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Office, Scientific, Vehicle Products, Valves, Microphones, Galvonometers, Test and Measurement

A Short History of the Galvanometer

A Short History of the Galvanometer


Image of RADIOVISOR LIGHT DEPENDANT RESISTOR, 1940's

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RADIOVISOR LIGHT DEPENDANT RESISTOR, 1940's

Light dependant resistor for use in alarm systems or counting in factories.
Resistance of the unit varies with the light shone upon it, so if the light is interrupted the resistance will change.

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A0563

Image of MERCURY  CONTACT RELAY, 1930's

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MERCURY CONTACT RELAY, 1930's

Switching by contacts immersed in Mercury is almost maintenance free, and can carry reasonable currents.

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A0303

Image of P/X VARIABLE CAPACITOR, 1940's

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P/X VARIABLE CAPACITOR, 1940's

Variable capacitor value changed by sliding inner tube outwards, connections are two push wire clamps. Nothing more is known about this item.

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A1532

Image of LAMP AND SWITCH DEMONSTRATION BOARD, 1910's

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LAMP AND SWITCH DEMONSTRATION BOARD, 1910's

Board with 6 X Lamps one dated 1915, 7 X switches and switch sockets, one dated 1926 and 3 X cards of fuse wire.

This board can be demonstrated.

Bruce Hammond Collection

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A1178

Image of CABLE DUCTS AND FIXINGS, 1930's

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CABLE DUCTS AND FIXINGS, 1930's

Various type of cable management including wooden trays or Ducts with covers and Porcelain blocks for running cables on the surface of walls to light switches etc. Also porcelain mountings for meter boards still seen today.

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A1455

Image of WIRELESS ACCUMULATOR, 1940's

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WIRELESS ACCUMULATOR, 1940's

2 Volt accumulator used in wireless sets for the heaters of the valves. It was normally given to the local garage, hardware merchant, or cycle shop for recharging. They would give you your spare unit while this was being done.

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A1237

Image of A SELECTION OF EARLY BATTERIES, 1940's

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A SELECTION OF EARLY BATTERIES, 1940's

Dry batteries and accumulators (item A1237) were common before mains electricity was widely available, batteries continued for portable sets, as they do today. The picture represents some of the large types that were used with domestic wireless receivers from 1940 to 1960. Bottom row left to right. Ever Ready AD3 90V HT and 1.5V LT, Vidormax L5507 90V HT and 1.5V LT, Drydex Red Triangle H1136 with 23 taps providing LT HT and Grid Bias, Top row left to right. Exide H1146 90 Volts only, Ever Ready 762 45 volts only. Exide DM538 90 Volts only, and Ever Ready B126 90 volts only.
A0175 to A0181

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Image of GALENA - LION MICRO CRYSTAL, 1920's

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GALENA - LION MICRO CRYSTAL, 1920's

Replacement crystal for 'Lion' detector. Crystal is Galena or Sulphide of Lead. Marked on the box Refills for the Liontron Detector price 1/6

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A0141

Image of 'MICROLODE' LOUDSPEAKER UNIT, 1933

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'MICROLODE' LOUDSPEAKER UNIT, 1933

Speaker with multiple tapped Transformer for 11 X different impedance settings, which are set by the switch. Seven for single valve output stages, and four ranges for push-pull class 'B' output stages. Shown at The Radio Show Olympia in August 1933.

Donated by John Lay

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A0916

Image of EDISON AND BELL RADIO PLUG IN TUNING COIL, 1920's

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EDISON AND BELL RADIO PLUG IN TUNING COIL, 1920's

Used in the tuning circuit of early wireless receivers and crystal sets for changing the receivable wavelength.

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A0297

Image of CONDENSER BANK WITH KNIFE TUNING SWITCHES, 1920's

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CONDENSER BANK WITH KNIFE TUNING SWITCHES, 1920's

Tapped capacitor with selection by five knife switches marked .5-1-2-4 and 8 Micro farads.Probably used with early transmitters or receivers during WW1.

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A0273

Image of TELEVISION PROJECTOR OPTICS SYSTEM, 1940's

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TELEVISION PROJECTOR OPTICS SYSTEM, 1940's

Used with Philips projector Television, Schmidt Optics system. At the time only the UK and France had television services. This item could produce a picture 4ft x 3ft (1.22m x 0.91m).

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A0116

Image of LIGHTNING CONDUCTOR, 1950's

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LIGHTNING CONDUCTOR, 1950's

Used near Aerial lines but slightly higher, to attract lightning away from the aerial.
A direct strike would not protect very much as the voltage would be high enough not only damage the aerial but also anything in the proximity of the wiring, however a near strike would send all received voltages to ground.
In the case of Sheet lightning whole areas can be ionised causing the atmosphere to glow blue in colour, such strikes are generally dissipated and without the conductor wired to ground certain damage would occur.
The base is for display only.

