Voltage Regulator Circuits:
Mostly electronic circuits need a stable DC voltage source for several purposes. As pointed out earlier, usually DC voltage is obtained by rectification and filtering of an ac signal obtained from AC mains through a step down Transformer. Such a DC voltage does not remain constant while load changes. A voltage regulator is an electronic circuit which helps in maintaining a constant voltage across the load regardless of variation of load current (of course, over a specified range of load current). Even though several voltage regulators are available currently as off-the-shelf ICs, in the following, we discuss uA 723 voltage regulator. The block diagram of a typical IC voltage regulator 723 is illustrated here in Figure
Figure: Block Diagram of 723-type IC Voltage Regulator
The above scheme may be systematically described on the basis of the following basic circuits.