This project introduces the Transistor - the building block of almost all modern electronics. To make them work in your own circuit, you need to buy them along with some other basic parts such as batteries and leads to join everything up. Below is a list of the parts and a brief description of what they do.
1. 9V PP3 type battery. An alkaline one works best, but any will do.
2. Crocodile test leads for joining the circuit together. About 10 leads should be enough for most experiments.
3. Two Blue high quality LEDs. I say high quality to mean high brightness at a low current. With this type of LED you can make it light up even with a very very small amount of electricity. See the LED project. DO NOT CONNECT AN LED DIRECTLY ACROSS THE BATTERY. YOU MUST USE
FINGERS OR THE CIRCUIT BOARD AS SHOWN IN THE DIAGRAMS, OTHERWISE YOU MIGHT
BREAK THE LED.
4. A 6B pencil. It needs to be a very high B number, that is very soft, to make it easy to make dark thick lines.
5. Some cardboard - about 1mm thick. Can be any type really, but we will connect the crocodile leads to it, so a thickish type is easiest to use. 50mm x 50mm square is enough.
6. A general purpose small signal transistor such as a BC108.
The transistor being used has three terminals called:
These name are not important right now, but they do mean that each terminal is special in its own specific way. If you connect them the wrong way round, they will not work. If your circuit does not work, then most likely it is not connected correctly.
The circuit below uses a transistor to make the small amount of electricity flowing through you enough to make another LED very bright instead of only dim. There are two parts to the circuit.The first part - cicuit 1 - consists of you, the base, collector and first LED. This is similar to the LED project circuit where you could make an LED light with just a smallamount of electricity. Now we are using that small amount of electricity to make the second LED in circuit 2 very bright. The second part of the circuit consists of the collector, emitter, and second LED.
The leads on the transistor must be
connected correctly. The picture show the transistor from the bottom where the
leads come out from.
multiplication of electrons in the circuit – for every electron flowing through
the Base, 300 or so will be flowing through the Collector/Emitter.