4.1 Semiconductors

4.1.1 Diodes

(a)

1. Diode symbols;
2. Diode characteristics and properties;
3. Diodes in series and parallel;
4. Main characteristics and use of silicon controlled rectifiers (thyristors), light emitting diode, photo conductive diode, varistor, rectifier diodes;
5. Functional testing of diodes.

(b)

1. Materials, electron configuration, electrical properties;
2. P and N type materials: effects of impurities on conduction, majority
3. and minority characters; PN junction in a semiconductor, development of a potential across a PN junction in unbiased, forward biased and reverse biased conditions;
4. Diode parameters: peak inverse voltage, maximum forward current, temperature, frequency, leakage current, power dissipation;
5. Operation and function of diodes in the following circuits: clippers, clampers, full and half wave rectifiers, bridge rectifiers, voltage doublers and triplers;
6. Detailed operation and characteristics of the following devices: silicon controlled rectifier (thyristor), light emitting diode, Shottky diode, photo conductive diode, varactor diode, varistor, rectifier diodes, Zener diode.

4.1.2 Transistors

(a)

1. Transistor symbols; Component description and orientation;
2. Transistor characteristics and properties.

(b)

1. Construction and operation of PNP and NPN transistors;
2. Base, collector and emitter configurations;
3. Testing of transistors.
4. Basic appreciation of other transistor types and their uses.
5. Application of transistors: classes of amplifier (A, B, C);
6. Simple circuits including: bias, decoupling, feedback and stabilisation;
7. Multistage circuit principles: cascades, push-pull, oscillators,
8. multivibrators, flip-flop circuits
9. (b) Description and operation of logic circuits and linear circuits;
10. Introduction to operation and function of an operational amplifier used as: integrator, differentiator, voltage follower, comparator;
11. Operation and amplifier stages connecting methods: resistive capacitive, inductive (transformer), inductive resistive (IR), direct;
12. Advantages and disadvantages of positive and negative feedback.

4.2 Printed Circuit Boards

1. Description and use of printed circuit boards.

(a)

1. Understanding of the following terms: Open and closed loop, follow up, servomechanism, analogue, transducer, null, damping, feedback, deadband;
2. Construction operation and use of the following synchro syst components: resolvers, differential, control and torque, E and I transformers, inductance transmitters, capacitance transmitters,
3. synchronous transmitters;
4. Servomechanism defects, reversal of synchro leads, hunting