How can you tell if a transistor is NPN or PNP?

Using the method for publication of NPN from PNP. If you have a transistor but you do not know if it is NPN or PNP, then you can find out what is the use of Ohm-meter if you know which conductor of your meter is positive. … If you receive a read, then the transistor is PNP. Check by measuring from base to transmitter.

Attach the black probe to 1 of the transistor cables.

Touch the red probe for each of the other 2 pipes.

If the display shows a high resistance when each cable is touched, you found the base (and you have a good NPN transistor).

If the display shows 2 different readings for the other 2 conductors, set the black probe to another conductor and repeat the test.

Once you have fixed the black probe to each of the three conductors, if you do not get the same high resistance reading when you touch the other 2 red probe conductors, you have either a bad transistor or a PNP transistor.

Remove the black probe and fix the red probe to 1 cable.

Touch the black probe for each of the other 2 pipes.

  • If a high resistance appears on the display when each cable is reached, you found the base (and you have a good PNP transistor).
  • If the display shows 2 different readings for the other 2 leads, fix the red probe to another conductor and repeat the test.
  • After attaching the red probe to each of the 3 conductors, if you do not get the same high resistance reading when you touch the other two black probe leads, you have a bad PNP transistor.
Recent Updates