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A Variable DC Power Supply for Electronics Hobbyists 2010-07-13

A variable DC power supply is one of the most important tools for an electronics hobbyist. Most of the microcontroller based projects can be done with a fixed +5V supply but while testing various analog circuits you may require a varying voltage source. I have made one for myself using LM350 IC. The LM350 is an adjustable 3-terminal positive voltage regulator that can supply in excess of 3A over a 1.2V to 33V output range. They are exceptionally easy to use and require only 2 external resistors to set the output voltage. Here is a snapshot of my power supply unit.

It has a nice analog voltmeter to display the output voltage and a 5K potentiometer to vary the voltage. The circuit to control the output voltage is very simple, and is available in the datasheet on LM350 IC.

The Vin can be connected to an unregulated DC voltage obtained from a step-down transformer through bridge rectifier. I set the values of R1 and R2 so as to get variable DC voltage ranging from 1.25-18V. For more details of this project, visit here.

I hope you will like it.
- Raj
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