Computer Power Supply modification 12v

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Dragonfly
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Wed Feb 16, 2011 6:29 pm

I have been using a couple of old computer Power supplys to power my spare CB radios.some work great some give a couple of pounds of interference but if you have some laid about them give them a try.


This computer Supply pictured is rated at 24amps on the 12v out.
Image


Bridge the Brown wire to a Black on the older power Supplys . On the newer Power supplys bridge the green wire to a black.
This loop takes the place of the PC start Button.
Image


The Molex Plug will now give you 12 volts DC at the Yellow and Black connections and 5 volts DC at the Red and Black connections .
Image

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Eviltwin
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Wed Feb 16, 2011 11:01 pm

Nice recycling, and plenty of free power supplies floating round as old PC's get thrown out.
I'm no expert, please take anything i say with a tablespoon of salt!

Dragonfly
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Tue Feb 22, 2011 9:44 pm

The PC power Supplys only give 12volts so you will find that your radio is only showing around 3 to 3.5 wats on transmit , as against using a propper power supply 13.8 volts which will give you 4 to 4.5 wats on transmit, but it will get you started until u can afford a propper supply.

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Andy Nazel
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Thu Feb 24, 2011 1:37 am

Sorry Dragonfly but I must beg to differ.As I understand it,its the amount of current the PSU delivers that makes the difference not the voltage.Anyway I can't see a 1.8 volt variance creating such a reduction in a radios output power.Also,I have checked the specs.for my Maycom EM27 and Intek M550 and the input voltage stated for both radios is 13.2 volts and the Intek has a 15%+- tolerance for the input voltage so it would be ok on 12V as long as it can pull the 2amps it needs to work.(But what do I know :? I drive for the council!!! :D :lol: .)

Dragonfly
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Sat Feb 26, 2011 5:56 pm

My comparison was done with a Fidelity 1000 which i picked up for £3 at a car boot on sunday gone ,though i have to admit that i didnot use the same antenna for both tests so the variation in output may be much smaller.

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stampman
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Thu Nov 21, 2013 8:08 am

cbs are designed to be most efficient at 13.9 volts as this is the standard voltage of a car when running they were made to run at this voltage because the american waggons ran at 12 volt battery voltage so you need 13.9v to charge them running at a lower voltage they do not perform as well


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RustySkull
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Mon Jan 13, 2014 7:16 am

stampman wrote:cbs are designed to be most efficient at 13.9 volts as this is the standard voltage of a car when running they were made to run at this voltage because the american waggons ran at 12 volt battery voltage so you need 13.9v to charge them running at a lower voltage they do not perform as well


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