Ammeters,
Voltmeters etc,
for Class Use
R151
2
0
4
6
8
10
Ammeters, Voltmeters etc, for Class Use
R151
January 2008
January 2008
CONTENTS
1.
2.
3.
4.
5.
6.
7.
Scope of this guide
Survey of schools
The National Curriculum requirements
Useful definitions
Factors influencing choice
Meters currently available
Types of ammeters and voltmeters
7.1
Single function, single range, analogue meters
7.1.1
Educational OTK / TickiT
7.1.2
GLOBE
7.1.3
Harris
7.2
Dual function, multiple range, analogue meters
7.2.1
Dual scale SDAR
7.2.2
Dual scale GLOBE
7.2.3
Ravencourt 205 range
7.2.4
Dual scale Harris meter
7.2.5
Unilab Basic student meter
7.2.6
GLOBE PA221 basic meter 90
7.2.7
GLOBE triple scale meters
7.3
Single function, single range, digital meters
7.3.1
GLOBE & TickiT
7.3.2
Timstar
7.3.3
SATZ
7.3.4
IPC
7.4
Dual function, multiple range, digital meters
7.4.1
Unilab Easy Read
7.5
Multimeters, analogue
7.5.1
Draper AMM1
7.5.2
Rapid 105DMM
7.6
Multimeters, digital
7.6.1
JPR UNI-T UT20B
7.6.2
Rapid 212 pocket
7.6.4
Ravencourt SATZ UT30B
7.6.5
Economatics Skytronic
7.6.6
Rapid 318
7.6.7
CALTEK CM2400T
7.6.8
jtw DT830D+
7.6.9
Draper DMM1A
7.6.10
UNI-T 39A
7.6.11
SATZ 51
7.6.12
CALTEK CM3900A
7.6.13
UNI-T UT60A
8. Galvanometers
9. Repairs to meters
10. Disposal of meters
Appendix 1 Manufacturers' and suppliers' addresses
Page
1
1
2
3
3
4
4
5
6
7
8
9
9
10
11
12
13
14
15
16
17
18
19
20
21
21
22
24
25
26
28
29
30
31
32
33
34
35
36
37
38
39
40
40
41
43
CLEAPSS would like to acknowledge the help of all the technicians and teachers who completed the
questionnaire and provided further more detailed information about their use and experiences with electrical
meters. We would also like to thank the staff of a wide range of suppliers for their help in providing samples
of meters for laboratory testing and for the additional information they gave.
This guide replaces R151 Ammeters etc 1998.
Strictly confidential
Circulate to members and associates only
As with all CLEAPSS materials, members and associates are free to copy all
or part of this guide for use in their own establishments.
®
© CLEAPSS , The Gardiner Building, Brunel Science Park, Uxbridge UB8 3PQ
Tel: 01895 251496; Fax: 01895 814372; E-mail: science@cleapss.org.uk; Web site: www.cleapss.org.uk
R151 AMMETERS AND VOLTMETERS FOR CLASS USE
1.
Scope of this guide
This guide brings up-to-date information on ammeters and voltmeters suitable for
secondary school pupil use, up to and including Key Stage 4. It does not attempt to
address post-16 needs directly but would be useful to those considering purchasing for
students studying at this level. It replaces the last edition published in 1998. Relatively few meters are made in this country now and suppliers are constantly reviewing
sources in Europe, the Far East and South Africa as well as updating existing models.
For a further discussion about electrical measurement see the CLEAPSS Laboratory
Handbook (on the Science Publications CD-ROM), sections 10.3 and 12.3.
2.
Survey of schools
To help in gathering information for this guide, a small-scale survey of schools was
carried out. CLEAPSS would like to thank all those who replied and helped with
further discussions. Of over thirty schools which responded, eight covered the age
range 11 to 16, whilst the rest covered different ranges of pupil ages up to 18, mainly
11 to 18. While the sample is small, conversations with technicians suggest that the
summary results shown below are reasonably typical of many other schools.
Table 1
Use of analogue and digital meters
•
In Key Stage 3, almost twice as many of the sample schools now use digital
ammeters and voltmeters as use analogue meters. The main reason given was that
pupils find it easier to read the current or voltage from digital meters which was
one of the main purposes of the scientific activity involved.
•
In Key Stage 4, classes more schools use digital meters than analogue but the
difference was not quite as marked as in Key Stage 3. In part this is because
teachers believe that interpretation of analogue scales is an additional useful skill
to be encouraged.
•
About 1/6th of the schools responding use multimeters throughout. These are also
more widely used in schools with post-16 pupils.
•
Post-16 pupils are encouraged to make greater use of analogue meters.
Table 2
Replacement of meters
•
A very large majority of schools in all categories replace meters less frequently
than annually.
•
The main reason given was that they bought meters that were of better quality, as
far as their limited finances permitted. This sometimes meant that they could buy
fewer meters.
•
Another significant reason given was that it had become increasingly difficult in
the schools’ experience to get manufacturers to undertake repairs or to find a small
independent repair company which would do it economically.
•
Those schools which had opted to use multimeters throughout regarded this as a
good investment since one set of meters covered use as both ammeter and
voltmeter.
1
Table 3
Problems with meters
•
The most frequently-reported problem is with pupils overloading circuits and
blowing fuses where these are used for protection.
•
A second problem is that younger pupils sometimes use the wrong range on
multimeters. This has led a number of schools to use multimeters mainly with
older pupils.
•
In a few instances, schools reported problems with connections for 4 mm plugs
which had been insufficiently soldered.
3.
The National Curriculum
The National Curriculum includes teaching which requires pupils to use ammeters
and voltmeters themselves (as well as sometimes having their use demonstrated).
Extracts from the National Curriculum are given below in Table 4.
Table 4
Electricity and magnetism requirements in the National
Curriculum at key stages 3 and 4
NATIONAL CURRICULUM
The relevant parts of the programme of study for science at key stages 3 and 4 states that the following
should be covered:
Key Stage 3
3.1
Energy, electricity and forces.
3.1a
Energy can be transferred usefully, stored, or dissipated, but cannot be
created or destroyed.
3.1c
Electric current in circuits can produce a variety of effects.
Explanatory notes Energy: This includes the properties and behaviour of light and sound, renewable
energy resources and emerging technologies such as fuel cells.
Circuits: This includes current and voltage in series and parallel circuits.
Variety of effects: Electrical devices are designed to make use of a variety of effects
caused by electric currents, including heating, chemical changes and magnetic
effects.
Key Stage 4
7
Energy, electricity and radiations.
7.a
Energy transfers can be measured and their efficiency calculated, which is
important in considering the economic costs and environmental effects of
energy use.
7.b
Electrical power is readily transferred and controlled, and can be used in a
range of different situations.
Meters which can measure current and voltage are thus required in class sets.
Galvanometers are also useful for classwork or demonstrations investigating the
principles of electromagnetic induction and so on but the prime concern of schools will
be to maintain class sets of ammeters and voltmeters for which a considerable sum of
money would be required. As such sets are expensive it is important that care is taken
to ensure that meters purchased are reasonably resistant to damage.
2
4.
Useful definitions
Table 5
Useful definitions
SOME DEFINITIONS
Meter
Descriptions
Analogue
Digital
Single-function
Dual-function
Value shown by a pointer on a scale or a bar of variable
length on a display screen.
Value shown by digits on a display screen.
Either an ammeter or a voltmeter, not both.
Both an ammeter and a voltmeter.
Single-range
Dual-range
For example, covers only 0 - 1 A or 0 - 10 A, not both.
For example, both 0 - 1 A and 0 - 10 A.
Multi-range
Multi-purpose
For example, 0 - 1 V, 0 - 5 V, 0 - 10 V and 0 - 50 V.
Is made both dual-function and multi-range by the
attachment of
shunts (devices to give various current ranges) and
multipliers (devices to give various voltage ranges).
Digital multimeter This is made both multi-function and multi-range by the
(DMM)
use of a switch, usually a rotating one.
Shunt
A shunt is a device which can be connected to a meter to
adapt it to enable it to read a specified range of current,
eg, 0 to 10 mA.
Multiplier
A multiplier is a device which can be connected to a meter
to adapt it to enable it to read a specified range of
voltages, eg, 0 to 100 mV.
Galvanometer
Historically this was the name given to a moving-coil,
electric-current detector but is now mainly used to denote
a device which can measure the magnitude and direction
of very small electric currents. It may be used, for example,
to detect a null or unbalanced condition in a bridge or
potentiometer circuit. Whilst a centre-zero meter is ideal,
some of the models in the analogue meters described
below would meet some of the uses to which a
galvanometer may be put.
5.
Arrangement of
terminals and switches
Varies.
At least three terminals
(or a slider).
Two.
Three terminals
(or two and a switch).
Three or more.
Two.
Two, three or
occasionally four.
-
Factors influencing choice
The major factors are as follows.
Analogue or digital display - Teachers may hold different views about the relative
merits of analogue and digital meters, as indicated in the survey results. Digital
displays are now widespread in everyday domestic and commercial life. Digital
instruments are easier to read than analogue ones and the survey showed that many
teachers favour the use of digital meters with younger pupils, especially when the
experiment is essentially about checking the voltage or current. However, not all
digital meters indicate current direction so clearly as do most analogue meters.
Robustness - On the whole, digital meters are more robust than analogue ones.
However they are significantly more expensive and this is especially important when
schools need class sets.