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A0719

Image of KNIFE SWITCHES, 1940's

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KNIFE SWITCHES, 1940's

A selection of knife switches for general switching purposes.From the 1940's&50's
Single pole lever switches switches were often used to protect wireless units from lightning damage, and were commonly seen on window ledges during the 1950's and before.
Normally the lever is thrown to connect the aerial, when the operator is finished the lever is changed over to the other side, which is connected to earth. A direct strike would not protect very much as the voltage would be high enough not only damage the aerial but also anything in the proximity of the wiring, however a near strike would send all received voltages to ground.
In the case of Sheet lightning whole areas can be ionised causing the atmosphere to glow blue in colour, such strikes are generally dissipated and without the switch being set to ground certain damage would occur.
On some of the switches there is a spark gap in the On position, so that if the switch is not in the earth position some of the voltage can jump the gap.

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A0760-5

Image of EARLY DELAY LINE STC, 1970

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EARLY DELAY LINE STC, 1970

Delay lines are used in colour Television and Videocorders. This is STC's early version dating from 1970, and two later production models to 1978

Nortell Collection

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A1426

Image of GENELEX EARTHING SWITCH, 1940's

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GENELEX EARTHING SWITCH, 1940's

Double pole lever switch, these switches were often used to protect wireless units from lightning damage. Normally the lever is thrown to connect the aerial, when the operator is finished the lever is changed over to the other side, which is connected to earth. A direct strike would not protect very much as the voltage would be high enough not only damage the aerial but also anything in the proximity of the wiring, however a near strike would send all received voltages to ground. In the case of Sheet lightning whole areas can be ionised causing the atmosphere to glow blue in colour, such strikes are generally dissipated and without the switch being set to ground certain damage would occur.

Bruce Hammond Collection

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A1513

Image of TELSEN 4 PIN & 5 PIN VALVE HOLDERS, 1940's

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TELSEN 4 PIN & 5 PIN VALVE HOLDERS, 1940's

Telsen 4 pin and 5 pin Valve holders in original box.

Bruce Hammond Collection

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A1512

Image of SCREWDRIVER IN THE SHAPE OF A 4 PIN VALVE, 1940's

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SCREWDRIVER IN THE SHAPE OF A 4 PIN VALVE, 1940's

A large pocket screwdriver with detachable bits in the shape of a 4 pin valve, and made of Wood and Brass, with Steel bits.

Bruce Hammond Collection

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A1510

Image of ELECTRON INSULATOR PINS, 1940's

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ELECTRON INSULATOR PINS, 1940's

Box of Insulator pins for mounting a Wireless Aerial to the picture rail inside a room, giving an inside version instead of an Aerial outside the house. Signal strength for good reception would need to be good, as with early Wireless receivers were not as sensitive as today’s models.

Bruce Hammond Collection

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A1508

Image of EVER READY AD35 RADIO BATTERY, 1950's

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EVER READY AD35 RADIO BATTERY, 1950's

Battery used in portable Radio's for powering the valve heaters. As long as portable valve receivers were still in use, Purchasing these batteries was possible.


Bruce Hammond Collection

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A1507

Image of DRYDEX TYPE 1001 GRID BIAS BATTERY, 1940's

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DRYDEX TYPE 1001 GRID BIAS BATTERY, 1940's

Grid Bias battery of 9 volts with taps down to 1.5 Volts, In early directly heated valve receivers there was no automatic bias for the valve grid, a battery was used to bias the valves grid negative for the correct operation of the valve.

Bruce Hammond Collection

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A1506

Image of HARLIE TONE SELECTOR, 1940's

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HARLIE TONE SELECTOR, 1940's

Harlie Tone switch presumably for headphones or an extension loudspeaker at each end is a pair of sockets for plugging in and out; the wiring inside passes straight through with a selection of condensers to alter high frequency response.

Bruce Hammond Collection

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A1503

Image of HERTZITE & URALIUM CRYSTALS, 1920's

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HERTZITE & URALIUM CRYSTALS, 1920's

Crystals were used in assemblies for the detection or demodulation of radio waves, in early crystal sets. See Item A1318 The term Uralium is just as it says on the tin a trade name and the type of composition of the crystal is possibly Iron Pyrite or Galena. The same could be said of Hertzite. See Items A1494. The tin of Uralium also contains a spare wire coil known as a ''Cats Whisker''. Uralium is listed as a supposed new metallic element announced in 1879, its existence has not been confirmed.


Bruce Hammond Collection

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A1499

Image of VARIABLE RESISTANCE & POTENTIOMETER, 1940's

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VARIABLE RESISTANCE & POTENTIOMETER, 1940's

Two adjustable resistances with straight and circular adjustments. The straight version is made by Readirad and the circular is 400 ohms and is made by Igranic. Nothing is known about the maker Readirad.

