Introduction to Electronics
Week 5 Quiz Answer
Week 5 Quiz
Question 1)
Consider a diode circuit shown below.
Assume that each diode can be modeled as an ideal diode in series with a voltage source, having Vf=0.7V.
The resistor has a value of R1=10Ω.
Check all statements that are true
- When any of the diodes are ON, the voltage across that diode is 0.7 V.
- When Vin is in between the positive and negative limits of Vout, Vo=Vin.
- If V1=2.3V and V2=2.3V, then Vo has a positive limit of 3 Volts and a negative limit of -3 Volts.
- When R1 is replaced with a resistor with higher resistance, the Voltage Transfer Characteristics (VTC) curve changes.
Question 2)
Which of the following are TRUE? Select all that apply.
- To have a smoother output voltage from an ac to dc converter, one must use a smaller filter capacitor.
- The order of stages in a DC power supply from input to output is a transformer, rectifier, then lastly a filter.
- If the input is a sinusoidal signal, the output of a half-wave rectifier will have the same frequency as the input.
- If the input is a sinusoidal signal, the output of a full-wave rectifier will have the same frequency as the input.
- If the diodes in the rectifiers are non-ideal, the output voltage of a full-wave rectifier is smaller than that of a half-wave rectifier.
Question 3)
A limiter is implemented using two non-ideal diodes, each modeled as an ideal diode in series with a voltage Vf volts. If the input voltage is a 5V amplitude sine wave, what is the minimum output voltage?
- 2Vf
- −5
- Vf
- -5 + 2Vf
Question 4)
In the rectifier below, the resistance Rs of the voltage source has been included to see how it affects the output voltage. If R=300Ω, RS= 100Ω, and Vin is a sinusoidal voltage with amplitude 10V, what is the maximum output voltage Vout in volts?
The diodes are ideal.
(It may help to redraw the circuit with diodes replaced by short and open circuits as appropriate)
Answer: 7.5
Question 5)
For the circuit shown and the given input voltage, which of the following plots is the correct output voltage versus time? The diode in the circuit is modeled as an ideal diode in series with a voltage source Vf = 0.65V.
- D
- C
- A
- B
Question 6)
A diode circuit and sinusoidal input signal are shown. The diode is modeled as an ideal diode in series with a voltage source Vf = 0.7V.
What value resistor should be used so that the maximum diode current is 10 mA? Give your answer in ohms to the nearest ohm.
Answer: 230
Question 7)
For the circuit and input of problem 6:
If R = 510 Ω, what is the magnitude of the diode current at t = 400μs? Give your answer in milliamps.
Answer: 0
Question 8)
For the circuit and input of problem 6:
If R = 510 Ω, what is the magnitude of the diode current at t = 700μs? Give your answer in milliamps.
Answer: 4.2
Question 9)
Select all of the statements that are NOT true.
- Loading of a voltage source may be reduced by lowering the source resistance.
- A diode circuit with three regions of operation (three states) has three corners on its VTC plot.
- The envelope of an AM voltage waveform is a plot of the peak voltage of the carrier signal versus frequency.
- A diode envelope detector with a relatively large time constant can act as a peak detector.
- The voltage transfer characteristic of an ideal voltage regulator is a line of slope 1.
Question 10)
For the input and output waveforms shown, which of these sets of (Vin, Vout) points contains only points that are on the VTC?
- 0.5,2) (3,3) (-2,0)
- (1.5,5) (0.5,0.5) (3,2)
- (0,0) (5,2) (-0.5,0)
- (-2,-1) (0,0) (4,2)
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