EE 321 Lab
Prelab for Lab 6: DIODES AND ZENER DIODES CIRCUITS
Read the lab before answering these questions.
1) Consider the zener regulator shown in Figure 3.34 in Sedra and Smith.
Find R so that the zener current will be equal to 20 mA with no load
(use the conditions of part 1 of the lab).
Add a 1 k load to the circuit. Calculate the current in the load and the zener.
If the zener resistance rz = 10 ohms, how much will Vo change.
Find the spec for rz.
What is the load regulation with rz from the spec sheet.
What is the largest load current this regulator can deliver and still have
at least 1 mA in the zener? What load resistance does this imply?
What is the line regulation with rz from the spec sheet.
2) Consider the precision voltage source in Figure 1.
Find R to give the proper gain (4.2 v in and 10.0 V out)
with the pot set a its mid point.
- The circuit appears to have positive feedback. Why doesn't
it? Hint - if the output changes will the voltage at pin 3 change?
3) In the spec sheet find the voltage of a 4.3 V zener with only 0.1 mA
(look at fig 11, the 4.3 V zener has 4.3 V at 20 mA).
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