Tag Archives: variable voltage

Variable Voltage Power Supply using a LM317

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A classic afternoon project. I was in need of a variable voltage and didn’t have a proper lab power supply available. But I did have a solid 12 volts from an old computer PSU. So I built myself this little thing.

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It’s really nothing more than a LM317 in a TO220 package with a pot, two capacitors and banana jacks. It measures about 65x55mm and has rubber feet so it sits nicely on the bench. All the parts I found laying around here. The little heat sink can handle 5 to 10 watts without getting overly hot.

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Over a short period of time you can burn quite a bit more so you can draw up to 1.5 Amps (the LM317’s internal current limit) from anywhere between 1.25 and 10 volts when connecting it to a 12V supply.

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