Bruce Hammond Collection

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A1498

Image of AERIAL COUPLING/TUNING COILS ST400 , 1932

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AERIAL COUPLING/TUNING COILS ST400 , 1932

Aerial Coupling/Tuning coils used in ''Breadboard'' wireless sets during the 1930's. Marked inside ST 400 Aerial, which stands for Scott Taggard and was made for the home build ST400 set of 1932.

Bruce Hammond Collection

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A1497

Image of 'JIFFY' ALL WAVE CAPACITY AERIAL, 1940's

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'JIFFY' ALL WAVE CAPACITY AERIAL, 1940's

On back of the box reads:- Instructions for fixing. Remove Aerial and Earth wire from set. Connect the red core of the twin lead to Aerial socket on set and black core of twin lead to Earth socket of set, (if there is no earth lead disregard this lead). Connect long single lead to Earth. If you have already an Earth fixed you can join this to the existing Earth, otherwise it will be necessary to add an extra length of Earth wire to Earth tube in the ground or to a water pipe. The performance of ''Jiffy'' Aerial (Trade Mark) is dependent on an efficient earth. Main object of this Aerial is it's amazing convenience. Museum comment. Unless you live within sight of the Broadcast Transmitter or extremely close this device would not be of much use, what is inside is a mystery, on test the only reading found was a capacitance of 0.001uF between input and output.

Bruce Hammond Collection

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A1496

Image of VARIABLE CONDENSERS, 1940's

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VARIABLE CONDENSERS, 1940's

3 Variable condensers used in early wireless receivers, two in original boxes, the Graham Parish Litlos type is 0.0003uF. Price on the box 2/-, the Wavemaster is .00016uF.

Bruce Hammond Collection

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A1495

Image of CRYSTAL TO CRYSTAL DETECTOR, 1930's

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CRYSTAL TO CRYSTAL DETECTOR, 1930's

Detecting or Demodulating the wireless waves in the early days always seemed to be an enigma, eventually the thermionic diode proved a commercial solution, but much work was to be done with other devices, such as crystals such as Galena (Lead Sulphide) with a simple wire known as a ''Cats Whisker'' touching the surface, this was the forerunner to the Germanium Diode, which replaced many of these devices. See A1432 and A1435. Many attempts were made to create a junction between two different crystals as in this case, like the cat’s whisker method the junction is moveable, giving the impression that better reception can be found by touching the right spot. The type of crystal used in this case is unknown, Tellurium and Zincite (Perikon) is one such possibility, but many more were tried. Crystal receivers were to become popular alternatives to expensive valve sets in the 1920's and the ordinary working man would make his own set at home, creating a popular pastime.

Bruce Hammond Collection

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A1494

Image of GRID LEAK CAPACITOR/RESISTORS & LISSEN CHOKE, 1930's

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GRID LEAK CAPACITOR/RESISTORS & LISSEN CHOKE, 1930's

A Grid Leak resistor is normally used between the grid of a thermionic valve and ground, in order for the valve to function correctly, if the grid was connected to a low impedance source such as a tuning or coupling coil then a capacitor is added across this resistor to provide a low impedance path. Far Left. Lisson HF Choke 76mH not marked. Middle back. Lisson 0.0002uF Mica Condenser with resistor clips and box. Middle Front. Lisson dual holder with two resistors, the terminals are marked LT & G (grid) on one side and P (plate) & HT on the other. Right back. Dubilier Mica Condenser Type 620 0.0003uF and resistor on clips. Front right. Telsen Grid Leak resistor holder and box.
Bruce Hammond Collection

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A1493

Image of INTERVALVE TRANSFORMERS, 1930's

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INTERVALVE TRANSFORMERS, 1930's

Transformers designed for coupling valves between the anode of first valve to the grid of the next. These were used in early breadboard type radio's home made or manufactured. The item on the left was made by Radio Instruments of Croydon around the 1930's.

Bruce Hammond Collection

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A1492

Image of 2 LIGHT SWITCHES & 4 AMP PLUG SUPPRESSOR, 1940's

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2 LIGHT SWITCHES & 4 AMP PLUG SUPPRESSOR, 1940's

Back right, Porcelain toggle light switches, notice the wire entry from the side, the house wiring would have been on the surface. Front right, Turn type switch, most common in European countries this has two positions and can be used to switch two independent circuits. The Aerialite suppressor plug adaptor is rated at 4 amps and fits a standard round 3 pin 5 amp plug, this was used to suppress radio frequency interference from appliances such as Vacuum cleaners from wireless reception, with it's original box, made by Aerialite of Stalybridge Cheshire.

Bruce Hammond Collection

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A1491

Image of GENTS MASTER CLOCK TYPE C7, 1950's

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GENTS MASTER CLOCK TYPE C7, 1950's

Gledhill and Brook put their name on it, and Gents of Leicester supplied it, Parsons and Ball Manufacturing made it. Using the 'Pulsynetic' principle which swings and impulses the pendulum with a gravity arm every 30 seconds. The gravity arm is then raised and reset using a magnetic solenoid. It is different from the GPO clock Item A0073 which uses a simpler 'Hipp Toggle' principal.
Removed from The Whippendell Electric Works in Watford.


