Diode rectifier: keep one half of an AC waveform

The circuit

The example connects an AC source to a diode and load resistor. During the forward half-cycle, current flows through the diode and resistor. During the reverse half-cycle, the diode blocks current, so the output across the resistor is near zero.

A real silicon diode has a forward voltage drop. The exact drop changes with current, temperature and the diode model. The fast educational engine is useful for the concept; Engineering accuracy mode uses a nonlinear junction model.

Try it in resistor.dev

1. Open the example and run the simulation.
2. Put the input and load resistor on separate oscilloscope channels.
3. Compare the sine wave with the output: one half-cycle is missing.
4. Reverse the diode to pass the opposite half-cycle.
5. Change the signal amplitude and resistor value, then observe current and resistor power.

From pulses to DC

A half-wave rectifier produces pulses, not smooth DC. A filter capacitor across the load can store charge between peaks and reduce ripple. A bridge rectifier uses four diodes to use both halves of the AC waveform. In a real power supply, account for diode current, reverse-voltage rating, capacitor ripple current and transformer or source limits.