A general filter circuit is shown in figure

If $${R_1} = {R_2} = {R_A}$$ and $${R_3} = {R_4} = {R_B},$$ the circuit acts as a

The block diagram of two types of half wave rectifiers are shown in figure. The transfer characteristics of the rectifiers are also shown within the block

It is desired to make full wave rectifier using two half wave rectifiers. The resultant circuit will be

The input signal $${V_{in}}$$ shown in the figure is a $$1$$ $$kHz$$ square wave voltage that alternates between $$+7V$$ and $$-7V$$ with a $$50\% $$ duty cycle. Both transistors have the same current gain, which is large. The circuit delivers power to the load resistor $${R_L}.$$ What is the efficiency of this circuit for the given input? Choose the closest answer.

The switch $$'S'$$ is the circuit of the figure is initially closed. It is opened at time $$t=0.$$ You may neglect the zener diode forward voltage drops. What is the behavior of $${V_{OUT}}$$ for $$t > 0$$