How do i know if a transistor is npn or pnp????

How do i know if a transistor is npn or pnp???? plz HELP

orksecurity6 years ago
If you can find the numbers, that's the easy solution.

Many years ago, I built a very simple 1.5V one-transistor audio oscillator (circuit diagram can easily be found), then replaced the transistor with three test leads. If they're hooked up correctly to the terminals of a working PNP transistor, the circuit beeps; if they aren't, it doesn't. I suppose one could do an NPN version too. These also give you a basic "has the magic smoke escaped" tester. If you really want to get fancy, you could put in a rotary switch that scrambled the order of the leads appropriately so you don't have to unhook and rehook each time, but I suspect the 3-pole-8-throw (or 16-throw) rotary switch wouldn't be cheap. Could also be done under control of a bit of digital electronics, but that gets more complicated.

Fancy transistor testers can tell you some of the characteristics of the transistor. Really fancy ones can plot its transfer curve. But unless you have reason to believe it's damaged or can't find the numbers, hitting the references really is an easier way to get that info.
lemonie6 years ago

Pick a number off the case, Google "(number) datasheet"

If you can identify the base collector and emitter, measure it as a diode. If the thing conducts +on the base to emitter adn collector, its PNP, if its the other way, its NPN