Understanding what is being measured - This is likely to be improved if the
meter is simple and has only one function and one range; eg, it measures only current
from 0 to 1 amp.
Ease of reading - Digital displays are easier to read than analogue scales. However,
some analogue scales are easier to read than others; eg, if intermediate graduations
are in tenths rather than fifths, quarters or thirds.
3
Control - If several functions and ranges can be obtained by choice of terminals or
with an accessible switch, then a teacher cannot be sure what pupils are reading. The
following list indicates possibilities in decreasing order of teacher control. Singlefunction, single-range meters; multi-purpose meters with single-range shunts and
multipliers; dual/triple range, single-function meters or multi-purpose meters fitted
with dual/triple range shunts and multipliers; digital multimeters.
Economy - A meter which can provide several functions and/or ranges, with or
without the fitment of additional shunts or multipliers, is more economical but may
have some of the disadvantages noted above. Schools also need to balance the merits
of cheaper meters which may not be easily repairable and should perhaps be
considered disposable, against more-expensive meters which might last longer and
may be repairable.
Price - Digital meters are significantly more expensive than analogue meters. Dualor multi-range meters are usually more expensive than single-range meters. Limited
budgets in many science departments may lead to a conflict of choice given the factors
above. However, as far as is financially possible, pupils should use both digital and
analogue electrical meters at some stage during key stages 3 and 4.
To improve the chances of accurate reading, most pupils at Key Stage 3 should use
only single function meters because multimeters are confusing for many.
6.
Student meters currently available
In order to help schools reach decisions about the purchase of meters, this guide has
been divided into the following sections or families of meters:
• single-function, single-range analogue meters;
• dual-function, dual- or triple-range analogue meters with, or without, separate
shunts or multiplers;
• single-range digital meters;
• multi-range digital meters;
• multi-range analogue multimeters;
• multi-range digital multimeters.
Schools choosing single-function, single-range analogue meters will find that most of
these are inexpensive but quite adequate for junior forms. Many of these cost around
£5 - 7 and it is hardly worth paying to have them repaired once out of the warranty
period, even if a repairer can be found.
Choosing digital meters poses more of a problem because the available single-function
meters cost between about £22 and around £40 each. One solution is to buy digital
multimeters at half this price and cover their fronts so that pupils are discouraged
from altering the function (see section 7.6).
The meters intended for pupil use were selected for review largely on the basis of cost
within a given category. A few, which might otherwise have been tested, were not
available from the suppliers or manufacturers so the list is not completely
comprehensive. In a few cases, models shown in the most-recent printed catalogue
had been deleted. On-line catalogues are usually more up-to-date but suppliers quite
often delete, add or modify models, especially multimeters. Similarly, whilst prices
were correct at the time of publication, costs fluctuate and schools are advised to
check firm prices before purchasing goods.
7.
Types of ammeters and voltmeters examined
Meters are manufactured in families, or series, as noted above. Within a family,
meters will have different functions, eg, ammeter, voltmeter, and different ranges,
eg, 0 - 1 A, 0 - 10 V, 0 - 10 A but often similar cases and appearance. A small number
of the suppliers and manufacturers contacted were not able to provide samples of
their ammeters and voltmeters for testing but the vast majority did.
4
7.1
Single-function, single-range analogue meters:
features examined and reported
Suspension
The moving-coil suspension is either pivoted, ie, the moving
coil is supported between points turning in fixed cups, or taut
band, ie, it is supported between two phosphor-bronze strips.
Taut-band meters should stand up better to school use but are
very much harder to find. The majority of those reviewed are
probably pivoted. The uncertainty is because many of the
suppliers do not know which method of suspension is used in
their meters.
Scale divisions
Size of each scale division is identified.
Scale length
Following the British Standard 89 recommendation, this is
measured as the length of the arc passing through the midpoints of the smallest divisions of the scale (the outer scale
where there are two).
Dimensions
Indicated in the table. They include the terminals.
Zero adjustment
The percentage of the scale length it covers. The greater it is,
the more likely that deviations caused by abuse can be
corrected.
Most have a plastic screw. Comment is made on whether the
adjustment screw is too prominent and easy to turn, so making
it easier for pupils to tamper with the equipment.
Robustness
Comment is made on the material of the case and its design,
eg, the presence of sharp corners etc.
Comment is made on the ability of the movement to withstand
mechanical shock; all analogue meters were subjected to
limited height-drop tests.
Mechanical stability: all were found to be stable.
Terminals
All are captive with 4 mm sockets and usually tightly fixed with
nuts and split washers. Some have locating pins and star
washers which are better.
Meters with two ranges, eg, 0 - 1 A and 0 - 10 A, will have three
terminals. The arrangement can be seen in the photographs.
Polarity indication Almost all have red and black terminals; some have + and - signs
as well.
Access
Comment is made on how easy it is for pupils to reach and
damage components and how easy it is for a repairer to reach
components.
Repairability
To replace damaged coils and hairsprings costs about as much
as the supply of a new meter and so is not usually worth while
once the meter is out of warranty. However, some
manufacturers will make a moderate charge for minor repairs
and adjustments, replacing covers etc. It is always worth asking
for a quotation.
See the Laboratory Handbook section 10.3.4 for advice on repair
including d-i-y repair. Section 9 of this guide also gives some
guidance on repair options.
Comments
Other significant features, if any, are mentioned.
Ranges and prices Ranges in the families; suppliers' catalogue numbers; references
to pages in this guide. Models measuring milliamps and
microamps are only mentioned if they are in the same series.
5
7.1.1
Analogue meters: TickiT and 'Educational' OTK
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Beecroft, Commotion,
Economatics, GLS, Granet,
Griffin Education 'economy',
Philip Harris, Optical Vision,
Scientific & Chemical,
Timstar 'value', YPO.
Moving coil pivoted.
0.02 A for 0 to 1 A.
0.2 V for 0 to 6 V.
68 mm.
h 53 mm d 120 mm w 80 mm.
8%. Easy adjustment with a
screwdriver.
Clear-plastic front cover. Tough,
white-plastic base. Smooth
corners. Movement stands up
well to mechanical shock.
4 mm or crocodile clip.
Clear: red and black; + and -.
Difficult for pupils. Easy for repairer with a tubular spanner or a nut driver.
It would probably not be worth sending meters away for repair once out of
warranty.
This meter is very good value at the low prices quoted.
Ranges available and prices
Ammeters
Voltmeters
Range
1A
2A
5A
6V
15 V
Beecroft
WELO-3801
£5.82
27013
£5.50
RA 3250
£5.25
G257133
£5.95
L408810
£6.50
EHA-380-010L
£7
B8A 74444
£5.87
0-1A
£5.99
EMA 010010
£6.20
EL06820
£5.99
-
WELO-3802
£6.39
27015
£5.50
RB 3250
£5.25
G405034
£5.95
-
WELO-3803
£6.39
27017
£5.50
RE 3250
£5.25
G405047
£5.95
L408840
£6.50
EHA-380-030H
£7
-
WELO-3804
£6.39
27019
£5.50
RD 3250
£5.25
G257146
£5.95
L408930
£6.50
EHB-450-010X
£7
B8A 74469
£6.79
0-6V
£5.99
EMV 010010
£6.20
EL06825
£5.99
467731
£4.50
WELO-3805
£6.39
27021
£5.50
RD 3250
£5.25
405060
£5.95
L408960
£6.50
EHB-450-020L
£7
B8A 74470
£6.79
0-15V
£5.99
EMV 010020
£6.20
EL06826
£5.99
46774x
£4.50
Commotion
Economatics
GLS
Granet
Griffin Education
Philip Harris
Optical Vision
Scientific & Chemical
Timstar
YPO
EHA-380-020Y
£7
B8A 74457
£6.79
0-2A
£5.99
EMA 010020
£6.20
EL06821
£5.99
-
6
0-5A
£5.99
EMA 010030
£6.20
EL06822
£5.99
467723
£4.50
7.1.2
Analogue meters: EDM-series GLOBE meter
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
ASCOL, Rapid.
Moving coil.
0.2 A for 0 to 10 A.
0.2 V for 0 to 10 V.
75 mm.
h 95 mm d 143 mm w 97 mm.
12%. Easy adjustment with a
screwdriver.
Clear-plastic face cover. Lightweight black-plastic base
(though for some makes the
casing may be red). Smooth
corners. Movement stands up
well to mechanical shock.
4 mm or crocodile clip.
Clear: red and black; + and -.
Three Philips head screws on
the base making access difficult
for pupils. Easy for repairer with
a long screwdriver.
It would probably not be worth sending meters away for repair once out of
warranty.
This meter seems to be good value.
Ranges available and prices
Ammeters
Voltmeters
Range
1A
3A
5A
10 A
3V
5V
10 V
15 V
ASCOL
P59-1050
P59-1060
P59-1070
P59-1080
P59-1110
P59-1120
P59-1130
-
£8.53
£8.53
£8.53
£8.53
£8.53
£8.53
£8.53
85-2579
85-2580
85-2581
85-2582
85-2593
85-2594
85-2595
85-2597
£4.50
£4.50
£4.50
£4.50
£4.45
£4.45
£4.45
£4.45
Rapid
Rapid also produces versions of the meter for the ranges 0 - 1 mA, 0 - 10 mA, 0 - 100 mA,
0 - 200 mA, 0 - 500 mA at prices ranging between £4.45 to £5.95. There are also microammeter
ranges of -20 to 100 µA and 0 to 500 µA at similar prices. Similarly ASCOL produces versions of
the meter for the ranges 0 - 1 mA, 0 - 100 mA, 0 - 500 mA at prices ranging between £8.53 to
£10.08. It also markets microammeter ranges of -20 to 100 µA and 0 to 500 µA at similar prices.
