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Variable DC Power Supply for <$15

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
stewie00563 years ago
correct me if i am wrong but in the schematic you drawn the pot is just going to be a 5k resistor because you didnt attach the wiper to anything.

would you care to explain that for me?


one more thing. would a tl780-05c voltage regulator work?
I'm pretty sure that's just a standard symbol for variable resistor.
In comparison to some other similar instructables, I'd say the wiper terminal just needs to be connected to ground (ie. connect the wiper terminal to the bottom (in terms of the circuit diagram) terminal of the 5k variable resistor.
How do you know what capacitors and resistors to use?
hitachi83 years ago
how much power can i draw from this little thing ? what if i put a big heatsink on the transistor ?
I dont know much about this , but is a LM317t good enough ? What is the difference ?
It will work.
neardood5 years ago
what schematics?
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