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PSU to run a CB Radio

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April 19, 2011 1:49:59 PM

A co-worker has a 12v automotive CB radio he wishes to use in the house.
With it's amplifier he will need around 150w. Dedicated AC to DC converters are enormously expensive.

I see no reason he could not use a computer PSU to do the job. Jump the green to black wire, hook up a fan to ensure load on the PSU, connect red to red, black to black plus a ground wire from the case of the radio to the PSU, and it should work.

I am grateful for any thoughts you have on this. Thanks!

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a c 665 ) Power supply
April 19, 2011 2:49:04 PM
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April 19, 2011 3:22:52 PM

Interesting. I had not thought of that - nor had he I am sure. :)  Thanks rolli59!

Still, I am hoping for a positive response that my above idea is practical.
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a b ) Power supply
April 19, 2011 5:11:55 PM

If you draw power from the 4-pin Molex output connector of a PSU, here is the color coding:

http://en.wikipedia.org/wiki/Molex

Note that Ground is Black, Yellow is +12 VDC, and Red is +5 VDC - not needed by your app (unless a small load is needed on the +5 VDC line to operate in this non-standard configuration).

A Molex 4-pin often is not wired very heavily - after all, its intended use is for HDD's etc. that use less than 1 amp each. Your friend's system will need more like 13 to 15 amps available. But if you go to the 20-pin output that is supposed to plug into a mobo, the pinout diagram is here:

http://pinouts.ru/Power/atxpower_pinout.shtml

Again, Black is Ground, Yellow is +12 VDC., and it is designed for higher currents.

In buying a PSU, remember that not all its output Watts are on the +12 VDC line. For example, I checked a cheap ($25) 180W PSU and its +12VDC line can output only 10A - net enough for your friend's 150W application. Some cheap 250W units with SINGLE 12 VDC rails put out 13A to 16A max, depending on the unit, just barely enough. A DUAL-rail +12VDC PSU probably is NOT what you want because its +12VDC ouput is split, and you may not get enough from one rail to meet your 13 to 15 A requirement.
April 19, 2011 5:55:48 PM

I bookmarked this page and will ask my friend for exact numbers and get back.
[:henry chinaski:8] I have never looked at pinouts. Dummy me!!
Glad you mentioned it.
I would have made a mistake.
April 26, 2011 1:35:06 AM

Talked to my coworker today, his wife made the final decision....! :) 

She seems to feel the converter recommended by rolli59 would pose less of a fire hazard (?) to the family.
"When mama ain't happy, ain't no one gonna be happy"

Thanks guys!
April 26, 2011 1:35:22 AM

Best answer selected by Noworldorder.
!