Stepdown Transformer: - The function of step down transformer is to step down the voltage from the ac mains (from 230v AC) to the required voltage level (say, 12v AC). Step up and step down of transformer is depends upon the turn’s ratio of the transformer. The output of the transformer is then given to the rectifier as a input.
Rectifier: - The function of rectifier is to convert AC (Voltage or current) into DC (Voltage or current). The input to a rectifier is AC whereas its output is unidirectional, but pulsating DC. Generally a full wave rectifier is used for rectification. The output of rectifier is then given to filter as a input.
Filter: - The output of rectifier is pulsating DC voltage due to ripple factor (AC components). Filter is used to remove ripple factor and to obtain pure DC output. Filters like C filter or capacitor filter, LC filter (inductor-capacitor filter), inductor filter or L filter, π type filter or CLC filter are used to obtain ripple free output. The output of filter is then given to regulator as a input. Capacitor filter blocks DC and pass AC, inductor filter blocks AC and pass DC.
Regulator: - In final stage, regulator is used to provide the constant output irrespective of changes or fluctuations in input. Transistorized series/shunt regulators, fixed and variable IC regulators or a zener diode regulator can be used as a regulator. Fixed voltage regulator IC’s like 78XX and 79XX are used to obtained fixed values of voltages at the output. And variable voltage regulator IC’s like LM 317 and 723 are used to adjust output voltage to a required constant value.
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