Rectifier Diodes and Circuits

 Semiconductor rectifier diodes are PN junctions with P type semiconductor for anode and N type semiconductor for cathode. They are used to convert alternating current to direct current and is widely used in various electronic devices. Simplest form is a half wave rectifier which uses only a single diode and the output has only half of the alternating current as output. It is a pulsating DC at the frequency of the input AC waveform. Full wave rectifier uses a couple of diodes fed out of phase using a centre tapped transformer so that both halves of the AC waveform appears in the output as a pulsating DC with twice the frequency of the supply voltage. Bridge rectifier uses four diodes and a transformer without a central tap. The output waveform is just like that of the full wave rectifier with two diodes. As both these are DC with ripples, smoothening out of the waveform can be done by using a high value capacitor across the output. Further smoothening out can be done using an inductor in series. A resistor parallel to the capacitor can also smoothen the waveform a bit more and such a circuit is known as an RC filter (Resistance-Capacitor).