Unit 39 Electronic Principles

Unit 39:

Electronic Principles

Unit code:

QCF level:

Credit value:


This unit aims to further develop learners’ understanding of analogue electronics and their applications across the engineering sector.

Unit abstract

In this unit, learners will examine the use of current manufacturers’ data and support, apply current circuit analyses and design, implement and then test the created applications.

Although fault-finding skills are not the main emphasis of the unit they will form an integral part in the later development, in terms of testing.

Learning outcomes

On successful completion of this unit a learner will:

1     Be able to apply testing procedures for semiconductor devices and circuits

2       Understand the characteristics and operation of amplifier circuits

3     Understand the types and effects of feedback on circuit performance

4       Understand the operation and applications of sine wave oscillators.

Unit content

1      Be able to apply testing procedures for semiconductor devices and circuits

Circuits and testing: half and full wave rectifying; zener regulator; switching and amplifier circuits for transistors; IC voltage regulators instruments eg CRO, probes, signal generators, multi-meter, logic

Devices: semiconductor devices eg diodes (rectifier characteristics including forward/reverse bias modes, zener, LED, photodiode, thyristor, triac), transistors (bipolar, unipolar and field-effect, including characteristics and switch and amplifier modes), photo-transistors, opto-couplers, integrated circuits (741 operational amplifier applications including filters, comparators, power supplies and oscillators), IC voltage regulator, ‘specialist’ ICs (analogue and digital)

Literature: manufacturers’ specifications; manuals; characteristics; circuit diagrams and support (online and offline)

2      Understand the characteristics and operation of amplifier circuits

Amplifier characteristics: ideal (gain, bandwidth, input/output impedance, noise, thermal drift); common notation; DC/AC behaviour; op-amp basic circuits; limitations (DC, AC, non-linear, power); common applications; internal circuitry of 741 (differential, voltage and output amplifier)

Analyse operation and performance: use of quantitative methods; equivalent circuits; computer modelling; consideration of frequency response; voltage gain; bandwidth; output power; distortion; input and output impedance

Types and benefits of amplifier: power eg single-ended Class A, complementary symmetrical Class B, Class AB; tuned; small-signal; operational amplifiers eg inverting, non-inverting, voltage follower, differential, summing, integrator, differentiator, comparator, instrumentation, Schmitt trigger; active filters (high-pass, low-pass, band (pass, reject), notch)

Modify circuit designs: using manufacturers’ data; circuit calculations; to meet revised specifications using alternative components to achieve lower cost or to improve performance

3      Understand the types and effects of feedback on circuit performance

Types and effects of feedback: types eg voltage, current, series, shunt; effects eg closed loop gain of a system with feedback, feedback in single and multi-stage circuits

Circuit performance: effect of feedback on gain, bandwidth, distortion, noise, gain stability, input and output impedance

Circuits: single-stage transistor amplifier; operational amplifier

Investigate: circuit design and build, practical measurement; computer simulation

4      Understand the operation and applications of sine wave oscillators

Circuit requirements: circuit conditions eg 1-βA = 0 at only one frequency, gain-phase relationship in the circuit; frequency determining elements

Build and evaluate: to a given specification a typical circuit configuration eg Wien Bridge, Twin-T, three-section R-C ladder, L-C coupled, transistor or operational amplifier

Specification: factors eg frequency, stability, frequency drift, distortion; need for amplitude stabilisation

Crystal oscillators: advantages of crystal controlled oscillator circuits eg frequency accuracy and stability; equivalent circuit of a quartz crystal; fundamental and overtone circuits

Learning outcomes and assessment criteria

Learning outcomes
Assessment criteria for pass

On successful completion of
The learner can:

this unit a learner will:

LO1 Be able to apply testing

apply testing procedures to a range of semiconductor

procedures for

devices and circuits

semiconductor devices and

use relevant literature for testing semiconductor devices


and circuits

LO2 Understand the

analyse the operation of different types of amplifier

characteristics and operation

evaluate the actual performance of different types of

of amplifier circuits


compare the analysis with the measured results

modify circuit designs to meet revised specifications

LO3 Understand the types and

describe types of feedback and determine the effects on

effects of feedback on circuit

circuit performance when feedback is applied


design a circuit employing negative feedback

investigate the effects of applying feedback to single and

multi-stage circuits

LO4 Understand the operation

describe the circuit conditions and the methods used to

and applications of sine

achieve sinusoidal oscillation

wave oscillators

build and evaluate a sine wave oscillator to a given


explain the advantages of crystal-controlled oscillator



This unit may be linked to Unit 1: Analytical Methods for Engineers and Unit 5: Electrical and Electronic Principles.

Essential requirements

Centres must ensure that learners have access to appropriate laboratory test equipment (eg signal generators, oscilloscopes, digital frequency meters, audio power meters and test meters).

Employer engagement and vocational contexts

The delivery of this unit will benefit from centres establishing strong links with employers willing to contribute to the delivery of teaching, work-based placements and/or detailed case study materials.