Zener shunt regulator

This circuit shows the design of a basic zener shunt regulator. You begin the design by picking a zener that gives you the required voltage. The resistor, Rs, can then be calculated using the formula. This resistor allows enough current to flow through the zener to maintain the voltage regulation while passing current to the load. If Rs is too large, the zener will be "starved" for current when the load draws to much. If Rs is too small, the zener will pass too much current and it may exceed the power dissipation rating of the zener. The power dissipation in the zener is given by Pz.