SEE http://west-penwith.org.uk/misc/gent.htm

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A0949

Image of GLEDHILL BROOK/GENTS SLAVE CLOCK, 1940's

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GLEDHILL BROOK/GENTS SLAVE CLOCK, 1940's

Gents of Leicester Slave clock supplied by Gledhill Brook for Master clock unit Item A0949, and donated by the Wemco factory in Whippendell Road Watford.

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A1327

Image of FACTORY BELL TIMER UNIT, 1950's

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FACTORY BELL TIMER UNIT, 1950's

Removed from The Whippendell Electric Works in Watford. Driven by a long case clock Item A0949, and used to ring bells for tea breaks, clocking on and off times Etc. In use during the second World War, and was installed long before that.
Commonly known as a "Bell Ringer".

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A0824

Image of NATIONAL TIME RECORDERS  FACTORY BELL TIMER AND CLOCK, 1950's

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NATIONAL TIME RECORDERS FACTORY BELL TIMER AND CLOCK, 1950's

It would appear that although Blick became the main user of National Time Recorders, NTR continued to supply recorders under their own name , an instruction book (not in the museum's possession) which gives Cray Avenue, St Mary Cray, Kent, as the Factory and head office address and shows that the company at that time had branch offices and local service departments in London, Birmingham, Bristol, Dublin, Glasgow, Leeds, Manchester, Newcastle and Sheffield. The booklet is unfortunately undated but the telephone number for the London office was 01-928 6641.

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A1291

Image of WORKS CLOCKING MACHINE & CARD RACK, 1950's

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WORKS CLOCKING MACHINE & CARD RACK, 1950's

This is an example of a time clock used for employees to log starting and finishing times. Inside one of the card slots was a punch card dated 10 Nov 1943, a lady whose name is creased out, was five to six minutes late every morning, 15 minutes would have been docked from her pay every day that she was late.
Removed from The Whippendell Electric Works in Watford. Driven by a long case clock Item A0949,

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A0783

Image of NIGHT-WATCHMAN TOUR CLOCK, 1950's

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NIGHT-WATCHMAN TOUR CLOCK, 1950's

Night Watchmen had to carry this clock to prove they had carried out their tour correctly and at the correct times.

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A1143

Image of NIGHT WATCHMAN'S  ELECTRIC LAMP, 1930's

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NIGHT WATCHMAN'S ELECTRIC LAMP, 1930's

Fitted with two Edison Type BS 1.5 volt batteries.

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A0213

Image of DIRECT CURRENT ELECTRICITY METER, 1930's

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DIRECT CURRENT ELECTRICITY METER, 1930's

The National Grid was introduced in 1926. Power Stations such as Battersea, built in 1933, were to supply a grid of constant power to the entire nation. However building the plants and installing the power lines took nearly ten years.

Some homes up to the Second World War were still using gas or limited electricity from local private companies, some supplying Direct Current of 110 volts. Early wireless's would be battery only, and DC was more convenient.

This equipment was driven by an escapement which was wound up by the supply electrically, this drove the dials, their movement was controlled by two pendulums moving over the coils carrying the supply current, the more current drawn the faster the pendulums would swing, in a circular movement above the coils, this in turn moved the dials . No current at all, no movement.

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A0193

Image of CAMBRIDGE SPOT GALVANOMETER, 1950's

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CAMBRIDGE SPOT GALVANOMETER, 1950's

Spot Galvanometer with a 450 ohm movement made by Cambridge Instruments. In working order.

Donated by L.G.Bray

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A1521

Image of MIRROR GALVANOMETER AND STAND, 1950's

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MIRROR GALVANOMETER AND STAND, 1950's

Calibrated scale for use with Mirror Galvanometers such as Items A0880. A0191 and A0202. The dot of light reflected by the mirror in instrument is displayed on scales like these.

Donated by Desmond Squires

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A1376

Image of WESTERN ELECTRIC GALVANOMETER

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WESTERN ELECTRIC GALVANOMETER

Made by the Western Electric Company in America during 1918. A moving coil meter called in this case a Galvanometer, with a full scale deflection of 20 Milliamp s, today it would be called just a moving coil meter. The movement is made by WECO (Western Electric Company) and the horseshoe magnet made by Weston Electric Company.