7
7.1.3
Analogue meters: Harris
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Philip Harris.
Moving coil pivoted.
0.02 A for 0 to 1 A.
0.2 V for 0 to 10 V.
60 mm.
h 65 mm d 95 mm w 83 mm.
10%. Easy adjustment with a
screwdriver.
Solid well-built blue-plastic
base. Clear-plastic face cover.
Smooth corners. Movement
stands up well to mechanical
shock.
4 mm or crocodile clip.
Clear: red and black; + and -.
Two Philips head screws on the base, making access difficult for pupils.
Easy for repairer with a long screwdriver.
It may be worth sending meters away for repair once out of warranty.
This meter is much more expensive but very solidly made.
Ranges available and prices
Ammeters
Voltmeters
Range
1A
5A
10mA
100mA
10 V
Philip Harris
B8A-74627
B8A-74639
B8A-74603
B8A-74615
B8A-74664
£31.84
£31.84
£26.22
£31.84
£31.84
8
7.2
Dual-function and dual- or triple-range analogue meters:
features examined and reported
7.2.1 Analogue dual-scale meter: SDAR SM1104/5 (ammeter/voltmeter) & TickiT
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Commotion, The Consortium,
Griffin Education, Rapid,
Timstar.
Moving coil pivoted.
0.02 A for –0.2 to 0.6 A.
0.1 A for –1 to 3 A.
0.1 V for -1 to 3 V.
0.5 V for -5 to 15 V.
80 mm.
h 97 mm d 133 mm w 95 mm.
About 12%. Very positive
movement.
Clear-plastic front cover. Lightweight, black-plastic base.
Slightly sharp basal corners.
Movement stands up to mechanical shock.
4 mm or crocodile clip.
Clear: red and black; + and -.
One small Philips head screw
on the base, making it difficult
for pupils. Easy for repairer with
a small screwdriver.
It would probably not be worth sending meters away for repair once out of
warranty.
Large clear screen for readings. This meter is good value at the prices
quoted.
Ranges available and prices
Ammeters
Voltmeters
Range
-0.2 to 0.6 A & -1 to 3 A
-1 to 3 V & -5 to 15 V
Commotion
27047
27049
£6.99
£6.99
011816
011817
£7.45
£7.45
EHA 380 011J
EHA 380 013F
£7.80
£7.80
85-2578
85-2590
£4.50
£4.45
EL-06770
EL-06771
£7.25
£7.25
The Consortium
Griffin Education
Rapid
Timstar
Timstar also offers a 0 to 100 mA & 0 to 500 mA model, though this is much more expensive at
£26.70.
9
7.2.2
Analogue dual-scale meter: GLOBE EDM-series
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
ASCOL.
Moving coil.
0.1 V for 0 to 5 V.
0.333 V for 0 to 15 V.
0.02 A for 0 to 1 A.
0.1 A for 0 to 5 A.
71 mm.
h 97 mm d 133 mm w 95 mm.
9%. Very positive movement.
Clear-plastic front cover. Solid
black-plastic base. Smooth
basal corners. Movement
stands up to mechanical shock.
4 mm or crocodile clip.
Clear: red and black; - terminal
marked.
Single Philips head screw on
the base, making it difficult for
pupils. Easy for repairer with a
small screwdriver.
It would probably not be worth sending meters away for repair once out of
warranty.
The casing is identical with the models in 7.2.1 but the scale for the
voltmeters are different. Scale division magnitude on 0 to 15 volt range
make accurate readings more difficult to take on this model.
Ranges available and prices
Ammeters
Voltmeters
Range
0 to 1 A & 0 to 5 A
0 to 5 V & 0 to 15 V
ASCOL
P59-1090
P59-1150
£8.53
£8.53
10
7.2.3
Analogue dual-scale meter: Ravencourt Premium A205 (ammeter), V205
(voltmeter)
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Beecroft, Granet, Griffin
Education, Ravencourt,
Scientific & Chemical, Timstar.
Moving coil pivoted.
0.01 A for -0.2 to 1 A.
0.1 A for -1 to 5 A.
0.1 V for -1.7 to 5 V.
-0.5 V for -5 to 15 V.
90 mm.
h 105 mm d 100 mm w 90 mm.
9%. Positive movement using a
screwdriver.
Clear-plastic front cover.
Opaque black-plastic base with
substantial rubber feet screwed
in. Smooth basal corners.
Movement stands up to
mechanical shock.
4 mm or crocodile clip.
Clear: red and black; - terminal marked.
Two Philips head screws below the front face, making it difficult for pupils.
Easy for repairer with a small screwdriver.
It may be worth checking on repair options once out of warranty.
Anti-parallax mirror improves chances of accurate readings.
Ranges available and prices
Ammeters
Voltmeters
Range
-0.2 to 1 A & -1 to 5 A
-1.7 to 5 V & -5 to 15 V
Beecroft
WELO-3904
WELO-4404
£26.50
£26.50
L409190
L409310
£20.50
£20.50
EHA 550 010Q
EHA 560 010J
£23.55
£23.55
A205
V205
£17.80
£17.80
EMA 050 010
-
Granet
Griffin Education
Ravencourt
Scientific & Chemical
£19.07
Timstar
ELO 6775
ELO 6815
£19.00
£19.00
11
7.2.4
Analogue dual-scale meter: Harris (separate ammeters & voltmeters)
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Philip Harris.
Moving coil pivoted.
0.02 A for 0 to 1 A.
0.1 A for 0 to 5 A.
60 mm.
h 65 mm d 95 mm w 85 mm.
About 12%. Needs a screwdriver to turn, has positive
movement.
Clear-plastic front cover.
Very solid blue-plastic base.
Smooth basal corners.
Movement stands up to
mechanical shock.
4 mm or crocodile clip at rear of
meter.
Clear: red and black; + and - terminal marked on meter face.
Two Philips head screws below the front face making it difficult for pupils.
Easy for repairer with a small screwdriver.
It would be worth checking on repair options once out of warranty.
More expensive but solidly made.
Ranges available and prices
Ammeters
Voltmeters
Range
0 to 1 A & 0 to 5 A
0 to 5 V & 0 to 15 V
Philip Harris
B8A 74597
B8A 74640
£36.92
£35.59
12
7.2.5
Analogue Unilab Basic Student meter using shunts & multipliers
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
Philip Harris
Moving coil pivoted
0.02 A for -0.2 to 1 A.
0.1 A for -1 to 5 A.
60 mm
h 80 mm d 100 mm w 150 mm.
About 10%. Positive movement
using a screwdriver.
Clear-plastic front cover. Very
solid grey base. Smooth basal
corners. Movement stands up to
mechanical shock.
4 mm or crocodile clip.
Clear: red and black; terminal marked.
Two Philips head screws below the front face making it difficult for pupils.
Easy for repairer with a small screwdriver.
It would be worth checking on repair options once out of warranty.
This is a much more expensive meter but will serve as both an ammeter and
a voltmeter over a range of current and voltage magnitudes using
appropriate shunts or multipliers. Can also be used to measure ac currents.
Ranges available and prices
Ammeter / Voltmeter
Range
Meter only
Shunts & multipliers
Philip Harris
B8H 30981
Shunts cover the ranges: 1 to 5 A, 50 mA to 100 mA, 1 mA to 10 mA.
£46.35
Multipliers cover the ranges: 1 to 5 V, 5 to 10 V, 10 to 50 V.
Prices vary but are in the region of about £10 to 12 each.
(Ac shunts & multipliers are more expensive)
13
7.2.6
Analogue dual-purpose, multi-range GLOBE PA-221 Basic meter 90
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
ASCOL, Beecroft, Commotion,
Griffin, Rapid, STE.
Moving coil pivoted.
1 unit for -10 to 50 units.
2 units for -20 to 100 units.
84 mm.
h 57 mm d 113 mm w 165 mm.
Zero adjust
About 8%. Positive movement
using a screwdriver.
Robustness
Clear-plastic top cover. Solid red or blue metal base (depending on the
supplier). Smooth top corners though basal corner inclines to be sharper.
Four rubber feet. Movement stands up to mechanical shock.
4 mm or crocodile clip.
Positive terminals are black for current ranges and red for voltage ranges; terminal marked.
Four Philips head screws, slightly inset on the base, making it difficult for
pupils. Easy for repairer with a small screwdriver.
It may be worth checking on repair options once out of warranty.
This meter is converted from ammeter to voltmeter using a sliding device.
There is a choice of four ranges for each of current and voltage measurement with current maxima of 100 µA, 100 mA, 1 A and 5 A and voltage
maxima of 100 mV, 1 V, 10 V and 50 V. The face indicates whether the
meter is being used as an ammeter or voltmeter. For less-able pupils there
is a danger of confusion about which sockets to use and which scale to
read. Nevertheless, this is a very versatile meter at the price.
Terminals
Polarity indication
Access
Repairability
Comments
Ranges available and prices
Ammeter / Voltmeter
Range
Various
ASCOL
P59-3996
£17.05
Beecroft
WELO-4801
£31.36
Commotion
27051
£15.00
Griffin
EHA-800-010R
£21.65
Rapid
85-2576
£10.90
STE
10565
£13.91
14
7.2.7
Analogue triple-range GLOBE ammeter and voltmeter
Suppliers
Suspension
Scale divisions
Scale length
Dimensions
Zero adjust
Robustness
Terminals
Polarity indication
Access
Repairability
Comments
ASCOL, Rapid.
