3.Frequency Multiplier Circuits
4.Voltage Multiplier Circuits
Let us examine each of these applications with some considerable detail.
The process of converting AC into DC is called rectification. Diodes can be used as half wave rectifiers and full wave rectifiers. Half Wave Rectifier:
In the Half wave rectifier circuit shown above the transformer serves two purposes. 1.It can be used to obtain the desired level of dc voltage (using step up or step down transformers). 2.It provides isolation from the power line.
The primary of the transformer is connected to ac supply. This induces an ac voltage across the secondary of the transformer. During the positive half cycle of the input voltage the polarity of the voltage across the secondary forward biases the diode. As a result a current IL flows through the load resistor, RL. The forward biased diode offers a very low resistance and hence the voltage drop across it is very small. Thus the voltage appearing across the load is practically the same as the input voltage at every instant. During the negative half cycle of the input voltage the polarity of the secondary voltage gets reversed. As a result, the diode is reverse biased. Practically no current flows through the circuit and almost no voltage is developed across the resistor. All input voltage appears across the diode itself. Hence we conclude that when the input voltage is going through its positive half cycle, output voltage is almost the same as the input voltage and during the negative half cycle no voltage is available...