How can a transistor be used as a switch? Transistor as an Automatic Switch:In a transistor switching circuit as shown in Figure, a fixed resistor, R1 and a variable resistor, R2 form a potential divider. By varying the value of the variable resistor, the voltage applied to the base terminal can be adjusted to switch the transistor on or off. If the variable … [Read more...] about How can a transistor be used as a switch?