Basic Electronics (3110016)

Transistor as a Switch – ON

• Transistor will become ON (saturation) when a sufficient voltage V is given to input.
• During this condition the Collector-Emitter voltage Vce will be approximately equal to zero, ie the transistor acts as a short circuit.
• For a silicon transistor, it is equal to 0.3 V. Thus collector current ${\mathrm{I}}_{\mathrm{c}} = \raisebox{1ex}{${\mathrm{V}}_{\mathrm{cc}}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{R}}_{\mathrm{c}}$}\right.$ will flows.

Transistor as a Switch – OFF

• Transistor will be in OFF ( cutoff ) when the input Vin equal to zero.
• During this state transistor acts as an open circuit and thus the entire voltage Vcc will be available at collector.