Introduction: Variable DC Power Supply for <$15
Step 1: The Parts
- LM317 Voltage Regulator ($0.50)
- 0.1 uf Mylar Cap (~$0.10)
- 1 Axial Electrolytic Cap (~$0.20)
- 220 Ohm Resistor (~$0.05)
- 5K Potentiometer ($1.00)
- Cheap Voltmeter ($7.95)
- Enclosure ($1.65)
- Power Supply ($2.85)
Not bad for a homemade variable DC power supply!
Step 2: The Variable Voltage Regulator.
Start by making the variable voltage regulator. Refer to the schematics below.
Step 3: Adding the Digital Readout
Adding the digital readout is really simple! Just open up your multimeter and solder your output to the test leads. Add a switch to the battery. And that's it! You're done :D
Step 4: You're Done
Test it and have fun! Put it in an awesome enclosure like I did to impress your friends :)