-SQA-SCOTTISH QUALIFICATIONS AUTHORITY
NATIONAL CERTIFICATE MODULE: UNIT SPECIFICATION
GENERAL INFORMATION
-Module Number-
2150206
-Superclass-
XL
-Title-
APPLIED ELECTRONICS 1
-Session-1996-97
-----------------------------------------DESCRIPTIONGENERAL COMPETENCE FOR UNIT:
Applying electronic engineering
principles to the design of analogue and digital electronic systems.
OUTCOMES
1.
design a signal conditioning subsystem;
2.
construct an electronic control system to meet a given specification;
3.
develop a combinational logic circuit.
CREDIT VALUE:
1 NC Credit
ACCESS STATEMENT: Access to this unit is at the discretion of the centre.
However it would be beneficial for the candidate to have completed the following
NC modules: 2330036 Energy; 2150156 Introduction to Control Systems (x2);
2150176 Introductory Applied Analogue and Digital Electronics; 2130036
Fundamentals of Technology: Mechanical Systems.
----------------------------------------For further information contact: Committee and Administration Unit, SQA,
Hanover House, 24 Douglas Street, Glasgow G2 7NQ.
Additional copies of this unit may be purchased from SQA (Sales and Despatch
section). At the time of publication, the cost is £1.50 (minimum order £5.00).
Unit No. 2150206
Continuation
NATIONAL CERTIFICATE MODULE; UNIT SPECIFICATION
STATEMENT OF STANDARDS
UNIT NUMBER:
2150206
UNIT TITLE:
APPLIED ELECTRONICS 1
Acceptable performance in this unit will be the satisfactory achievement of the
standards set out in this part of the specification. All sections of the statement of
standards are mandatory and cannot be altered without reference to SQA.
OUTCOME
1.
DESIGN A SIGNAL CONDITIONING SUBSYSTEM
PERFORMANCE CRITERIA
(a)
(b)
(c)
(d)
Data sheets are correctly interpreted in the selection of
operational amplifier configurations.
The graphic symbols used to represent electronic subsystems are
correct with respect to current standards.
Calculations to determine the operation of electronic subsystems
are correct.
A signal conditioning circuit is evaluated using appropriate circuit
equipment.
RANGE STATEMENT
The range for this outcome is fully expressed in the performance criteria.
EVIDENCE REQUIREMENTS
Oral/written and graphical evidence showing that the candidate can design a
signal conditioning system to meet a given performance specification on a
minimum of one occasion.
2
Unit No. 2150206
Continuation
OUTCOME
2.
DESIGN AN ELECTRONIC CONTROL SYSTEM TO MEET A
GIVEN SPECIFICATION
PERFORMANCE CRITERIA
(a)
(b)
(c)
(d)
For a given electronic system, each component is correctly
identified.
The operational characteristics of each subsystem is clearly
explained.
Calculations to verify the operational characteristics of each
subsystem are correct, with reference to data sheets.
The correct operation of the electronic system is confirmed.
RANGE STATEMENT
The range for this outcome is fully expressed in the performance criteria.
EVIDENCE REQUIREMENTS
Written and/or oral and graphical evidence of the candidate’s ability to design
and verify correct operation of a control system through calculation.
OUTCOME
3.
DEVELOP A COMBINATIONAL LOGIC CIRCUIT
PERFORMANCE CRITERIA
(a)
(b)
(c)
A suitable logic circuit is designed using suitable graphical
representation from a given specification.
A valid truth table is produced to predict the expected output.
The logic circuit is successfully evaluated using appropriate circuit
analysis equipment.
RANGE STATEMENT
The range for this outcome is fully expressed in the performance criteria.
EVIDENCE REQUIREMENTS
Written and/or oral and graphical evidence of the candidate’s ability to develop
specified combinational logic systems and to verify correct operation.
Performance evidence that the candidate can design and evaluate a
combinational logic circuit on a minimum of one occasion.
3
Unit No. 2150206
Continuation
-----------------------------------------
ASSESSMENT
In order to achieve this unit, candidates are required to present sufficient
evidence that they have met all the performance criteria for each outcome within
the range specified. Details of these requirements are given for each outcome.
