Regulated power supplied (Part 3)

A Zener diode allows current in the forward direction like a regular diode

but also conducts in reverse when the voltage exceeds a specific Zener breakdown voltage (Zener voltage).

Common Zener diodes: 500mW BZX55 and 1.3W BZX85, like BZX55C7V5 (7.5V).

Zener diodes can be series-connected with silicon diodes for various reference voltages.

Power Transistor

The transistor consists of three layers: NPN or PNP. The collector current (Ic) is dependent on the base current (IB). A change in base current IB results in an amplified change in collector current Ic. The ratio of these currents ranges from 15 to 100 and called beta ẞ.