Nortel Collection

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A1355

Image of CAMBRIDGE UNIPIVOT GALVANOMETER, 1920's

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CAMBRIDGE UNIPIVOT GALVANOMETER, 1920's

Based on Jacques Arsène D'Arsonval's moving coil galvanometer, manufactured on a large scale by the Weston Electrical Instrument Company of Newark, New Jersey, Robert William Paul (1869-l943) devised an instrument in which the moving parts were supported on a single bearing giving lower friction and therefore greater sensitivity. Other unipivot instruments followed. His instruments gained international recognition, winning gold medals at the 1904 St Louis Exposition and the 1910 Brussels Exhibition. In November 1919, his business was bought by the Cambridge Scientific Instrument Company, which was renamed "The Cambridge and Paul Instrument Company." Cambridge Scientific Instrument Company was a company founded in 1881 by Horace Darwin (1851-1928) and Albert George Dew-Smith (1848-1903) to manufacture scientific instruments. Their partnership became a Limited Liability Company in 1895. In 1920 it took over the R.W. Paul Instrument Company of London, and became The Cambridge and Paul Instrument Company Ltd. The name was shortened to the Cambridge Instrument Company Ltd. in 1924 when it was converted to a Public limited company. The company was finally taken over by the George Kent Group in 1968, forming the largest independent British manufacturer of industrial instruments.

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A1333

Image of W G PYE CO LTD TANGENT GALVANOMETER, 1900's

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W G PYE CO LTD TANGENT GALVANOMETER, 1900's

A tangent galvanometer is an early measuring instrument used for the measurement of electric current. It works by using a compass needle to compare a magnetic field generated by the unknown current to the magnetic field of the Earth. It gets its name from its operating principle, the tangent law of magnetism, which states that the tangent of the angle a compass needle makes is proportional to the ratio of the strengths of the two perpendicular magnetic fields. It was first described by Claude Servais Mathias Pouillet in 1837.

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A0754

Image of PHILIP HARRIS TANGENT GALVANOMETER, 1900's

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PHILIP HARRIS TANGENT GALVANOMETER, 1900's

Used for measuring very small currents of electricity which when passed through the coil would deviate the needle from the magnetic north. See A0754.

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A0258

Image of GRIMSDELL DIX GALVANOMETER, 1900's

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GRIMSDELL DIX GALVANOMETER, 1900's

Astatic galvanometer made by Grimsdell Dix Acton London. An Astatic type has two needles in parallel mounted in opposite direction, to defeat the effect of the earth's field.

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A0192

Image of PHILIP HARRIS MIRROR GALVANOMETER, 1950's

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PHILIP HARRIS MIRROR GALVANOMETER, 1950's

The mirror galvanometer was later improved by William Thomson, later to become Lord Kelvin. He would patent the device in 1858.
Thomson reacted to the need for an instrument that could indicate with sensibility all the variations of the current in a long cable. This instrument was far more sensitive than any which preceded it, enabling the detection of the slightest defect in the core of a cable during its manufacture and submersion. Moreover, it proved the best apparatus for receiving messages through a long cable.
A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror. The mirror reflects a beam of light, which projects onto a meter, and acts as a long, weightless, massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models.

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A0202

Image of CAMPBELL VIBRATION TYPE No 106 MIRROR GALVANOMETER of 1912

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CAMPBELL VIBRATION TYPE No 106 MIRROR GALVANOMETER of 1912

Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. The most common uses were as recording equipment for seismometers and submarine cables used for telegraphy.
This model made by the Cambridge and Paul instrument Co has a mirror suspended from two threads instead of one. And is known as a Bi-filar type. Originally conceived by Albert Campbell. See the history above.
In December 1919 the Cambridge Scientific Instrument Company took over the smaller but successful Robert W. Paul(1869-1943) Instrument Company and became The Cambridge and Paul Instrument Company Ltd.

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A0191

Image of CAMBRIDGE INSTRUMENTS MIRROR GALVANOMETER, 1950's

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CAMBRIDGE INSTRUMENTS MIRROR GALVANOMETER, 1950's

Mirror Galvanometer standard design of the period. These instrument were becoming obsolete as Oscilloscopes were taking over,and have in this form have fallen out of use. Mirror galvanometer systems are now used as beam positioning elements in laser optical systems.

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A0880

Image of PHILIP HARRIS GALVANOMETER WITH SCALE, 1950's

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PHILIP HARRIS GALVANOMETER WITH SCALE, 1950's

A mirror is hung on a gold thread between an electromagnet , the mirror moves according to current in the coil. A light is reflected of the mirror onto a distant scale amplifying the reading. Used for measuring small electrical currents by amplifying the movement of an armature with a mirror attached to it suspended between a coil. A light is shone onto the the mirror and reflected onto a scale some distance away. This model has a needle and scale also

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A1547

Image of ADAM HILGER MIRROR GALVANOMETER WITH VIEWING SCREEN, 1950's

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ADAM HILGER MIRROR GALVANOMETER WITH VIEWING SCREEN, 1950's

A mirror galvanometer is a mechanical meter that senses electric current, except that instead of moving a needle, it moves a mirror. The mirror reflects a beam of light, which projects onto a meter, and acts as a long, weightless, massless pointer. In 1826, Johann Christian Poggendorff developed the mirror galvanometer for detecting electric currents. The apparatus is also known as a spot galvanometer after the spot of light produced in some models.