The assessment instruments used should follow the general guidance offered by
the SQA assessment model and an integrative approach to assessment is
encouraged. (See references at the end of support notes).
Accurate records should be made of the assessment instruments used showing
how evidence is generated for each outcome and giving marking schemes
and/or checklists, etc. Records of candidates’ achievements should be kept.
These records will be available for external verification.
SPECIAL NEEDS
In certain cases, modified outcomes and range statements can be proposed for
certification. See references at end of support notes.
 Copyright SQA 1997
Please note that this publication may be reproduced in whole or in part for
educational purposes provided that:
(i)
(ii)
no profit is derived from the reproduction;
if reproduced in part, the source is acknowledged.
4
Unit No. 2150206
Continuation
NATIONAL CERTIFICATE MODULE: UNIT SPECIFICATION
SUPPORT NOTES
UNIT NUMBER:
2150206
UNIT TITLE:
APPLIED ELECTRONICS 1
SUPPORT NOTES: This part of the unit specification is offered as guidance.
None of the sections of the support notes is mandatory.
NOTIONAL DESIGN LENGTH: SQA allocates a notional design length to a unit
on the basis of time estimated for achievement of the stated standards by a
candidate whose starting point is as described in the access statement. The
notional design length for this unit is 40 hours. The use of notional design length
for programme design and timetabling is advisory only.
PURPOSE To develop the ability to design and construct analogue and digital
electronic systems.
SQA publishes summaries of NC units for easy reference, publicity purposes,
centre handbooks, etc. The summary statement for this unit is as follows:
On completion of this module you will have achieved the level of competence of
someone who is able to understand the function and operation of analogue and
digital electronic systems.
CONTENT/CONTEXT The candidate should achieve the level of competence
of someone who is able to understand the function and operation of analogue
and digital electronic systems.
Learning Outcomes 1 and 2 could be suitable for integrated assessment buy a
single assignment (an example covering both LO’s is included as an exemplar
assessment).
Outcome 1
The learning outcome is intended to enable the candidate to design signal
conditioning circuitry using operational amplifiers. Application data sheets may
be used as opposed to manufacturers data sheets (an exemplar sheet is
appended to the notes).
Evaluation of the circuit can be achieved by circuit construction and testing,
testing of pre-built circuits or by computer simulation techniques.
Examples of suitable subsystems and calculations are:
5
Unit No. 2150206
Continuation
Electronic subsystems: voltage divider; comparator; voltage follower; noninverting amplifier; inverting amplifier, difference amplifier.
Calculations:
voltage.
gain; input resistor; feedback resistor; input voltage; output
Test equipment: voltmeter, oscilloscope.
Outcome 2
The outcome is intended to develop competence in using input and output
transducers in electronic control systems. The transducers could be used with
the signal conditioning of LO1 to provide a complete control system.
The operation of the given system should be broken into subsystems for PC(b)
eg sensing system - Signal conditioning - Output system.
Suitable data sheets could include manufacturers device sheets, application
notes, supplier data sheets or summary sheets of transducer characteristics.
Correct operation of the circuits can be confirmed by circuit construction and
testing, testing of pre-built circuits or by computer simulation techniques.
Examples of suitable components, operational characteristics and calculations
are:
Electronic components: light; temperature; switches; resistors, potentiometers;
bipolar transistors; field effect transistors (standard and darlington pair
configuration); comparator operational amplifier; diodes; relays.
Operational characteristics: resistance change of sensors; saturation conditions
for transistors; saturation conditions for op-amps; load capability of relays.
Calculations: potential divider (sensor type, signal voltage, fixed resistor value);
transistor (base, emitter, collector current, current gain); output load.
Outcome 3
The outcome is intended to develop the candidates’ ability to design
combinational logic circuits to meet given specifications.
The specification for the outcome may take the form of a description of the
problem to be solved in a manner which would lead to a Boolean equation or the
Boolean equation itself together with a description of the problem that the circuit
is to solve.
The Truth Table is intended to allow the candidate to verify the correct operation
of the circuit drawn.
