Zener shunt regulator: line and load regulation

Objective

Hold a 5.1 V output while the input and the load change, and measure line and load regulation.

Procedure

1. Run and read the output voltage.
2. Change the input from 10 V to 14 V and note the small change.
3. Change the load to 470 Ω.

Theory

The Zener takes the excess current: Iz = (Vin − Vz)/Rs − Vz/RL. Line regulation = ΔVout/ΔVin; load regulation = ΔVout/ΔIload. Both are small while Iz stays above a few mA.

Questions to answer

1. What limits the regulator when the load current rises?

Components used

Battery / DC source, 2 × Resistor 220 ohm 1/4W, Zener Diode 5.1V

About the model

Ideal wires; component models as listed in the catalogue (no parasitics, no temperature drift). Built without a breadboard so the schematic stays readable.

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