The First Eleven. Part 7, Page 1. The Field Effect Transistor is a device which enables us to use one electrical signal to control another. The name 'transistor' is a shortened version of the original term, transfer resistor , which indicates how the device works.
Most transistors have three connections.
The effect is to make a 'resistance' whose value can be altered by the input signal. We can use this behaviour to 'transfer' patterns of signal fluctuation from a small input signal to a larger output signal. A wide variety of devices are called transistors. Figure 7.1 illustrates what this looks like. Three wires are then connected to the device.