Evaluation of the circuits can be confirmed by circuit construction and testing,
testing of pre-built circuits or by computer simulation techniques.
An exemplar of LO3 is also included.
6
Unit No. 2150206
Continuation
Operational characteristics:
operating voltages;
impedance; logic voltages; output current; speed.
noise
immunity;
input
Common logic families: CMOS; TTL.
Logic gates: AND; OR; NOT; NAND; NOR; ExOR.
Method of analysis:
NAND equivalence.
truth table; Karnaugh mapping; Boolean simplification;
Machine Safety Interlock System
A drilling machine, driven by an electric motor must operate only when a set of
safety conditions are satisfied. The operation will be enabled by a ‘l’ (i.e. it is an
active HIGH line) on the output of a digital logic circuit.
The safe operational conditions are:
the power supply switch is operated (Assign ‘A’: active High)
the safety guard is in position (assign ‘B’ active High) AND
the motor overload current limit is not exceeded (Assign ‘C’: active High)
In addition to the above requirements, maintenance facilities must be provided
which allow the motor to run when:
(a)
(b)
a key is inserted (assign ‘D’: active High), the safety guard is NOT
closed.
the power supply switch is operated (A) and the motor overload
current limit is not exceeded (c).
This problem resulted in the following Boolean equation:
f = A.B.C + A.B.C.D
1.
Design a circuit to satisfy the above equation.
2.
Develop a Truth Table to show the outputs expected from this circuit.
3.
Using the Logic tutor Boards provided construct the circuit and hence
demonstrate its correct operation.
APPROACHES TO GENERATING EVIDENCE A candidate centred, resource
based approach to learning should be adopted in which candidates are
encouraged to complete assignments in an independent manner.
Corresponding to outcomes:
1.
Current Standards: BS3939 and PP7303
The candidates could be given a series of practical exercises which will
develop abilities to design signal conditioning and signal processing
systems.
7
Unit No. 2150206
Continuation
The exercises should be structured to develop candidates’ competencies
in using the operational amplifier configurations specified in the range
statements for each LO.
A tutor checklist could be used to verify successful completion of
exercises.
2.
The candidate could be given a series of graded exercises which
culminate in an assignment to measure ability to construct an electronic
system to a given specification.
The assignment should be broken down into a number of tasks in which a
candidate systematically selects a suitable input sensor, makes
calculations to ascertain values of passive components to produce
required op-amp and transistor switching levels, constructs the circuit and
evaluates the performance of the circuit to ensure correct operation.
3.
The candidate should be given a series of graded exercises which
culminate in an assignment to measure ability to develop a combinational
logic circuit to a given specification.
The assignment should be broken down into a number of tasks in which a
candidate systematically constructs a truth table, interprets the truth table
using a Boolean expression, simplifies the expression, draws the logic
circuit using NAND gates, and constructs and evaluates the circuit to
ensure correct operation.
A tutor checklist could be used to verify successful completion of
exercises.
The use of computer based circuit simulation and evaluation packages to verify
circuit design is to be encouraged.
ASSESSMENT PROCEDURES Example of instruments of assessment which
could be used for each outcome are as follows:
1-3.
The candidate could produce a brief report in a standard format which
contains evidence of the work undertaken in completing each
assignment.
An observation checklist could be kept by the tutor as evidence of
candidates completing practical assignment successfully.
A unit test could be used to assess knowledge and understanding and
ability to calculate as indicated in the range statement for each PC.
PROGRESSION
This unit progresses to the NC module 64320 Applied
Electronics 2. This unit forms part of the GSVQ in Engineering at Level III.
Candidates successfully completing the GSVQ in Engineering at level III will be
able to progress to an HNC/D programme in related disciplines.
8
Unit No. 2150206
Continuation
RECOGNITION
Many SQA NC units are recognised for entry/recruitment
purposes. For up-to-date information see the SQA guide ‘Recognised Groupings
of National Certificate Modules’.
REFERENCES
1.
2.
3.
4.
5.
Guide to unit writing. (A018).