Donated by Ken Willis

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A0913

Image of PITH BALL ELECTROSCOPE, 1950's

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PITH BALL ELECTROSCOPE, 1950's

Pith ball for demonstrating Electrostatic energy, when the rod is rubbed with silk it generates a static charge which attracts the ball when placed in its proximity. Invented by British weaver's apprentice John Canton in 1754. This model was used by schools from the 1950's, and made by Philip Harris Ltd.

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A1528

Image of CROOKES TUBE WITH EVACUATION PORT, 1930's

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CROOKES TUBE WITH EVACUATION PORT, 1930's

For observing the Litho of discharge effects at different pressures. The invention of the diffusion pump by the German physicist Wolfgang Gaede in 1915, with important improvements by the American chemist Irving Langmuir, to which several different types of discharge tubes could be connected to remove the atmosphere.The most famous one is the Lenard tube, invented much earlier. (See The Cathode Ray tube site, Crookes tubes page 3)
The basic Crookes tube is a glass tube closed of at each end and an opening to evacuate the air. Two electrodes are sealed into the glass at each end, a voltage is placed across the tubes via the terminals and the air is gradually pumped out until a current is detect with amp meter. using this experiment scientist could learn the different characteristics of voltage flow in a vacuum. In 1855, Geissler invented the mercury vacuum pump thus making it possible to produce good quality vacuums in laboratory equipment.

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A1382

Image of ZAMBONI PILES, 1954

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ZAMBONI PILES, 1954

A Zamboni pile is an "electrostatic battery" and is constructed from discs of silver foil, zinc foil, and paper. Discs of approx. 20 mm diameter are assembled in stacks which may be several thousand discs thick and then either compressed in a glass tube. Zamboni piles have output potentials in the kilovolt range, but current output in the nanoampere range. The famous Oxford Electric Bell which has been ringing continuously since 1840 is thought to be powered by a pair of Zamboni piles.

Donated by Ken Willis

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A1359

Image of OERTLING SCIENTIFIC BALANCE, 1950's

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OERTLING SCIENTIFIC BALANCE, 1950's

By means of a prism and viewing screen, illuminated by a torch bulb, the miniature scale can be read accurately.
Air dampers in brass cylinders are used to stabilise the movement.

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A0125

Image of PHILIP HARRIS SCALES, 1950's

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PHILIP HARRIS SCALES, 1950's

Simple version of scales used in Laboratories and workshops.

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A0124

Image of OERTLING PRECISION BALANCE, 1970's

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OERTLING PRECISION BALANCE, 1970's

Model 142 Scientific Scales used by Chemists and Laboratories.

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A1043

Image of TESLA COIL, 1950's

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TESLA COIL, 1950's

The Tesla Coil was originally designed by Nicola Tesla in 1891 to produce very high voltages. His theories eventually lead to a possible means of transmitting power via a large aerial, replacing power lines, although the first aerial was made in America it never became a practicality. This is a model made for classrooms.

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A1022

Image of GRIFFIN AND GEORGE RUHMKORFF INDUCTION COIL, 1950's

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GRIFFIN AND GEORGE RUHMKORFF INDUCTION COIL, 1950's

In 1857, after examining a greatly improved version made by an American inventor, Edward Samuel Ritchie, Ruhmkorff improved his design (as did other engineers), using glass insulation and other innovations to allow the production of sparks more than 30 centimetres long.
Ruhmkorff patented the first version of his induction coil in 1851, and its success was such that in 1858 he was awarded a 50,000-franc prize by Napoleon III for the most important discovery in the application of electricity.
He died in Paris in 1877.

Bruce Hammond Collection

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A1156

Image of PHILIP HARRIS RUHMKORFF INDUCTION COIL, 1930's

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PHILIP HARRIS RUHMKORFF INDUCTION COIL, 1930's

Shown working, with the 6 inch spark.

Heinrich Daniel Ruhmkorff (January 15, 1803 in Hanover – December 20, 1877 in Paris) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil.)
Ruhmkorff was born in Hanover. After an apprenticeship with a German mechanic, he moved to England. Biographies say that he worked with the inventor Joseph Bramah, but this is unlikely since Bramah died in 1814. He may, though, have worked for the Bramah company.
In 1855, he set up a shop in Paris, where he gained a reputation for the high quality of his electrical apparatus.

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A0947

Image of EUREKA 6 INCH RUHMKORFF INDUCTION COIL, 1930's

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EUREKA 6 INCH RUHMKORFF INDUCTION COIL, 1930's

Electromagnetic induction was discovered by Michael Faraday (1791-1867).
In 1831 Nicolas Callan (1799-1864) invented the Induction coil.
In 1836 they were used for medical complaints such as skin disorders, and to power X ray machines.
Marconi used one for his experiments prior to developing his system at Poldhu in Cornwall for the first transatlantic transmission. Coils like this were used in spark transmitter systems for the next 30 years.
Later coils such as this unit, were made for schools and Colleges as demonstration units.

