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Everything Else » Why is my voltage regulator not working

December 25, 2009
by 787pilot
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My voltage regulator gets hot when I put current in it and does not out put any voltage please tell me ASAP

December 25, 2009
by mongo
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UH OH!

Could be something simple like mis-wired... But it sounds like it may have gotten cooked.

Check the connections... Looking at the regulator from the face, the three terminals are V+ in, Ground (which is V- in and out) and the last one is V+ out. If it's backwards, it can indeed get hot.

December 25, 2009
by 787pilot
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It is in right and it is wired right but it wont out put voltage

December 25, 2009
by BobaMosfet
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What are you connecting to it? Your 9-volt battery? Do you get any reading from a volt meter? Did you connect your power-source backwards?

December 25, 2009
by mongo
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One more possibility...

Is the output shorted to ground? Might want to double-check the wiring.

December 25, 2009
by 787pilot
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yes 9-volt and I have cheaked it over and over and the battery is in right

December 26, 2009
by mongo
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OK, Try separating the regulator from the rest of the circuit. With nothing connected to the output pin, you should read 5 volts. If it does not read 5V, it's toast. Fortunately, these are inexpensive parts and can be easily picked up at nearly every electronics outlet.

7805 is a common number. I use the LM340T5 variation but it's all pretty much the same.

December 28, 2009
by hevans
(NerdKits Staff)

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Hi 787pilot,

The most common cause of this issue is a misplaced wire somewhere. Remember that a short anywhere on your circuit will cause the voltage regulator to overheat, so make sure you double check all of your wiring, particularly the power connections to the MCU which are easy to mix up. If you can, post up some pictures of your setup here on the forums, I'm sure one of us will be able to spot the issue. Let us know if you find the the problem.

Humberto

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