In the circuit of Fig. P1.80 let R1 5 20 kV and R2 5 10 kV, and let both diodes have VZ 5 4.3 V and VD(on) 5 0.7 V. (a) Sketch and label the VTC. (b) Repeat if R1 is removed from the circuit. (c)...

In the circuit of Fig. P1.80 let R1 5 20 kV and R2 5 10 kV, and let both diodes have VZ 5 4.3 V and VD(on) 5 0.7 V. (a) Sketch and label the VTC. (b) Repeat if R1 is removed from the circuit. (c) Repeat parts (a) and (b) if D1 is replaced with a 6.8-V Zener diode while D2 remains the same.