Moving coil.
0.1 A for 0 to 5 A.
1 mA for 0 to 50 mA.
10 mA for 0 to 500 mA.
0.1 V for 0 to 3 V.
0.5 V for 0 to 15 V.
10 V for 0 to 300 V.
80 mm.
h 97 mm d 133 mm w 95 mm.
About 10%. Positive movement
using a screwdriver.
Clear-plastic top cover. Solid
black-plastic base. Reasonably
smooth corners. Movement
stands up to mechanical shock.
4 mm or crocodile clip.
Black-coloured common
terminal & three red ones for
each different current or voltage
connection; the - terminal is
marked.
Three Philips head screws, slightly inset on the base, making it difficult for
pupils. Easy for repairer with a small screwdriver.
It would probably not be worth sending meters away for repair once out of
warranty.
A very large screen makes reading easier.
Ranges available and prices
Ammeter
Ranges
Voltmeter
0 - 50 mA, 0 - 500 mA, 0 - 5 A
0 - 3 V, 0 - 15 V, 0 - 300 V
ASCOL
P59-1140
£8.53
Rapid
85-2577
85-2590
£4.50
£4.45
Rapid also sell triple scale voltmeters (0 to 3 V / 10 V / 15 V and 0 to 3 V / 15 V /30 V) both at
similar prices to those above.
15
7.3
Single-function, single-range digital meters:
features examined and reported
Display
3 ½ digit liquid-crystal display is the most common with a
nominal height of 0.5" (12 - 13 mm). 3 ½ means that the maximum reading (omitting the decimal point) is 1999, so 4 ½
means 19999 etc. Thus readings on a 20 V meter would be from
0.00 to 19.99 V.
Battery & low The most common battery used is the PP3, (9 V). Most have
battery indication a means of indicating when the battery strength is low, eg, by
flashing ‘LOW BATT’ sign.
Polarity indication A negative sign in front of the display indicates reversed
connections.
Overload
When the load is greater than the maximum capable of being
displayed, the display usually shows ‘1’. Since most ammeters
are rated at 10 A, their shunts will be overloaded before this
indication but will withstand minor overloads for some time.
On/off switch
Almost all have on/off switches.
Dimensions
Indicated in the table. They include the terminals.
Resistance
All 10 A ammeters have a resistance of 0.01 ohms. Not
commented on further.
Robustness
Comment is made on the material of the case and its design,
the presence of sharp corners etc.
Terminals
All are captive with 4 mm sockets and tightly fixed with nuts
and split washers. Meters with two ranges, eg, 0 - 1 A and
0 - 10 A, will have three terminals. The arrangement can be
seen in the photographs.
Polarity indication Almost all have red and black terminals; some have + and - signs
as well.
Access
Comment is made on how easy it is for pupils to reach and
damage components and how easy it is for a repairer to reach
components.
Repairability
As noted in Section 9 of this guide, repairs to digital meters are
not usually within the scope of schools and may affect the
warranty. Costs of digital meters are much higher than those for
analogue so schools are advised to contact suppliers direct. Not
commented on further.
Uncertainty
This is usually less than that for analogue bench meters and
sufficient for pre-sixth form work and indeed much sixth form
work as well. Not commented on further.
Resolution
Indicates level of accuracy. Typically this will be in steps of
0.01 A or 0.01 V.
Comments
Other significant features, if any, are mentioned.
Ranges and prices Ranges in the families; suppliers' catalogue numbers; references
to pages in this guide.
16
7.3.1
Digital single-purpose GLOBE & TickiT ammeters & voltmeters
Suppliers
Display
Battery
On/off
Resolution
Beecroft, Commotion, Granet,
Rapid, YPO.
3 ½ digit liquid crystal.
9 V PP3 or 6F22 battery;
‘LOBAT’ sign indicates
replacement need.
On/off sliding switch
0.02 A for 0 to 10 A or
0.01 V for 0 to 20 V.
Dimensions
h 75 mm d 165 mm w 100 mm.
Robustness
Fawn-plastic case with four
small rubber feet on base. Fairly
robust.
4 mm sockets only on front of
casing.
Red and black; + and - terminal
marked.
Terminals
Polarity indication
Access
Comments
Battery reached via a sliding panel, giving easy access for all. Four Philips
head screws, slightly inset on the base making it difficult for pupils to access
circuits. Easy for repairer with a small screwdriver.
More modestly priced than most digital meters. Good range of meters
available from Rapid but both basic meters also available from Commotion.
Ranges available and prices
Ammeter & Voltmeter
Ranges
Ammeters 0 - 10 A, 0 - 2 A, 0 - 200 mA, 0 - 200 microA
Voltmeters 0 - 20 V & 0 - 2 V
Rapid
85-2572 to 85-2575
85-2570 to 85-2571
All priced at £19.50
Both priced at £19.50
Ammeter 0 - 10 A
Voltmeter 0 - 20 V
WELO-4001
WELO-4501
£22.50
£22.50
27065
27063
£22.50
£22.50
L409550
L409500
£20.00
£20.00
467553
467545
£14.75
£14.75
Beecroft
Commotion
Granet
YPO
17
7.3.2
Digital single-purpose Timstar Premium ammeters & voltmeters
Suppliers
Display
Battery
On/off
Resolution
Rapid, Timstar.
3 ½ digit liquid crystal.
9 V PP3 battery; display fades
for low battery.
On/off sliding switch.
0.02 A for 0 to 10 A or
0.02 V for 0 to 20 V.
Dimensions
h 44 mm d 155 mm w 80 mm.
Robustness
Solid plastic case (white for
ammeter, black for voltmeter).
4 mm sockets.
Red and black; +/- shown on
casing.
Four inset screws on the base,
making it difficult for pupils.
Sliding cover hard to remove to
replace battery.
-
Terminals
Polarity indication
Access
Comments
Ranges available and prices
Ammeter & Voltmeter
Ranges
Ammeter 0 - 10 A
Voltmeter 0 - 19.99 V
Rapid
85-1640
85-1635
£27.50
£27.50
ELO 6829
ELO 6828
£23.00
£23.00
Timstar
18
7.3.3
Digital single-purpose SATZ ammeters & voltmeters
Suppliers
Display
Battery
On/off
Resolution
Beecroft, Economatics, GLS,
Granet, Griffin Education,
Ravencourt, Scientific &
Chemical, Timstar.
3 ½ digit liquid crystal. - sign
indicates reversed polarity.
9 V PP3 battery; 'BATT' signal
on LHS of screen indicates
need for replacement.
On/off press switch.
0.01 A for 0 to 10 A or
0.01 V for 0 to 20 V.
Dimensions
h 70 mm d 90 mm w 95 mm.
Robustness
Solid grey plastic case; smooth
corners. Reasonably robust.
4 mm inset
Red and black; +/- shown on casing.
Small, inset, Philips head screws on the base, making it fairly difficult for
pupils. Sliding cover removed to replace battery.
Terminals
Polarity indication
Access
Comments
Ranges available and prices
Ammeters & Voltmeters
Ranges
Ammeter 0 - 10A
Voltmeter 0 - 20V
Beecroft
ELO 4001
ELO 4501
£22.50
£22.50
ZA 010
ZV 020
£21.95
£21.95
G377578
G377565
£24.70
£24.70
L409470
L409450
£25.50
£25.50
EHA- 700P
EHA-750
£24.00
£24.00
ZA 010
ZV 020
£23.50
£23.50
EMV-100010
EMV-100010
£23.30
£23.30
EL18560
EL18562
£23.00
£23.00
Economatics
GLS
Granet
Griffin Educational
Ravencourt
Scientific & Chemical
Timstar
19
7.3.4
Digital single-purpose IPC ammeters & voltmeters
Suppliers
Display
Battery
On/off
Resolution
Griffin Educational,
Scientific & Chemical.
3 ½ digit liquid crystal.
9 V PP3 battery; ‘LOBAT’ signal
indicates need for replacement.
On/off sliding switch.
0.01 A for 0 to 10 A or
0.01 V for 0 to 20 V.
Dimensions
h 70 mm d 115 mm w 90 mm.
Robustness
Solid black-plastic case; smooth
corners but slightly sharp edge
at junction of base. 3 rubber
feet on base. Reasonably
robust.
4 mm inset at side of case
Red and black; +/- shown on
casing.
Four inset Philips head screws
on the base to access battery
compartment, making it fairly
difficult for pupils.
-
Terminals
Polarity indication
Access
Comments
Ranges available and prices
Ammeters & Voltmeters
Ranges
Ammeter 0 - 10 A
Voltmeter 0 - 19.99 V
Griffin Educational
EHA- 200-030A
EHB- 250-020E
£41.90
£41.90
EMA-020010
EMV-020010
£38.10
£38.10
Scientific & Chemical
Ammeters also available for ranges 0 to 2 A, 0 to 200 mA, and 0 to 200 microamps; Voltmeters
also available for 0 to 2 V range.
20
7.4
Dual function, multi-range digital meters:
features examined and reported
7.4.1 Digital Unilab multi-purpose Easy Read meter for Harris
Suppliers
Display
Battery
On/off
Resolution
Philip Harris.
3 ½ digit liquid crystal.
9 V PP3 battery; ‘LOBAT’ signal
indicates need for replacement.
