First it's helpfull to know how a transistor works. Actually, a transistor is just nothing more than a tiny switch, which you don't controll with your finger, but with an electronic signal. There are 3 pins on a transistor. A collector, a Base and an Emitter. If you put an electronic signal on the Base, the switch is open and electricity can flow through the Emitter and the Collector. In this instructable I show you how to make a transistor tester which shows you if the 3 pins are still working, and if they don't have a deffect.
We need a few components in for this.
1. piece of prototype board
2. battery clip
3. 330R resistor and a 22k resistor
4. some pieces of wire
5. a led (any color)
6. 9 volt battery
7. some old (or new) transistors
Also you need some soldering equipment.
Make the schematic and solder everything together. Take 3 pieces of wire which stick out the circuit board, where you put the transistor leads to it.
If you made everything just like the schematic, you're ready to test your tester! Take the three transistor leads, bend them a little and put the Base to the middle pin and the Collector and Emitter to the other pins.
If you want to make it more advanced, I put another schematic in the pictures selection. Here the NE555 timer switches the Base on and off, so you're sure that it's really working. This is a little bit heavier to make, because you also need a few more resistors and a capacitor, and a good prototype board. In my prototype board the holes are to far away from eachother, so a chip won't fit in it. You can also use a breadboard for this. Depending the resistors and capacitors you use, you can chanche the frequency from switching the Base.
Thanks for making my little, but verry effective project!
Cheers from Holland