Basic Components (continued)

I have already explained the LED (Light Emitting Diode) now it is time to look at the Diode itself. A diode is an example of a Semiconductor, it is made of a material that exhibits properties of both an insulator and a conductor. Which property it takes in the case of electronic components will depend on how it is connected up and certain properties of the circuit itself. Semiconductors are usually made form the material Silicon. In the case of a diode electricity will run through it if it is connected with the tab pointing at positive volts. Diodes are useful for preventing current from flowing the wrong way and are needed to protect relays (rectifier diodes).

The transistor is another type of Semiconductor, it is a very useful component and is perhaps the best example of an interface device (A device that will enable Input and Output signals to be compatible with the control device) along with the relay. A transistor has three legs, the 'base'- Middle leg, 'emitter' leg marked (usually by a tab) and the 'collector'- the other leg. When the voltage exceeeds 0.7V at the base leg current will be able to flow through the collector and emitter. A transistor can therefore be used as a switch- a circuit with a low voltage output can switch on another circuit with a need for a high voltage input. The transistor therefore makes a good amplifier. Circuits will soon be published on this site, so don't worry if you don't quite understand all this yet.

An FET (Field Effect Transistor) is a special type of transistor that amplifies voltage in a circuit. The most popular type is the MOSFET power transistor. FETs have three legs like the transistor: The Gate- the middle leg, the source (the marked leg, usually on the right if you look at it from the front) and the drain. If the Voltage at the gate exceeds 2 Volts then the FET will amplify the voltage between the drain and the source. FETs are useful interface components like transistors. They are also very useful as they have a digital switching action, this reduces the 'bounce effect'- a jerky switching signal and clears it up into a crisp signal.