Connect with us

how to know the transistor is npn or pnp

Discussion in 'Electronic Basics' started by newone, Dec 21, 2005.

Scroll to continue with content
  1. newone

    newone Guest

    how to know the transistor is npn or pn

    please whith full detai
  2. Dan Hollands

    Dan Hollands Guest

    Use an ohm meter to measure the base emitter junction. If low ohms are read
    when the base is connected to the positive lead of the ohm meter and the
    collector is conntected to the negative lead then it is NPN

    Dan Hollands
    1120 S Creek Dr
    Webster NY 14580
  3. Pooh Bear

    Pooh Bear Guest

    *whith full detail* More homework ?

  4. Allen Bong

    Allen Bong Guest

  5. John Larkin

    John Larkin Guest

    On Wed, 21 Dec 2005 12:00:48 -0600,
    Hold the base lead in your right hand. Hold a scope probe tip in your
    left hand. Watch scope as you touch either of the other transistor
    leads to scope ground.


  6. me

    me Guest

    -spam.invalid (newone) wrote in
    look at the data sheet for it...
  7. Bob Monsen

    Bob Monsen Guest

    An NPN transistor is a two diodes that look like this:


    A PNP transistor is like this:


    Notice the direction of the diodes. If you have a multimeter with a diode
    test function, use that to see which it is by connecting the positive lead
    to the base, and seeing if there is a diode drop of about 0.6V to both of
    the other leads. If so, it is an NPN transistor. If not, try the negative
    lead on the base. If there is a 0.6V difference to both the other leads,
    it is a PNP transistor.
  8. Allen Bong

    Allen Bong Guest

    how to know the transistor is npn or pnp

    please whith full detail


    I just remember another way. It goes like this.

    First you get a Japanese analogue multi-meter (eg Sanwa 360YTR) and
    switch to X1K range. The reason for using Japanese meters is because
    its Red Probe carries -V while the Black Probe is +ve. The European
    meters are the other way round (I never own an US analog meter). So
    remember that if you use meters other than those made in Japan. The
    result would be opposite ie NPN->PNP & PNP->NPN.

    1. Put the R(ed) probe on C and B(lack) probe on E. The meter should
    be at infinity.

    2. Wet one of you fingers, if it is too dry, with some saliva and touch
    the B & C of the transistor that you are testing. Make sure that the
    emitter is not touched by your finger.

    3. If the meter swings, it's a PNP transistor. The more the meter
    swings, the higher the gain of the transistor.

    4. If the meter stays still, reverse the 2 probes ie. B probe on C and
    R probe on E. Repeat #2 again.

    5. If the meter swings now, it's an NPN transistor.

    6. Wipe you finger with a tissue paper.

    Of course there are a few assumptions made before you test the
    transistor. You must know the orientation of C, B & E before you
    perform the test. If the meter swings a little before you touch the
    Base, the transistor most probably is leaky. But if the C&E is having
    a resistance of approximately 50 ohms on both ways, it could be a FET



    | |
    | |
    | |RED PROBE
    |C |
    B |/ / \
    -----| (_/_)
    |> \_/
    |E |
    | |
    | |
    (created by AACircuit v1.28.6 beta 04/19/05
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day