©
2011 Technological Studies
Standard Grade Credit
Finalised Marking Instructions
 Scottish Qualifications Authority 2011
The information in this publication may be reproduced to support SQA qualifications only on
a non-commercial basis. If it is to be used for any other purposes written permission must
be obtained from SQA’s NQ Delivery: Exam Operations Team.
Where the publication includes materials from sources other than SQA (secondary
copyright), this material should only be reproduced for the purposes of examination or
assessment. If it needs to be reproduced for any other purpose it is the centre’s
responsibility to obtain the necessary copyright clearance. SQA’s NQ Delivery: Exam
Operations Team may be able to direct you to the secondary sources.
These Marking Instructions have been prepared by Examination Teams for use by SQA
Appointed Markers when marking External Course Assessments. This publication must not
be reproduced for commercial or trade purposes.
Mark Allocation
1.
Marks
KU RNA
(a)
 RNA
Light Sensor/
LDR
Set
light level
-
Control
Unit
+
TD/
Transducer
driver/
Output driver
(transistor)
Lamp
Desired
light level
2
1
0

RNA
(b)
Control diagram
(c)
Compares the set level to the feedback level
 KU
2.
2
1
0
 KU
 KU
1
0
(a)
Light Dependent Resistor
(b)
As the light level increases the LDR’s resistance decreases.
As the light level increases Vout increases.
The variable resistor acts as a sensitivity control etc
 KU
1
0
3
2
1
0
 RNA for each correct descriptive statement up to 3.
(c)
(i)
(ii)
400
Vout
1
0
(-420 )
=
R1
 VCC
R2
=
1500
5
1900
=
3·95 V
FTE
 RNA for substitution
 RNA for answer from given working
Page 2
2
1
0
Marks
KU RNA
2.
(continued)
(d)
Complete the circuit diagram to show how a diode could be used to
protect the transistor from back-voltage (e.m.f.).
1
0
 KU for diode symbol
 RNA for wiring
 RNA for orientation of diode
(e)
The transistor is fully switched on when VBE is 0·7 V.
(i)
Saturated/saturation
 KU
1
0
(ii)
collector
1 Base
2 Emitter
 KU for each correct
2
1
0
( KU if names reversed)
(f)
(i)
It allows a low powered circuit to control a high powered
circuit. There is no physical link between the circuits.
Control circuits can’t work with very high currents
2
1
0
 KU for each correct answer up to 2
(ii)
(iii)
SPST/
Single Pole Single Throw
SPDT/
Single Pole Double Throw
 KU
 KU
DPDT/Double Pole Double Throw
Page 3
2
1
0
 KU
1
0
2
1
0
Marks
KU RNA
3.
(a)
1
0
 RNA
(2 lines)
 RNA
Valve 
 RNA
Component A
 RNA
all 3 shuttle pipes
 KU for at least 1 correct pilot line
(b)
(i)
(ii)
Component A
Valve 1
Reservoir
 KU
3/2/Pilot/Spring Return
Page 4
1
0
3
2
1
0
0
4
3
2
1
0
Marks
KU RNA
3.
(continued)
(c)
A1
=
r2
=  × 152 = 706mm2
=
r
= ×5
 RNA for correct area
calculation
A2
2
2
= 78mm
2
ATOTAL =
A1 – A2
= 628mm2
F
628 × 0·5
= 314N
=
1
4
3
2
1
0
 RNA for subs
 RNA for ans from working
(if only using A1 max 2 marks)
(d)
 RNA for combined area
Reduce area of cylinder
 KU
Larger piston rod diameter
2
Reduce main air pressure
 KU
Page 5
2
1
0
Marks
KU RNA
4.
init:
symbol counter = b0
for counter = 1 to 3
‘set for ... next loop to 3
OR
clean:
low 7
high 6
 RNA
let pins = %0100000
‘cleaning head down
 RNA
 RNA

