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Circuits / Power

Zener regulator

Reversed, the Zener holds its voltage; R1 takes the rest of the supply

Zener regulator, simulated on a breadboard

Tap a part to see its voltages and currents. It is a model, not a measurement.

Predict, measure, explain

  1. Predict If the supply goes from 9 V to 12 V, how much does the voltage on R2 change?
  2. Measure Tap R2. Then change the supply to 12 V and tap it again.
  3. Explain
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    Very little: from 4.79 V to 4.89 V. The Zener takes the extra current (R1 goes from 9 to 15 mA) and holds the voltage.

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