Computer PS to a Bench-top PS

Buying a Raspberry Pi, I needed a USB power supply.  So, I am converting a old computer switching power supply to a bench top power supply that I can use to power my small projects.

How to Convert a

Computer Power Supply

to a

Bench-top Power Supply

by

Johnny McCown

30 December 2012

Introduction:

Recently I received a Raspberry Pi computer from a friend of mine. It uses an USB connector for its 5Vdc input power. I have USB cables laying around, but the only power supplies I have are those that were provided by my smart phone and tablet. Recalling that another friend of mine Dell-Ray had told me in the past that he heard of a man using a Computer PS as a Bench-top PS, I thought I would do the same, so I looked up this idea on Youtube and Google.

Start of Project:

My first task was to remove the circuit board out of the Computer PS. I disconnected the input AC connector, 110/220 Vac switch, and power switch. Once I had the board removed, I then unsoldered the output voltage lines that supply GND, 12Vdc, -12Vdc, 5Vdc, and 3.3Vdc. Also, I disconnected the two 12Vdc cooling fans. As I am looking over the circuit card I notice the parts that are used to filter out noise from the output power lines and also the parts that prevent noise from entering the input AC mains are not included. It would be helpful to solder in these components to filter the power.

Possible Improvements:

Dennis – recommended that I use one of the displays that I got at the German Ham Fest to give the PS a voltage and amp readout of the three different outputs. Also, he reminded me to fuse each individual output so that if I have a fault with one of my projects it will not effect the other outputs or harm the power supply.

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