Battery only on when shunt or
multiplier is in place.
On/off by insertion of shunt.
0.01 A for 0 to 10 A or
0.01 V for 0 to 20 V.
Dimensions
h 73 mm d 65 mm w 96 mm
without shunt.
h 73 mm d 108 mm w 104 mm
with shunt.
Robustness
Terminals
Polarity indication
Access
Comments
Solid orange-plastic case;
sharply angled corners. Metal
plate on back & base. Robust.
4 mm inset at side of case.
Shown on shunt or multiplier.
Two small, inset, Philips head screws on the base to access battery
compartment, making it fairly difficult for pupils.
Shunts and multipliers all fit snugly. Although the meter is quite expensive
and there is an added cost for each shunt etc, the meter has multiple usage
for a variety of situations.
Ranges available and prices
Ammeter / Voltmeter
Ranges
Easy Read meter
Philip Harris
B8H 79933
£46.97
Current shunts and voltage multipliers for standard dc ranges cost about £10 each. Shunts for
milliamp and ac ranges are more expensive.
21
7.5
Multimeters, analogue:
features examined and reported
Multimeters are available for a range of purposes in the home, in industry and
commerce and in schools. Analogue multimeters can normally be used to measure
ranges of dc and ac currents, dc voltages, resistance and most offer other facilities as
well. They typically have at least three sets of scales and are often designed as pocketsized units. Deciding which measurement setting to employ, which scale to use and to
take accurate measurements proves very difficult for younger and for lower-ability
pupils. If they are used as ammeters or voltmeters for Years 7 and 8, then it would be
prudent to have the range switch set by a technician or teacher and probably covered,
although this does not overcome the problem of which scale to read.
Features reviewed are shown below.
Suspension
The suspension is either pivoted, ie, the moving coil is supported between points turning in fixed cups, or taut band, ie,
it is supported between two phosphor-bronze strips. Taut-band
meters should stand up better to school use but are lessfrequently available.
Range of the meter Multimeters will usually cover a range of possible measurement options including:
dc current (often including microamp ranges up to about 10 A)
dc voltage (often from millivolt ranges up to 500 V or more)
ac voltage (say 10 to 500 V)
ac current on some models
resistance (say ×1 ohm to ×1 kohm)
AF output (dB)
capacitance (µF)
Battery & lowbattery indication
Note is made of which battery is used and the means of
indicating when the battery strength is low.
Uncertainty
Only commented on if the claimed maximum uncertainty is
greater than 2%.
Scale length
As before, this is measured as the length of arc through the
midpoints of the smallest divisions of the outer scale.
Dimensions
Indicated in the table.
Zero adjustment
The percentage of the scale length it covers. The greater it is,
the more likely that deviations caused by abuse can be
corrected.
Most have a plastic screw. Comment is made on whether the
adjustment screw is too prominent and easy to turn, so making
it easier for pupils to fiddle.
Robustness
Comment is made on the material of the case and its design,
the presence of sharp corners, etc, and on the ability of the
movement to withstand mechanical shock; analogue meters
were subjected to drop tests.
Mechanical stability. All were found to be stable.
Terminals
Usually three 4 mm jack sockets including one black COM and
two red (typically one for 10 A and one for V / ohm / mA)
Polarity indication Almost all have red and black terminals; some have + and - signs
as well.
22
Access
Comment is made on how easy it is for pupils to reach and
damage components, how easy it is for a repairer to reach
components and to replace the battery and fuse.
Repairability
To replace damaged coils and hairsprings probably costs more
than the price of a replacement meter and so is not usually
worthwhile. However, some manufacturers will make a moderate charge for minor repairs and adjustments, replacing
covers, etc. It may be worth asking for a quotation.
See Section 9 of this guide and Laboratory Handbook section
10.3.4 for further advice on repair including d-i-y repair.
Comments
All come with a pair of leads often with retractable protective
sleeves. Other significant features are mentioned including the
ranges which the meter covers. Generally analogue multimeters
are not recommended for lower-school use because there are
multiple scales and they are often not easy to read.
Prices
What the supplier offers, catalogue numbers, prices.
23
7.5.1
Draper pocket multimeter AMM1
Suppliers
Suspension
Range of meter
Battery
Uncertainty
Scale length
Scientific & Chemical.
Moving coil.
See below.
AA 1.5 V battery;
Low battery signal indicates
need for replacement.
5% for most scales.
37 mm.
Dimensions
h 33 mm d 100 mm w 63 mm.
Zero adjustment
9 % positive movement of
plastic screw.
Light plastic case. Smooth
corners. Sufficiently robust.
Only two 4 mm jack sockets.
Red & black coded and ‘+’ and
‘-‘ signs shown.
Single small, inset screw rear
access to battery compartment,
making it fairly difficult for
pupils.
Parallax mirror. Fuse and diode protected. Leads have unprotected ends.
Very small divisions make it difficult to read accurately. Very compact but
limited current range, multiplicity of scales and difficulty in reading probably
make it unsuitable for lower school use in particular.
Ranges include:
dc current 500 microamps, 10 mA, 250 mA,
dc voltage 2.5 V, 10 V, 50 V, 250 V, 500 V,
ac voltage 10 V, 50 V, 250 V, 500 V
resistance ×10 ohm, ×1 kohm.
Robustness
Terminals
Polarity indication
Access
Comments
Prices
Multimeter
Ranges
Draper analogue Pocket multimeter AMM1
Scientific & Chemical
EMM 310010
£7.20
24
7.5.2
Rapid analogue multimeter 105 DMM
Suppliers
Suspension
Range of meter
Battery
Uncertainty
Scale length
Granet, Rapid.
Moving coil.
See below.
Two AA 1.5 batteries;
battery check facility.
3% for most scales.
55 mm.
Dimensions
h 46 mm d 145 mm w 73 mm.
Zero adjustment
9% positive, movement of
plastic screw.
Solidly built plastic case with
yellow outer casing. Smooth
corners. Robust.
Three 4 mm jack sockets.
Red & black coded but not
signed.
Two inset screws protect rear
access to battery compartment,
making it fairly difficult for
pupils.
Robustness
Terminals
Polarity indication
Access
Comments
500 mA / 250 V fuse and diode protected. Leads have protected ends. Well
built and very cheap but multiplicity of scales and small scale divisions
probably make it less suitable for lower school use in particular.
Features include:
audible continuity test.
Ranges include:
dc current 50 microamps, 5 mA, 500 mA, 10 A,
dc voltage 2.5 V, 10 V, 50 V, 250 V, 500 V,
ac voltage 10 V, 50 V, 250 V, 500 V,
resistance ×1 ohm, ×10 ohm, ×100 ohm, ×1 kohm
AF output -10 to +56 dB,
capacitance 0 to 250 µF.
Prices
Multimeter
Ranges
Draper analogue Pocket multimeter AMM1
Granet
L412000
£8.60
Rapid
85-0722
£4.55
25
7.6
Multimeters, digital (DMMs): features examined and reported
There has been a rapid expansion in the range of digital multimeters available to
school and other buyers in recent years. They cost considerably less than singlefunction digital meters. As with analogue multimeters, if they are used as ammeters
or voltmeters with Years 7 and 8, then it would be helpful to have the range switch
set by a technician or teacher and perhaps covered with a suitable piece of card, or
even hardboard. Such a cover will not be pupil-proof but it would be time-consuming
to make something more elaborate and it is necessary to be able to remove the cover
easily to switch the meter on and off.
If there is a choice, it may be better to use digital multimeters as voltmeters, since
there is then less chance of the fuse in the meter being blown.
General advice on digital multimeters is given in section 12.3 of the Laboratory
Handbook. The market has become highly competitive. They often are alike but have
different trade names or look alike but have slightly different features. If meters are
being purchased to be used as ammeters or voltmeters for Key Stages 3 and 4, choices
are not easy. However, some digital multimeters do not have the 10 A current range
essential for work involving heating and magnetic effects. Apart from this, buyers
should choose a low-price meter with a rotary switch. Opinions will vary on the
suitability for pupils of autoranging, the facility of the meter to select the right range.
CLEAPSS believes that, where pupils are sufficiently able, there is value in the pupil
learning to select the correct range so that a non-autoranging model should be chosen.
However, if DMMs are to be used in the sixth form, schools are advised to look closely
at the ranges, particularly if electronics is taught and to look for suitable low-current
ranges. The following observations may help schools to make judgements.
dc volts
Many digital multimeters have the following ranges: 200 mV, 2, 20, 200 and 1000 V.
One or two lack the 200 mV range. The resolution on the 2 V range is 1 mV so that
the omission of the 200 mV range may not matter. However, it would be difficult to
measure the emf of a thermocouple without this range.
dc current
What is available varies much more. Several have the following ranges: 200 µA, 2, 20,
200 mA, 2, 10 A; however, some have only three or two current ranges. Both 2 mA and
10 A ranges are desirable, with at least one intermediate range. The high resolution of
the multimeter enables reasonably-accurate readings to be made of quantities only a
tenth of the range maximum so that many intermediate ranges may not be necessary.
ac ranges
Again, these vary from model to model. They often correspond to the dc ranges, with
one or two omissions, but some DMMs have no ac current ranges. Some digital
multimeters with several ac ranges are needed for work on transformers and it might
be useful to be able to measure alternating current powering a heating coil: both
20 mA and 10 A ranges are useful. However, most school work is with dc so that
limited ac ranges may not matter for most of the meters to be used by a class.
