation (think scope probe grounds) and other connected circuits in unpredictable and unpleasant ways.

Regards Dimitrij

Reply to
Dimitrij Klingbeil

I was going to use the connector for ease of swapping out power supplies. If I connect all the yellows and all the blacks together it's a one trick pony. I am assuming that my cheap, old power supplies are single rail and that the wires I see can handle up to 12 amps. If it fails, I certainly would tie them all together.

Reply to
Stumpy

Smoking will kill you. Bad plan.

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Reply to
John Larkin

I'll add a few Molex 8981 male pin, female connectors to my list and can still do a modular swap.

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Maybe they will have the Molex end of this cable sitting in a bin.

Reply to
Stumpy

Better plan might include several 12V sockets, with different resettable circuit breakers, for current limits other than all-the-power-available. There's other things than the power supply that might blow up.

Reply to
whit3rd

Right. Can't even get to that point. Somebody raided my storage closet, or cleaned it up. Only have 2 P.S. left. The Hopely (from a windows 95 box) made in ShenZhen just lays there. The Bestec which does have two 12v rails did some smoking on power-up. It gives a momentary pulse of 12v, then shuts off. I added a second 10ohm resistor to the +5v in case the sensing circuit is just cranky - no change.

I only spent $12.27 +tax but am unwilling to risk any of the installed P.S. Guess I have to wait until one of my Windows XP motherboards fails to try this again.

Reply to
Stumpy

Here's another option:

Reply to
whit3rd

Only 4 Amps might not light a stogie. It is nice and compact though, less expensive than my parts.

Reply to
Stumpy

Maybe a small lead-acid, gel-cell battery? Obviously not cheap, but... Keep it trickle charged from a 12V line through a resistor. It's possible NiMH batteries could supply 8 amps, you'll have to look it up. Certainly the ones from RC cars and planes should. Since this is a case where you need large currents for a small period, a battery like this might work.

Maybe even a stupidly-large capacitor, but not sure they'd have the energy capacity.

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Reply to
greenaum

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