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A0135

Image of 5 INCH INDUCTION COIL, 1950's

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5 INCH INDUCTION COIL, 1950's

In several of Jules Verne's science-fiction novels, so-called "Ruhmkorff lamps" are mentioned. These were an early form of portable electric lamp. The lamp consisted of a Geissler tube that was powered by a battery-powered Ruhmkorff induction coil, an example of one (made much later)is shown here.

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A0966

Image of LECLANCHE CELL, 1896

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LECLANCHE CELL, 1896

The cell was invented by Georges Leclanche' in 1866, it is the forerunner of modern Zinc Carbon dry cells. In the centre is a porous cylinder filled with Manganese Dioxide and in the centre of this is a carbon rod. Outside of the cylinder is a zinc rod. The jar would normally be filled with Ammonium Chloride. The Positive terminal is the carbon rod and the zinc is negative. The voltage obtained is 1.5 Volts.

Georges Leclanché (1839 - 1882) was a French electrical engineer chiefly remembered for his invention of the Leclanché cell; one of the first modern electrical batteries and the forerunner of the modern dry cell battery.
The original form of the cell used a porous pot. This gave it a relatively high internal resistance and various modifications were made to reduce it. These included the "Agglomerate block cell" and the "Sack cell".

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A0186

Image of GRENET CELL, 1888

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GRENET CELL, 1888

The power source used by Thomas Edison for his perfected Phonograph of 1888. The Grenet cell was invented by the German Johan Christian Poggendorff (1796-1877). Called Grenet Cell because he made a practical version possible. Used as a source of power before the Dry Battery became available. It consists of three plates in a jar filled with 17 parts potassium dichromate dissolved in 100 parts of distilled water with the addition of 22 parts sulphuric acid. The two positive plates are made of retort graphite, the negative Zinc that can be raised or lowered into the solution; this prevents corrosion when not in use. These units come in varying sizes from 1/3 to 3 Litres.

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A0185

Image of SMALL ELECTROSCOPE IN LABORATORY FLASK, 1890's

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SMALL ELECTROSCOPE IN LABORATORY FLASK, 1890's

Used for the the detection of electrostatic charges. If a charged item such as a Ebonite rod that has been rubbed is held near the the brass terminal, the small foil leaf will deflect away from the mounting.

Bruce Hammond Collection

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A1149

Image of ELECTROSCOPE, 1900's

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ELECTROSCOPE, 1900's

The Electroscope was used for the the detection of electrostatic charges. If a charged item, (such as an Ebonite rod that has been rubbed) is held near the the brass terminal, the gold leaf will deflect away from the mounting.

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A0259

Image of PHILIP HARRIS ELECTROSCOPE, 1890's

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PHILIP HARRIS ELECTROSCOPE, 1890's

Used for the the detection of electrostatic charges. If a charged item such as a Ebonite rod that has been rubbed is held near the the brass terminal, the gold leaf will deflect away from the mounting.

Bruce Hammond Collection

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A1148

Image of TANDY 160 IN ONE, 1980's

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TANDY 160 IN ONE, 1980's

Hobby kit for children and adults to learn electronics. A popular pastime from the 1900's to the 1980's. A version of this equipment can still be found today, and is still used as a teaching aid.

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A0104

Image of R & J BECK MICROSCOPE, 1900's

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R & J BECK MICROSCOPE, 1900's

Microscope for medical and scientific use in laboratories and colleges. Complete with slides lens's and accessories. James Smith, a scientific instrument maker, commenced making microscopes in 1839 and took Richard Beck into partnership in 1847 trading as Smith & Beck at 6 Coleman Street, London. In 1851 Joseph Beck, the brother of Richard Beck, started working for the firm and became a partner in 1857 when the business name became Smith, Beck & Beck. When Smith retired in 1865 the business address was 31 Cornhill and the trading name changed to R & J Beck.

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A1365

Image of MICROSCOPE, 1900's

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MICROSCOPE, 1900's

Simple brass microscope, still in excellent working order, the wooden box is very basic.

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A0126

Image of 6  GRIFFIN AND TATLOCK  VACUUM TUBES IN A RACK, 1950's

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6 GRIFFIN AND TATLOCK VACUUM TUBES IN A RACK, 1950's

The Cross vacuum scale demonstrates the phenomenon of discharge at different pressures. The pressure in the tubes varies between 40 Torr (mm/Hg), the lowest vacuum in the left tube, to 0.03 Torr the highest vacuum in the right tube.

It is in this high vacuum, used in many Crookes tubes, that X-Ray's are produced.


