The circuit of Fig. is an example of feedback of the following type

For full wave rectification, a four diode bridge rectifier is claimed to have the following advantages over a two diode circuit:

(1) less expensive transformer

(2) smaller size transformer, and

(3) suitability for higher voltage application.

Of these,

In a series regulated power supply circuit, the voltage gain A_v of the ‘pass’ transistor satisfies the condition:

One input terminal of high gain comparator circuit is connected to ground and a sinusoidal voltage is applied to the other input. The output of comparator will be