For a fuller discussion on assessment issues, please refer to SQA’s
Guide to Assessment. (B005).
Procedures for special needs statements are set out in SQA’s guide
‘Candidates with Special Needs’. (B006).
Information for centres on SQA’s operating procedures is contained in
SQA’s Guide to Procedures. (F009).
For details of other SQA publications, please consult SQA’s publications
list. (X037).
 Copyright SQA 1997
Please note that this publication may be reproduced in whole or in part for
educational purposes provided that:
(i)
(ii)
no profit is derived from the reproduction;
if reproduced in part, the source is acknowledged.
9
Unit No. 2150206
Continuation
Operational Amplifiers: Application Data Sheets
1
The Inverting Amplifier
Rf
Ri
AV = V0/Vi = -Rf /Ri
V1
-
Rb = Rf || Ri
V0
+
Rb
2
The Non-inverting Amplifier
Ri
AV = l + Rf /Rl
V1
+
Ri = Rf || Rl
V0
-
Rf
R1
3
The Difference Amplifier
Rf
Ri
V0 = Rf /Ri (V2 - V1)
V1
If Rf = R1
V0
V2
Ri
V0 = V2 - V1
+
Rf
10
Unit No. 2150206
4
Continuation
The summing amplifier
Rf
If R1 = R2 = R3
R1
V1
V2
V0 = -(V1 - V2 -V3)
-
R2
V0
R3
V3
+
Rb
5
The Integrator
V0 =
−1
Vi. dt
C. Ri ∫
Rf
C
Rf is normally included to restrict low
frequency gain to stop instability -
Ri
it is typically selected to be about 10 x Ri
Vi
V0
+
R1
6
The High Pass Filter
Fc = 1/(2 Π CR)
Reversing 'R' and 'C' in
the circuit provides a
low pass filter.
V0
C
+
R
11
Unit No. 2150206
7
Continuation
The Comparator (with hysteresis)
NB Positve feedback used.
Input Switching points
Ri
Vi
V0
+
+ Vo. R1/(R1||Rf)
Rf
Ri = Rf || Rl
R1
12
Unit No. 2150206
Continuation
Restricted Response/Practical Exercise
Section (a)
Section (b)
Section (c)
Section (d)
+12V
R1
R2
10K
2K2
D1
RL1
IC1
VR1
2
-
Ic
7
10K
6
741
NORP12
1K
R4
Ib
R3
3 +
R5
TR1
2N1711
D2
4
2K2
LDR1
OV
OV
OV
-12V
Q1(a) From the circuit diagram shown, identify the following components:
R1 through R5
VR1
LDR1
D1, D2
IC1
TR1
RL1
Q1(b) With reference to the circuit diagram, explain the function of each section
(a) through (d).
Q1(c) Calculate the minimum and maximum voltages that can appear on pin 3
of the 741.
Q1(d) Calculate the minimum and maximum voltages that can appear on pin 2
of the 741.
Q1(e) Calculate 1c, 1b and R4 using the data sheets provided.
Contract the circuit and verify its operation.
13
Unit No. 2150206
Continuation
Machine Safety Interlock System
A drilling machine, driven by an electric motor must operate only when a set of
safety conditions are satisfied. The operation will be enabled by a ‘1’ (i.e. it is an
active HIGH line) on the output of a digital logic circuit.
The safe operational conditions are:
the power supply switch is operated (assign ‘A’ : active High),
the safety guard is in position (assign ‘B’ : active High) AND
the motor overload current limit is not exceeded (assign ‘C’ : active High).
In addition to the above requirements, maintenance facilities must be provided
which allow the motor to run when:
(a)
a key is inserted (assign ‘D’ : active High), the safety guard is NOT
closed
(b)
the power supply switch is operated (A) and the motor overload
current limit is not exceeded (C).
This problem resulted in the following Boolean equation:
f = A.B.C + A. B .C.D
(i)
Design a circuit to satisfy the above equation.
(ii)
Develop a Truth Table to show the outputs expected from this circuit.
(iii)
Using the Logic tutor Boards provided construct the circuit and hence
demonstrate its correct operation.
14