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Topic: LM317T Voltage Regulator problem (better photos) (Read 1 time) previous topic - next topic

majenko

Make sure that the LM317T is properly wired.  I suggest you remove all other components from the breadboard to give you room to work.

Ensure that you have the 360? between pins 1+2.
Ensure that you have the 519? between pin 1 and ground.
Ensure that you have the power input at a minimum of about 5V and connected to pin 3 and ground.
Ensure you take the output from pin 2 and ground.
[/b]Most importantly, ensure that all the grounds are connected.[/b]
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RobertEagle

#6
Aug 24, 2012, 01:24 pm Last Edit: Aug 24, 2012, 05:23 pm by RobertEagle Reason: 1
Yep. I've finished the checking procedure. All the components are staying at the proper position and are connected to each other.
All I get when I measure with the multimeter is the voltage input minus the dropout voltage.
I evenly switched the regulator with another one of the same model.

EDIT: I found what was the ,,problem". As long as the resistors are leveled with few ohms the output voltage will vary very much, but when there are bigger resistors(like 100k, 800k) there is almost no problem.

Lavan

Ok.  What is the voltage between PIN3 of LM317T and GND?  Replace the R2 with a wire and check the output voltage at PIN2 and GND, it should be around 1.2V.  If you are not seeing 1.2V, then check the wiring or LM317T.




RobertEagle

It's 5V. Yeah. It gives me like you said.
It's because of the resistors. As I said, the bigger they are, the smaller the error.

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