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Homemade power supply problems Answered

i am trying to build a variable power supply using a LM317 variable voltage regulator. When connected to no load, i can get a sweep from 1 volt to 15 volts. but when a load (small pager motor, laser diode) is connected, i can only get up to 4 volts, and about 12 milliamps of current. Help!


Show your working - like, what circuit do you think you've used. And you can't get more OUT than you put IN, so what have you used for the input ?

sorry for the VERY late answer: i am using a laptop power supply for the input. 24 volts at 3.5 amps. i got the LM317 at radioShack, and used the schematis on the back of the package. ;) go to: https://www.instructables.com/files/deriv/F46/KH63/FABDYTP5/F46KH63FABDYTP5.MEDIUM.jpg for the schematic.

Have you wired the package properly ? Stranger things have been known to happen. What happens to the input volts when the load is connected ?


i am sure the package is wired properly. If it wasn't, would it still create a voltage sweep?

Sometimes they do. Possibly you have a bad ground connection.
What did you do with the tab of the 317 ? It is Vout - you mustn't connect it to ground !!


what you read is dependent upon load, what's the power supply?