4.1 Semiconductors
4.1.1 Diodes
(a) Diode symbols;
Diode characteristics and properties;
Diodes in series and parallel;
Main characteristics and use of silicon controlled rectifiers (thyristors), light emitting diode, photo conductive diode, varistor, rectifier diodes;
Functional testing of diodes.
(b) Materials, electron configuration, electrical properties;
P and N type materials: effects of impurities on conduction, majority and minority characters;
PN junction in a semiconductor, development of a potential across a PN junction in unbiased, forward biased and reverse biased conditions;
Diode parameters: peak inverse voltage, maximum forward current, temperature, frequency, leakage current, power dissipation;
Operation and function of diodes in the following circuits: clippers, clampers, full and half wave rectifiers, bridge rectifiers, voltage doublers and triplers;
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) Transistor symbols;
Component description and orientation;
Transistor characteristics and properties.
(b) Construction and operation of PNP and NPN transistors;
Base, collector and emitter configurations;
Testing of transistors;
Basic appreciation of other transistor types and their uses;
Application of transistors: classes of amplifier (A, B, C);
Simple circuits including: bias, decoupling, feedback and stabilisation;
Multistage circuit principles: cascades, push-pull, oscillators, multivibrators, flip-flop circuits.
4.1.3 Integrated Circuits
(a) Description and operation of logic circuits and linear
circuits/operational amplifiers.
(b) Description and operation of logic circuits and linear circuits;
Introduction to operation and function of an operational amplifier used
as: integrator, differentiator, voltage follower, comparator;
Operation and amplifier stages connecting methods: resistive
capacitive, inductive (transformer), inductive resistive (IR), direct;
Advantages and disadvantages of positive and negative feedback.
4.2 Printed Circuit Board
Description and use of printed circuit boards.
4.3 Servomechanisms
(a) Understanding of the following terms: Open and closed loop systems, feedback, follow up, analogue transducers;
Principles of operation and use of the following synchro system components/features: resolvers, differential, control and torque, transformers, inductance and capacitance transmitters.
(b) Understanding of the following terms: Open and closed loop, follow up, servomechanism, analogue, transducer, null, damping, feedback, deadband;
Construction operation and use of the following synchro system components: resolvers, differential, control and torque, E and I transformers, inductance transmitters, capacitance transmitters, synchronous transmitters;
Servomechanism defects, reversal of synchro leads, hunting.