ESP1104 Introduction to Electronic Systems Khursheed
Tutorial 4
1) Determine the diode current in the following circuit using the load-line method.
The diode I-V curve is shown below
Compare the operating diode current to the estimate found by assuming that there is a 0.6V across the diode, what is the percentage difference?
1
500 Ω
500Ω 5 V
2) The I-V curve for a Light Emitting Diode is given below for two different ranges of applied voltage. The estimated maximum power dissipation limit is 1040 mW and it was noted that the LED started to light at around 3 mA.
Describe what is happening inside the LED for points A and B. If we have a 9 V battery, and connect this LED in series with a resistor, what range of resistors should we use with this LED?
3) A transformer steps down mains power (50 Hz) to 32 volts rms. Assume that you have you have 4 diodes, 1 kΩ (5 Watt), 20 Ω (0.5 Watt) resistors, and two 1000 μF capacitors to make a rectifier circuit. Calculate the ripple value (peak to peak) and the output DC voltage for half-wave rectification and full-wave rectification. What reduction of the ripple size can be expected if you were to incorporate an RC filter in either case?
Imagine you are now given a 16 V Zener Diode rated at 125 mW. You measure the peak voltage after full-wave rectification (with no RC filter) and it is 39 V. What is the range of possible series resistance values required when using the Zener Diode as a regulator for this circuit?
2
A
B
0 5 10 15 20 25
0 0.5 1 1.5 2 2.5
Applied voltage (volts)
Diode Current (mA)
0 50 100 150 200 250
0 1 2 3 4 5 6
Applied voltage (volts)
Diode Current (mA)
