Download ETEE3211 Fall 2004

ETEE3211
Fall 2004
Test #1
Name:__________________
Show all work. Clearly indicate final answer(s).
1. (15 points) A silicon diode is placed in a circuit and is operating at 85oC. At 25oC the diode
has a 0.68V drop. What is the voltage drop of the diode when in the circuit?
2. (25 points) For the circuit shown to the right,
sketch (and explain clearly) the output voltage
waveform vout when the input voltage (vs) is a
100Vrms sine wave. Use VON=0.7V and Rf=0.
3. (30 points) Determine the value of the capacitor
needed to provide filtering for the circuit shown so
that the voltage does not drop below 12V. Assume
Rf=0 and VON=0.7V. Sketch the output waveform.
4. ( 30 points) The zener regulator shown uses a
20V zener diode to maintain a constant 20V
across the load resistor, Rload. If the input
voltage varies from 32V to 42V and the load
current varies 200mA to 400mA, select the
value of Ri to maintain the constant voltage
across the load. Determine the power rating
required for the resistor and the zener diode.
Extra Credit: (25 pts maximum) Assuming no loss in the rectifier diodes of the full-wave
rectifier shown below, and with n=2, what is the value of Ri needed to maintain Vload at 16V with
a load current of 500mA? Vs varies between 110 and 120Vrms at 60Hz. The minimum voltage to
the regulator may reflect a ±4V ripple. Assume VZ=16V and RZ=0. Determine the size of the
capacitor and the value of the resistor required.