SIMPLEST TRANSISTOR TEST

The simplest transistor tester uses a 9v battery, 1k resistor and a LED (any colour).
Keep trying a transistor in all different combinations until you get one of the circuits
below. When you push on the two leads, the LED will get brighter.
The transistor will be NPN or PNP and the leads will be identified:

The leads of some transistors will need to be bent so the pins are in the same positions

as shown in the diagrams. This helps you see how the transistor is being turned on.

This works with NPN, PNP transistors and Darlington transistors.