Resistance
The following ranges are standard: 200 Ω, 2, 20, 200 kΩ, 2 MΩ. Several have an
additional 20 MΩ range, some a 20 Ω range. While the 20 MΩ range is valuable for
electronics, a 20 Ω range is more useful for general work.
Other facilities
DMMs frequently have other facilities, for example, for testing continuity, diodes and
transistors, for measuring capacitance etc. With the possible exceptions of continuity
testing and ‘hold’, these facilities are an additional complication during general use
and so are to be avoided if possible. They may be of use during electronics work.
26
What pupils see can be simplified if the front of the meter is covered. The cover should
conceal any sockets which should not be used as well as the switch and associated
information. If necessary, holes could be drilled over the sockets to be used.
A selection of lower-priced digital multimeters is reviewed. Features included are
shown below.
Display
3 ½ digit liquid-crystal display is the most common with a
nominal height of 0.5" (12 - 13 mm). 3 ½ means that the
maximum reading (omitting the decimal point) is 1999, so ‘4 ½’
means 19999 etc. Thus readings on a 20 V scale would be from
0.00 to 19.99 V.
Battery & low battery indication
A variety of battery types is used. Most have some means of
indicating when the battery strength is low, eg, by a flashing
'LOW BATT' sign. In some of the models the highest current
circuit is not fused.
On/off switch
Almost all have on/off switches.
Dimensions
Indicated in the table.
Resolution
Indicates level of accuracy.
Robustness
Comment is made on the material of the case and its design,
the presence of sharp corners etc.
Terminals
Usually three 4 mm jack sockets including one black COM and
two red (typically one for 10 A and one for V / ohm / mA)
Polarity indication Almost all have red and black terminals; some have + and - signs
as well. A negative sign in front of the display indicates reversed
connections.
Access
Comment is made on how easy it is for pupils to reach and
damage components, how easy it is for a repairer to reach
components and to replace the battery and fuse.
Repairability
See Section 9 of this guide and Laboratory Handbook section
10.3.4 for further advice on repair, including d-i-y repair.
Comments
All come with a pair of leads often with retractable protective
sleeves. Other significant features are mentioned including the
ranges which the meter covers. Digital multimeters do not suffer
from the scale-reading problems as analogue multimeters but
still suffer from the potential problem of a wide range of possible
range settings (see suggestion above).
Prices
What the suppliers offer, catalogue numbers, prices.
27
7.6.1
JPR UNI-T UT20B digital pocket multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
JPR.
3 ½ digit liquid crystal.
12 V A23 battery; appearance
of battery symbol indicates
need for replacement. 0.2 A,
250 V fuse.
Rotating switch for scale
selection and on/off.
h 26 mm d 90 mm w 52 mm.
Compact red-plastic case;
smooth corners.
Test leads fixed to side of
casing.
Test leads colour coded.
Guidance booklet indicated that there should be a screw access to the
battery compartment on the base but none was apparent on the model
tested.
Features include:
diode test.
Ranges include:
dc current 2000 microamps, 20 mA, 200 mA,
dc voltage 200 mV, 2000 mV, 20 V, 200 V, 300 V,
ac voltage 200 V, 300 V,
resistance ×200 ohm to ×2000 kohm.
This is an extremely-low price model but has limited dc current ranges in
particular but if found to be useful by schools could be considered as
disposable.
Prices
Range
Multimeter UNI-T UT20B
JPR
375-405
£3.95
28
7.6.2
Rapid 212 digital pocket multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Granet, Philip Harris, Rapid.
3 ½ digit liquid crystal.
9 V PP3 battery; appearance of
battery symbol indicates need
for replacement. 250 mA, 250 V
fuse.
Rotating switch for scale
selection and on/off.
h 25 mm d 125 mm w 70 mm
Neat black-plastic case; smooth
corners.
3 jack sockets for 4 mm plugs:
COM, 10 A (fused) and
v / ohm / mA.
No colour coding or use of +/signs.
Two Philips head screws,
deeply set in the base, making
pupil access difficult. Easy for
battery and fuse replacement.
Connecting leads have protected ends.
Features include:
diode test,
transistor test.
Ranges include:
dc current 200 microamps, 2000 microamps, 20 mA, 200 mA, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 600 V,
ac voltage 200 V, 600 V,
resistance ×200 ohm to ×2000 kohm.
This is a competitively low price model and could be useful to schools opting
for class sets of digital multimeters.
Prices
Range
Pocket Multimeter 212
Granet
L412030
£13.00
Philip Harris
B8L26852
£11.16
Rapid
85-0622
£5.50
29
7.6.3
Ravencourt SATZ UT 30B digital multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Ravencourt, Timstar.
3 ½ digit liquid crystal.
9 V PP3 battery; the
appearance a of battery symbol
indicates need for replacement.
05 x 20 - 315 mA, 250 V fuse.
Rotating switch for scale
selection and on/off.
h 30 mm d 128 mm w 72 mm.
Gold-coloured plastic case;
smooth corners. 2 small rubber
feet.
3 jack sockets for 4 mm plugs:
COM, 10 A (fused) and
v / ohm / mA.
Sockets colour coded with a
small orange/red and black
mark which is not immediately
obvious. There is no + or polarity indication.
Removal of rubber feet gives
access to two small Philips head
screws inset on the base - pupil
access is difficult. Screws are
very small but battery and fuse
replacement are not very
difficult.
Features include:
data HOLD function via button in centre of dial,
diode test,
transistor test.
Ranges include:
dc current 200 microamps, 2 mA, 20 mA, 200 mA,10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 500 V,
ac current 200 mA, 10 A,
ac voltage similar range to dc voltage though with less accuracy,
resistance ×200 ohm to ×20 Mohm.
This is another competitively priced model and could be useful to schools
opting for class sets of digital multimeters.
Prices
Range
SATZ UT30B
Ravencourt
Palmsize UT30B
£7.70
Timstar
EL52410
£7.70
30
7.6.4
Economatics Skytronic digital multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Economatics.
3 ½ digit liquid crystal.
9 V PP3 battery; Appearance of
a battery symbol indicates need
for replacement. 200 mA, 250 V
fuse.
Rotating switch for scale
selection and on/off.
h 28 mm d 125 mm w 70 mm.
Plastic case; smooth corners.
3 jack sockets for 4 mm plugs:
COM, 10 A (fused) and
v / ohm / mA.
Sockets colour coded.
Two Philips head screws deeply
set in the base, making pupil
access difficult. Easy for battery
and fuse replacement by adults.
Lead ends are not protected.
Features include:
diode test,
transistor test.
Ranges include:
dc current 200 microamps, 2000 microamps, 20 mA, 200 mA,10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 1000 V,
ac voltage 200 V, 750 V,
resistance ×200 ohm to ×2000 kohm.
This is also a competitively low-price model. However, there was screen
fade on the model tested although this problem was not commented on by
schools nor has it been reported to the suppliers. If it is not a problem this
model could be useful to schools opting for class sets of digital multimeters.
Prices
Range
Economatics Skytronic
Economatics
600.032 RB 5328
£8.95
31
7.6.5
Rapid 318 digital multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Granet, Rapid.
3 ½ digit liquid crystal.
9 V PP3 battery; appearance of
battery symbol indicates need
for replacement. 300 mA, 250 V
fuse.
Rotating switch for scale
selection and on/off.
h 46 mm d 200 mm w 97 mm.
Solid black plastic-case; smooth
corners. Substantial rubber
outer case.
4 jack sockets for 4 mm plugs:
COM, 10 A, A and v / ohm.
Sockets colour coded.
Single inset Philips head
screws on the base, making
pupil access difficult. Easy for
battery and fuse replacement.
Features include:
audible continuity test,
diode test,
transistor test.
Ranges include:
dc current 20 and 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 10 A,
ac current 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 1000 V,
ac voltage 200 mV, 2 V, 20 V, 200 V, 700 V,
resistance ×200 ohm to ×200 Mohm.
This is a competitively low-price model with a wider range of functions than
some other low priced models and could be useful to schools opting for
class sets of digital multimeters.
Prices
Range
Rapid 318 Multimeter
Granet
L412060
£20.53
Rapid
85-0719
£9.90
32
7.6.6
CALTEK CM2400-T digital multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
The Consortium, JPR.
3 ½ digit liquid crystal.
9 V PP3 battery; Low-battery
signal indicates need for
replacement. 200 mA, 250 V
fast fuse.
Rotating switch for scale
selection and on/off.
h 27 mm d 125 mm w 68 mm.
Solid yellow-plastic case;
smooth corners.
3 jack sockets for 4 mm plugs:
COM, 10 A, and v / ohm / mA.
No colour coding but printing on
case.
Two Philips head screws,
deeply set in the base, making
pupil access difficult. Easy for
battery and fuse replacement.
Leads have protected ends.
Features include:
audible continuity test,
diode test,
transistor test,
temperature measurement.
Ranges include:
dc current 200 microamps, 2 mA, 20 mA, 200 mA, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 600 V,
ac voltage 200 V, 600 V,
resistance ×200 ohm to ×2000 kohm.
Automatic zero adjustment. This is another low-price model with an
adequate range of functions.
Prices
Range
CALTEK CM2400-T
The Consortium
055787
£12.55
JPR
375-482
£10.50
33
7.6.7
jtw DM-830D+
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Scientific & Chemical.
3 ½ digit liquid crystal.
9 V PP3 battery; ‘BAT’ symbol
indicates need for battery
replacement. 200 mA, 250 V
fuse.
