Author Options:

How do you test a dc voltage regulator? Answered

I have a dc volt regulator that reduces the voltage to around 12 volts. How can I tell if it is good or not?


To test a DC voltage regulator, just hook it up to a circuit. Input sufficient voltage into its input and then take a multimeter, placed on the DC voltage meter, and measure to see that the output voltage is the rated voltage that the regulator is meant to supply. So the only test equipment is a multimeter.
Check the following page out, http://www.learningaboutelectronics.com/Articles/How-to-test-a-voltage-regulator

It has explains this in more depth and in pictures.


8 years ago

Wow, looks a little crusty.  What happened to it?

You should attach a DC voltage at it's INPUT that is higher than the 12 volts expected output voltage.  The input must not exceed the LIMITS of the device.  Less than 25 volts is probably ok.   Connect the GROUND terminal also.  Then look to see if the OUTPUT is 12 volts within the limits of 11.9 to 12.1 aprox.  ALSO you should look at the output with an oscilloscope to be sure the device does not OSCILLATE.  This would appear as a ripple in your output.  The output should be SMOOTH DC with only a few millivolts of ripple.  The device should be BOLTED to a heatsink for this test so it does not overheat and die during testing.  SOME regulators are NEGATIVE output regulators.  They have a MINUS output, so be sure to connect the input properly in that case.  Usually a normal regulator will have a serial number starting with the number 78  such as ua7812.  That would be a POSITIVE 12 volt regulator.  If it has the number 79... then it is a NEGATIVE output regulator.... ua7912 is negative output.

With a voltmeter.  Hook it up to a source, and measure the output voltage.

Um, duh?

Put it in a proper circuit.  If it works it's good.  If it doesn't work then it's not good.