RNA
for both
pause 5000
OR
low 6
high 7
let pins = %10000000
pause 5000
alternative
position for low 7
OR
high 5
low 7
label:
OR
let pins = 0
next counter
 RNA
let pins = %00100000
 RNA
if pin0 = 0 then label
 RNA
let pins = %00000000 or low 5
 RNA
return
 RNA
If candidates do not switch off pin then max – 2 marks
Page 6
9
8
7
6
5
4
3
2
1
0
Marks
KU RNA
5.
(a)
 RNA time in seconds calculation
Ee
(b)
(i)
=
=
ItV
7 × (20 × 60) × 120
=
1008000 J
=
1 MJ
3
2
1
0
 RNA for substitution
 RNA for answer from given working
 = useful power out
total power in
=
17×8
=
23
 RNA for substitution
 RNA for answer from
0·774 (77·4%)
2
1
given working
0
(ii)
 RNA
(c)
2
1
0
Energy is lost/due to friction etc or sound/heat
 RNA
Reduces energy consumption
 KU
Reduces cost of running system etc
(d)
(i)
1
 KU
Coal/gas/oil
2
(ii)
each up to 2
1
0
2
1
0
Energy source can be replenished/won’t run out
Reduces pollution/greenhouse gas etc
Uses less resources
 KU each up to 2
Page 7
2
1
0
Marks
KU RNA
6.
(a)
Z=
(A•B) + (B•C)
2
1
0
 RNA for ANDing inputs
 RNA for OR conditions
Alt (A•B•C) + (A•B•C) + (A•B•C)
A
0
0
0
0
1
1
1
1
(b)
B
0
0
1
1
0
0
1
1
C
0
1
0
1
0
1
0
1
Z
0
0
0
1
0
0
1
1

3
2
1
0


 RNA each correct entry
(c)
(d)
Protects the LED (from large current)
 KU
Characteristic
TTL
1
0
CMOS

Large fan out

Higher power consumption

Easily damaged by static electricity

Faster switching speed

Can use supply voltages from 3-18 V
 KU for each correct single entry
Page 8
4
3
2
1
0
7.
(a)
Marks
KU RNA
1
0
Electrically Erasable Programmable Read Only Memory
(b)
Name
Function
ROM
Stores PBASIC language
for microcontroller
operations.
Data remains after
power is switched off.
RAM
Stores data required
Data will not remain
when running the
when power is
program.
removed.
Stores the program.
Data remains after
EEPROM
Characteristic
power is switched
off.
Data can be re-written.
4
3
2
1
0
 KU for each correct entry
(c)
(i)
V
mark
space
t
 KU for pulsed/on-off signal
 KU for identifying/describing mark and space
 KU for identifying/describing that speed is determined by
3
2
1
0
mark/space ratio
(ii)
Maintains a high torque/smooth turning
Only required 1 output pin from microcontroller
Page 9
1
0
Marks
KU RNA
8.
(a)
CWM = ACWM
(1600 × 0·8) + (1200 × 2) + (1000 × 3) = F × 4
F=
6680
4
 RNA for transposition
= 1670 N
(b)
1
 RNA for substitution
 RNA for answer from given working
Lubrication/ball bearing/using alternative materials
2
(c)
(i)
3
2
1
0
 KU each up to 2
Speed of Drum
2000 × 1 = 50 × X
X=
2000
50
cir = d
= 3·14 × 0·1 m
= 0·314 m
 RNA for
circumference
= 40 rev/min
Speed of Load
2
1
0
 RNA for drum speed
Drum speed × Circumference
= 40 × 314
= 12560 mm/min
OR
= 0·2 m/s
3
2
1
0
 RNA for answer
from working
(ii)
Part A
Wheel
 KU
Part B
Worm
 KU
2
1
0
 KU total if answers reversed
(d)
(i)
Rack & Pinion
(ii)
Crank & Slider
 KU
 KU
[END OF MARKING INSTRUCTIONS]
Page 10
1
0
1
0