Rotating switch for scale
selection and on/off.
h 27 mm d 135 mm w 78 mm.
Solid black-plastic case,
enclosed in orange-rubber
protective case; smooth
corners.
3 jack sockets for 4 mm plugs:
COM, 10 A, and v / ohm / mA.
Colour coding shows polarity
but no + or - sign.
Two Philips head screws, inset
on the base, making pupil
access difficult. Easy for battery
and fuse replacement.
Features include:
audible continuity test,
diode test,
transistor test,
temperature measurement.
Ranges include:
dc current 200 microamps, 2 mA, 20 mA, 200 mA, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 1000 V,
ac voltage 200 V, 750 V,
resistance ×200 ohm to ×2000 kohm.
This is another low-price model with an adequate range of functions.
Prices
Range
jtw DM-830 D+
Scientific & Chemical
EMM 040010
£10.91
34
7.6.8
Draper DMM 1A
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Scientific & Chemical.
3 ½ digit liquid crystal.
9 V PP3 battery; Appearance of
battery symbol indicates need
for replacement. 250 mA, 250 V
fuse.
Rotating switch for scale
selection and on/off.
h 50 mm d 140 mm w 64 mm.
Solid blue-plastic case enclosed
in blue-rubber jacket; smooth
corners.
3 jack sockets for 4 mm plugs:
COM, 10 A, and v / ohm / mA.
No colour coding or + or – signs
to indicate polarity.
Single Philips head screw, inset
on the base, making pupil
access difficult. Easy for battery
and fuse replacement.
Integral support attached to back of instrument. Lead ends protected.
Features include:
audible continuity test,
data HOLD function,
diode test,
transistor test.
Ranges include:
dc current 2000 microamps, 20 mA, 200 mA, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 600 V,
ac voltage 200 V, 600 V,
resistance ×200 ohm to ×2000 kohm,
This is another fairly low-price model with an adequate range of functions.
Prices
Range
Draper DMM 1A
Scientific & Chemical
EMM 010010
£14.77
35
7.6.9
UNI-T UT39A
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Commotion.
3 ½ digit liquid crystal.
9 V PP3 battery; Appearance of
battery symbol indicates need
for replacement. 315 mA, 250 V
fast fuse.
Power on/off button.
h 40 mm d 160 mm w 84 mm.
Solid black-plastic case
enclosed in red-rubber
protective jacket; smooth
corners.
4 jack sockets for 4 mm plugs:
COM, 10 A, microamp / mA and
v / ohm.
No colour coding.
Single Philips head screw, inset
on the base, making pupil
access difficult. Easy for battery
and fuse replacement.
Features include:
audible continuity test,
capacitance measurement,
data HOLD facility via blue button,
diode test,
transistor test.
Ranges include:
dc current 20 microamps, 200 microamps, 2 mA, 20 mA, 200 mA, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 1000 V,
ac current 200 microamps, 20 mA, 200 mA, 10 A,
ac voltage 2 V, 20 V, 200 V, 750 V,
resistance ×200 ohm to ×2000 Mohm.
Leads do not have protected ends. Screen shows data hold operating and
dangerous voltages. Auto-disconnect if not used for 15 minutes. Rear has
bracket for upright standing. This model has a wider range of functions
should they be needed, at what is still a reasonable price.
Prices
Range
UNI-T 39A
Commotion
27037
£17.50
36
7.6.10
SATZ UT51
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Ravencourt, Timstar.
3 ½ digit liquid crystal.
9 V PP3 battery; appearance of
battery symbol indicates need
for replacement. 2 A, 250 V and
10 A 250 V fuses.
Power on/off switch.
h 50 mm d 200 mm w 95 mm.
Very solid black-plastic case
enclosed in black-rubber
protective jacket; smooth
corners.
4 jack sockets for 4 mm plugs:
COM, 10 A, A and v / ohm.
Red and black colour coding.
Single Philips head screw, inset
on the base, making pupil
access difficult. Easy for battery
and fuse replacement.
Features include:
audible continuity test,
capacitance measurement,
diode test,
transistor test.
Ranges include:
dc current 20 and 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 10 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 1000 V,
ac current 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 10 A,
ac voltage 200 mV, 2 V, 20 V, 200 V, 750 V,
resistance ×200 ohm to ×2000 Mohm.
Bracket for upright standing and holster provided. This model again has a
wider range of functions, should they be needed, at what is still a
reasonable price.
Price
Range
SATZ UT 51
Ravencourt
SATZ UT51
£19.95
Timstar
EL52415
£19.95
37
7.6.11
CALTEK CM3900A
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Commotion.
3 ½ digit liquid crystal.
9 V PP3 battery; appearance of
battery symbol indicates need
for replacement. 2 A, 250 V fast
fuse.
Power on/off button.
h 46 mm d 170 mm w 85 mm.
Solid orange / yellow-plastic
case; smooth corners.
4 jack sockets for 4 mm plugs:
COM, 20 A, micro / mA and
v / ohm.
Red and black colour coding
and named.
Single Philips head screw, inset
on the base, making pupil
access difficult. Easy for battery
and fuse replacement by adults.
Two deep set larger Philips
head screws protect access to
the circuits.
Leads ends protected.
Features include:
audible continuity test,
diode test,
transistor test.
Ranges include:
dc current 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 20 A,
dc voltage 200 mV, 2 V, 20 V, 200 V, 600 V,
ac current 200 microamps, 2 mA, 20 mA, 200 mA, 2 A, 20 A,
ac voltage 200 mV, 2 V, 20 V, 200 V, 600 V,
resistance ×200 ohm to ×20 Mohm.
Screen indicates units as well as value. Bracket for upright standing
provided. Automatic power off after 15 minutes. This model again has a
slightly wider range of functions, should they be needed, though the price is
a little higher.
Price
Range
CALTEK CM3900A
Commotion
27027
£25.00
JPR
375-475
£14.95
38
7.6.12
UNI-T UT60A digital multimeter
Suppliers
Suspension
Battery/fuse
On/off
Dimensions
Robustness
Terminals
Polarity indication
Access
Comments
Philip Harris.
3 ½ digit liquid crystal.
9 V PP3 battery; appearance of
battery symbol indicates need
for replacement. 0.5 A, 250 V
and 10 A, 250 V fast fuses.
Orange on/off power switch.
Blue switch enables rapid
change between dc and ac.
h 40 mm d 175 mm w 85 mm.
Red rubberised case; smooth
corners.
Four 4 mm jack sockets COM,
10 A, micro / mA and Hz / v / ohm.
Not colour coded or marked +
or -.
Single Philips screw protects
access to the battery compartment on the base and two
screws protect access to the
circuits.
Auto-ranger selects best range for greatest resolution. Instrument has a
RS232c standard serial port, interface cable and software to enable
connection to a computer for data capture. Lead ends unprotected. Integral
support for upright usage included.
Features include:
audible continuity test,
capacitance measurement,
data HOLD facility,
diode test,
frequency test.
Ranges include:
dc current 400 microamps, 4000 microamps, 40 mA, 400 mA, 4 A, 10 A,
ac current 400 microamps, 4000 microamps, 40 mA, 400 mA, 4 A, 10 A,
dc voltage 400 mV, 4 V, 40 V, 400 V, 1000 V,
ac voltage 4 V, 40 V, 400 V, 750 V,
resistance ×400 ohm to ×40 Mohm.
This is a more-expensive model but the extra facilities including computer
linkage potential may make it of interest to some schools.
Price
Range
UNI-T UT60A
Maplin
N80CB
£29.99
Philip Harris
B8L 16652
£36.50
39
8.
Galvanometers
Whilst this guide deals mainly with ammeters and voltmeters for pupil use, it is
worth mentioning galvanometers which can also be used by pupils. As noted in
Section 4, Table 5, galvanometers are moving-coil, electric-current detectors mainly
used as devices which can measure the magnitude and direction of very small electric
currents. They may be used, for example, to detect a null or unbalanced condition in a
bridge or potentiometer circuit. Only a small proportion of schools’ suppliers include
the traditional centre-zero galvanometers for pupil use in their catalogues but, for
many purposes, some of the analogue ammeters described in section 7.1, in which the
scale starts at a minus number, could be used for this purpose. More suppliers sell
demonstration galvanometers but these are much more expensive and are outside the
scope of this guide. Table 6 gives an outline of some of the pupil models currently on
the market. No further tests were carried out on these models.
Table 6
Pupil galvanometers available
Moving coil - centre zero
Suppliers
Range
Catalogue Number
Price
ASCOL
-35 mV - 0 - 35 mV
P59 1100ELO 4901
£8.53
Beecroft (STE)
-35 mV - 0 - 35 mV
ELO 4901
£28.66
Griffin Education (STE)
-35 mV - 0 - 35 mV
EHG-250-100c
£24.40
Philip Harris
-3.5 mA - 0 - 3.5 mA
B8A 74731
£33.55
Philip Harris
-50 microA - 0 - 50 microA B8A 74729
£36.12
9.
Repairs to meters
General guidance is given in Laboratory Handbook section 10.3.4. On the whole it is
advisable for school staff only to undertake simple external repairs to analogue (and
digital) meters such as tightening terminals. This is because any attempt to repair
internal faults will invalidate any warranty. Little maintenance is possible on digital
meters, other than replacement of the battery, in any case.
