a) Determine the output of the circuits above for a sinusoidal input V_i. What are their functions? Build the circuits and verify their operation. Use 1N4007 or 1N4148 diodes. What is the role of R_L in the second circuit? Vary its value and verify.

b) Determine the oscillation frequency and amplitudes at V_o1 and V_o2 of the circuit above. How can you change the amplitude at V_o1 without changing the frequency? How do you change the frequency without changing the amplitude?

Build the circuit with R₁=R₂ and verify its operation. Connect the circuits in (a) above to V_o1 of the oscillator and verify that things work as expected.

c) Build the ring oscillator. Adjust C to obtain an oscillation frequency of a couple of kHz. Determine the amplitude and frequency of operation with V_sup varying from 3V to 9V. Design a circuit that gives a dc output proportional to the output amplitude of the oscillator. Build and verify.