how to know the transistor is npn or pnp

how to know the transistor is npn or pnp

please whith full detail

An alternative would be to ask your friend to make the following circuit for you.

Allen

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.

Easy!

John

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

Graham

snipped-for-privacy@hotmail-dot-com.no-spam.invalid (newone) wrote in news: snipped-for-privacy@giganews.com:

look at the data sheet for it...

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

collector-----||-------emitter

A PNP transistor is like this:

collector----->|------base-------|

how to know the transistor is npn or pnp

please whith full detail

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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.

1. 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.

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

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

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

1. 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 (D&S).

Regards.

Allen

------------- | | | | | |RED PROBE |C | B |/ / \\ -----| (_/_) |> \\_/ |E | | | | |BLACK PROBE | | ------------| (created by AACircuit v1.28.6 beta 04/19/05