Half-wave rectification
Figure 11.11 is a practical rectifier running from the mains.
Figure to be added
The step-down transformer first lowers the alternating voltage. The diode lets current through only in the direction X to L, so current flows through R only during the positive half of each cycle; in the negative half it is zero.
| t (cycles) | 0.25 | 1.25 |
|---|---|---|
| V | 1 | 1 |
Half-wave rectification
Only one half of each cycle reaches the output, so this is half-wave rectification.
Exercise 11.1 — the diode turned round
Keep the rest of the circuit as it is, but turn the diode round so its cathode is at X. Sketch how the current through R changes with time.
The answer
Now current flows only in the negative half-cycles, and the other way through R: the pulses are the same shape, below the axis.
| t (cycles) | 0.75 | 1.75 |
|---|---|---|
| V | -1 | -1 |