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General Purpose LM317 Power Supply

MarioMaster

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Jul 27, 2007
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I decided to make a general purpose power supply for doing experiments or powering things with unusual voltage requirements. Using four LM317 regulators the supply can handle around 20-30 watts fairly easily although cooling is required as the LM317 chips are linear and generate a lot of waste heat. You can build one yourself with some fairly basic electrical knowledge.

1. Power switch - generic SPST toggle
2. Transformer - 120vac to 24vac at 2000ma, came from an electric scooter charger (higher ma rating the more power output)
3. Bridge rectifier - should be able to handle at least the output current of the transformer
4. Primary capacitors - more capacitance is better, cap value 1360uf, these are before regulators
5. Secondary capacitors - more capacitance is better, cap value 3300uf, after regulators
6. LM317 regulators - wired in parallel, add more for more output current
7. Output pot (R2) - 10kohm variable resistor (280ohm fixed resistor for R1)
Always be aware of maximum voltage ratings for components.

This supply will output 3-35vdc at several amps, good enough for powering misc. projects. I can draw up the schematic or provide more information via PM if desired.

-MM
 

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chronos

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Oct 18, 2007
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That looks like a neat circuit!
Have you thought about using LM338 for more amps?
 




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