3. Regulators. The forth element of the power supply unit shown in
figure 1-42 is the regulator.
The purpose of the regulator is to
provide an output voltage with little or no variation.
sense changes in output and compensate for the changes.
may also be designed to regulate the current flow.
regulators may be classified as series or shunt (parallel), depending
on their relative location in the circuit.
Figures 1-42A and 1-42B
modern practical applications, solid-state devices are used in
Figures 1-42C and 1-42D show shunt and series
regulators employing solid-state components.
extensively in regulator circuits.
A zener diode blocks current
until a specified voltage is applied.
When the zener voltage is
reached, the zener diode conducts, thus regulating the voltage
developed across it.
Probably no single event has had the impact on
electronics as has the discovery of the transistor. Transistors have
Additionally, transistors have been designed to
perform functions not previously attainable with vacuum tubes.