Unit 5: Electrical and electronic design
LO4: Be able to use semi-conductors in electrical and
electronic design – Diodes and transistors
Learner activity sheet
Activity 1
The picture shown here is for a diode. Diodes are semiconductor devices and perform a fundamental
function in electrical and electronic circuits.
1. Explain the function of a diode and how it work. Include in your explanation what a p-n junction
is, and how the diode can be forward or reverse biased.
2. Examine a data sheet for a typical diode (such as the 1N4001 or 1N4148) and explain the
following:
a. Maximum repetitive reverse voltage
b. Maximum reverse current
c. Maximum forward current
March 2015
Activity 2
The transistor is another form of semiconductor device, and works on a similar principle to the diode
except it contains two p-n junctions.
The transistor can function as a switch or as part of an amplifier.
1. Draw a circuit in which a single transistor is used as a switch, and explain how it works.
2. Draw a circuit of a single transistor (common emitter) amplifier, and explain how it operates.
3. Examine a data sheet for a transistor (such as the BC108 or 2N3055) and explain the following:
a. Maximum collect current (Ic max)
b. Maximum voltage collector-emitter (VCE max)
c. Total power (PTOT max)
d. Gain (hFE typical)
March 2015