Many schools tend to be restricted by finances to cheaper meters. When a meter is
faulty and is within the warranty period, the supplier should be contacted and should
provide a replacement free of charge. Nowadays, it is often as costly for a supplier to
repair a meter as to replace it. So, if a cheaper meter is outside its warranty period,
schools may well be advised to replace the meter, especially since it is easy to forget to
include the cost of postage and packing in each direction in calculating costs.
Each supplier has its own approach to repair of meters. Table 7 gives information
received from suppliers and manufacturers. Some do not undertake repairs at all,
others will including some who use a linked repair company. Schools are advised to
seek advice about repair and replacement from the supplier before meters are
purchased. It is usually worth asking for a quote if there is not a standard price for
repairs.
40
Table 7
Repair information
Supplier/manufacturer
Repair service offered other than warranty replacement
Beecroft
None
Commotion
None
Economatics
None
Granet
None
Griffin Education / Fisher
None
JPR
None
Philip Harris / Findel
Charged service provided by Techlab
Ravencourt
Charged service provided
Scientific & Chemical
None though it might consider a large batch of repairs.
Timstar
Charged service provided
P&B Weir
Charged service provided
10.
Disposal of electrical meters and other electrical equipment
10.1 The WEEE regulations
The Waste Electrical and Electronic Equipment (WEEE) Regulations 2006 are
intended to reduce the amount of waste electrical and electronic equipment which is
currently being disposed of in landfill sites. The intention is to encourage separate
collection and, as far as possible, treatment and recycling.
Most of the provisions came into force on 1st July 2007. They make producers of new
equipment responsible for paying for the treatment or recycling of products at the end
of their useful life. This will affect all businesses which manufacture, brand, import,
sell, store or dismantle such equipment. Distributors and retailers will be responsible
for taking back WEEE in a way convenient to customers (including schools and
colleges) and free of charge. This may ultimately be reflected in purchase costs once
the Regulations have been in operation for sufficient time to assess their impact.
The Regulations apply to all electrical and electronic equipment whether used in
domestic, educational or commercial situations. Thus, items such as refrigerators,
radios, lighting equipment, computers and medical equipment will be covered. It
follows that, in schools, all such equipment and not solely that used in science
departments, will be covered by the Regulations. These kinds of equipment will, in
future, carry the RECYCLE, DO NOT DISCARD symbol.
It will take some time for suppliers and manufacturers to finalise and implement
their systems for meeting the new requirements. These may involve different
approaches according to the nature of the equipment and to the area of the country in
which they are located. Schools, domestic and other users of electrical equipment are
not obliged to take advantage of the collection approaches offered but will need to
make alternative arrangements that also meet the requirements, if they choose not to.
Schools will also need to be able to identify where electrical equipment was purchased
when it ultimately comes to disposal, so would be advised to keep copies of invoices or
delivery notes to help them.
Different arrangements will apply for products put on the market before 13 August
2005. If the school is replacing such electrical equipment, the new “producer” will be
responsible for financing the collection, recycling and disposal of old equipment (even
if a different make is being purchased). If the equipment is not being replaced then
responsibility falls on the school (or business) to dispose of the equipment in
accordance with the Regulations.
Further information is given in CLEAPSS position statement PS75.
41
10.2 Responses of manufacturers and distributors to the WEEE regulations
At the time of updating this guide (July 2007), there was a wide range of different
responses from suppliers of meters about how they would meet the WEEE requirements. Some had clearly given a good deal of thought to the matter and had linked
with a compliance scheme for reporting on, collection and treatment of all WEEE
produce for which the company had responsibility. Others were proposing to offer to
schools disposal of WEEE which they returned but were clearly anticipating that
many schools would undertake responsibility for disposal of broken waste electrical
items themselves. A few had not, at that stage, really devised any facility at all and
were only starting to give the matter some thought.
A small number of companies had not fully appreciated the extent of their
responsibilities and were at that time indicating that they believed that they would
not carry any liability where they bought in products from other UK or EU companies
and manufacturers for resale. Equally a few manufacturers believed that the liability
lay with the suppliers.
Clearly the situation will change as companies appreciate more fully the extent of
their responsibilities and have had some experience of the scale of the problem.
Nevertheless, schools are advised to check the approach of the relevant company at
the time of any proposed purchase.
42
Appendix 1 Manufacturers’ and suppliers’ addresses
ASCOL
PO Box 6745
Beeston, Nottingham
NG9 6QN
Tel:
0115 9256049
Fax:
0115 9254511
Email: sales@ascol.co.uk
Web site: www.ascol.co.uk
GLS Fairway
1 Mollison Avenue
Enfield
EN3 7XQ
Tel:
0845 1203213
Fax:
0800 9172246
Email: sales@glsed.co.uk
Web site: www.glsed.co.uk
Beecroft & Partners Ltd
Northfield Road
Rotherham, South Yorkshire
S60 1RR
Tel:
01709 377881
Fax:
01709 369264
Email: sales@beecroft-science.co.uk
Web site: www.beecroft-science.co.uk
Granet
PO Box 404,
Aylesbury, Buckinghamshire
HP19 9WD
Tel:
01296 398624
Fax:
01296 426507
Email: sales@granetscience.co.uk
Web site: www.granetscience.co.uk
IP Chambers Electronics
Holker School
Cark-in-Cartmel
Grange-over-Sands, Cumbria
LA11 7PQ
Tel:
015395 58555
Fax:
015395 58558
Email: mail@ipcel.co.uk
Web site: www.ipcel.co.uk
Griffin Education
Bishop Meadow Road
Loughborough
LE11 5RG
Tel:
01509 233344
Fax:
01509 555200
Email: griffin@fisher.co.uk
Web site: www.griffineducation.co.uk
Commotion Group
Commotion House
Morley Road
Tonbridge, Kent
TN9 1RA
Tel:
01732 773399
Fax:
01732 773390
Email: sales@commotiongroup.co.uk
Web site: www.commotiongroup.co.uk
Fisher Scientific
Bishop Meadow Road
Loughborough
LE11 5RG
Tel:
01509 231166
Fax:
01509 231893
Email: sales@fisher.co.uk
Web site: www.fisher.co.uk
(Order Fisher products via
Griffin Education)
The Consortium
Hammond Way
Trowbridge
Wiltshire
BA14 8RR
Tel:
0845 3307780
Fax:
0845 3307785
Email: enquiries@theconsortium.co.uk
Web site: www.theconsortium.co.uk
Philip Harris Ltd
Hyde Buildings
Hyde
Cheshire
SK14 4SH
Tel:
0845 1204520
Fax:
0800 1388881
Email: customerservice@philipharris.co.uk
Web site: www.philipharris.co.uk
Economatics
19b Orgreave Close
Handsworth, Sheffield
S13 9NP
Tel:
0114 2813311
Fax:
01114 269740
Email: sales@economatics.co.uk
Web site: www.economatics.co.uk
JPR Electronics
4 Circle Business Centre
Dunstable, Bedfordshire
LU5 5DP
Tel:
01582 470000
Fax:
01582 470001
Email: sales@jprelec.co.uk
Web site: www.jprelec.co.uk
43
Maplin Electronics Ltd
PO Box 777
Valley Road, Wombwell
Barnsley, Yorkshire
S73 0BS
Tel:
0870 4296000
Fax:
0870 4296001
Email: customerservice@maplin.co.uk
Web site: www.maplin.co.uk
Timstar Laboratory Suppliers Ltd
Timstar House
Marshfield Bank, Herald Drive
Crewe, Cheshire
CW2 8UY
Tel:
01270 250459
Fax:
01270 250601
Email: sales@timstar.co.uk
Web site: www.timstar.co.uk
Optical Vision Ltd
Unit 2b, Woolpit Business Park
Woolpit, Bury St Edmunds
Suffolk
IP30 9UP
Tel:
01359 244200
Fax:
01359 244255
Email: info@opticalvision.co.uk
Web site: www.opticalvision.co.uk
Unilab (See Philip Harris for details)
Hyde Buildings
Hyde,
Cheshire,
SK14 4SH
Tel:
0845 1204520
Fax:
0800 1388881
Email: enquiries@philipharris.co.uk
Web site: www.unilab.co.uk
Rapid Electronics
Severalls Lane
Colchester
Essex
CO4 5JS
Tel:
01206 751166
Fax:
01206 751188
Email: sales@rapidelec.co.uk
Web site: www.rapidonline.co.uk
P & B Weir Electrical
Unit 10
Leafield Trading Estate
Corsham
SN13 9SW
Tel:
01225 811449
Fax:
01225 810909
Email: sales@pbweir.co.uk
Web site: www.pbweir.co.uk
Ravencourt Ltd
Drift Road
Stamford, Lincolnshire
Woolpit Business Park
PE9 1UT
Tel:
01780 489100
Fax:
01780 489099
Email: sales@ravencourt.com
Web site: www.ravencourt.com
Yorkshire Purchasing Organisation
(YPO)
41 Industrial Park
Wakefield, Yorkshire
WF2 0XE
Tel:
01924 824477
Fax:
01924 834805
Email: sales@ypo.co.uk
Web site: www.ypo.co.uk
Scientific & Chemical Supplies
Carlton House,
Livingstone Road
Bilston
WV14 0QZ
Tel:
01902 402402
Fax:
01902 402434
Email: info@scichem.com
Web site: www.scichem.com
STE UK Ltd
Staplehurst Road
Sittingbourne, Kent
ME10 2NH
Tel:
01795 474700
Fax:
01227 200112
Email: sales@steuk.co.uk
Web site: www.steuk.co.uk
44