How to Convert SMPS to Bench Power supply cum charger



Don’t throw away the SMPS power supply when the Computer damges. SMPS is a high current device that gives different regulated voltages from the output wires. It has numerous wires to give different voltages . So you can make a good Multi voltage power supply for the Projects or use as battery charger for different types of batteries. It has total isolation from Mains and output is safe DC.


First you have to separate and group the wires based on the colour. Then join the wires of the same colour.
The output is as follows.
1. A single Blue wire – Minus 12 V
2. All Yellow wires – + 12 V
3. Join the single Brown wire + all Orange wires – + 3.3 V
4. All Red wires – + 5 V
5. Violet wire – Connect a Red LED with 220 Ohms resistor between Violet wire and a Black wire – This LED indicates stand by state of SMPS
6. Green wire – Connect a switch between Green wire and a Black wire- It is the ON switch of SMPS
7. Connect a a Green LED with 220 ohms resistor between Red wire and a Black wire – It indicates Power ON status of SMPS
8. Connect a 5 Ohms 10 watts resistor between Red wire and Ground. This is the load resistor for the stable operation of SMPS.
9. All black wires – Ground.









In some SMPS, a White wire is present which is – 5 V. Cut it if you are not using it.
If you use Banana plugs to tap voltage, connect Blue, Yellow, Orange , and Red wires to 4 Banana plugs and connect all Black wires to a single Banana plug. If you use a Rotary switch, connect the different wires to the pins of switch and take the output from the common pin. So that, you can use only one output Flower plug for + and -. By turning the Rotary switch, you get the corresponding output voltage.

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