Many time we do have old SMPS of no use to the computers. Those SMPS can be modified as bench-top power supply system providing -12,+12,+5,+3.3 volts. I have used one to power my all arduino based home automation modules and the Raspberry Pi. Here i am going to post how to mod an old SMPS .
You just need following components along with some basic tools
1.Screw Terminals.
2.Switch (On/Off).
3.10Watt Resistive load (May be 5K or 10K i have used 4.7K working fine)