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A0948

Image of HILGER SPECTROMETER, 1960's

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HILGER SPECTROMETER, 1960's

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state. This equipment uses the 'Spekker' Principal, a Registered Trade Mark.

Donated by L.G.Bray

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A1522

Image of ABSORBIOMETER, 1940's

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ABSORBIOMETER, 1940's

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state.

Donated by Ken Willis

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A0915

Image of PHOTO ELECTRIC ABSORBIOMETER, 1950's

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PHOTO ELECTRIC ABSORBIOMETER, 1950's

Using the 'Spekker' Principal and used for the analyses of Iron. A known sample is placed on one side of the lamp, and the specimen on the other. Filters are added, and the refraction of light is used to measure the unknown sample against the known one, using a Galvanometer. This Field of research is associated with Spectrometry

Donated by Ken Willis

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A0912

Image of MAGNET, 1960's

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MAGNET, 1960's

Could have been used in experiments on Magnetrons.

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A0946

Image of GEISSLER TUBES

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GEISSLER TUBES

One tube Marked 6132 for Helium. One Marked 6130 for Nitrogen. The others marked Oxegen Hydrogen and Carbon Dioxide. Heinrich Geissler (1814-1879) The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glass-blower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end, it would contain one or more of the following rarefied (thinned) gasses, such as neon, argon, or air, mercury or other conductive liquids, or ionizable minerals or metals, such as sodium. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines. The museum has several Geissler Tubes which can be demonstrated.

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A0969

Image of 5 X GEISSLER TUBES, 1950's

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5 X GEISSLER TUBES, 1950's

Illuminated

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A0969

Image of CROOKES TUBE, 1950's

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CROOKES TUBE, 1950's

Used in class rooms to demonstrate high voltage effects on evacuated tubes,or Cathode Rays. Sir William Crookes circa 1875. (1832-1919) The Railway tube or Paddle Wheel demonstrates Kinetic Energy.
The electrons bounced at the paddles (which are covered
with a small amount of a Mineral which will glow for effect), this will turn
the paddle wheel and move from one end of the tube to the other.
Crookes thought that Cathode Rays had momentum, but in 1903 J.J.Thomson proved that the rays hitting the paddle heated the gas on that side causing it to expand, as the gas on the other side remained cool, the vane moved away from the ray.
The railway tube was one of the models
Crookes demonstrated in his famous lecture in
Sheffield 1879.

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A0264

Image of CROOKES TUBE, 1950's

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CROOKES TUBE, 1950's

Illuminated

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A0264

Image of CROOKES TUBE 'MALTESE CROSS', 1930's

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CROOKES TUBE 'MALTESE CROSS', 1930's

Used to demonstrate cathode rays. A negative voltage is connected to the small end and a positive connected to the cross. The tube is evacuated of air, and when the voltage is applied, electrons (cathode rays) travel from the small electrode towards the cross, some hit the cross while others carry on and illuminate the end of the tube leaving a well defined shadow. This was the first cathode ray tube, probably attributed to Johann Wilhelm Hittorf in 1869, the same period as Crookes was experimenting.

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A0265

Image of MALTESE CROSS, 1950's

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MALTESE CROSS, 1950's

Illuminated

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A0265

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Used to demonstrate the effects of high voltage on liquids and gases in Schools and Universities. The yellow area is a liquid called Fluorescein, the Green Glass is Uranium Glass which is the element that glows, the elements are producing three colours in all, which glow yellow, green and violet, when hit by electrons created by a very high voltage,


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A0883

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Illuminated

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A0883

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Geissler tubes, were named after the man who first devised them (1814-1879), to demonstrate the effect of high voltages on different gases or air that has been rarefied. This one would have been made for a University or College. The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end. A Geissler tube contains one or more of the following rarefied (thinned) gasses, such as neon, argon, or air; mercury or other conductive liquids. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines.

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A0851

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Illuminated

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A0851

Image of SMALL CROOKES TUBE WITH CRYSTALS, 1890's

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SMALL CROOKES TUBE WITH CRYSTALS, 1890's

Used in class rooms to demonstrate high voltage effects on evacuated tubes and enclosed crystals. Sometimes referred to as a 'Cows Udder'.

Bruce Hammond Collection

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A1150

Image of SMALL CROOKES TUBE WITH CRYSTALS

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SMALL CROOKES TUBE WITH CRYSTALS

Illuminated

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A1150b

Image of CROOKES TUBE WITH BUTTERFLY, 1950's

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CROOKES TUBE WITH BUTTERFLY, 1950's

Used in class rooms to demonstrate high voltage effects on evacuated tubes and Chemicals. The butterfly is made of metal, coated in different minerals, when the electrons hit the elements they glow in the associated colour for that type. The principal is similar to a modern fluorescent tube. We can demonstrate this item in the museum along with a number of other electrical objects.

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A1135

Image of CROOKES TUBE WITH BUTTERFLY, 1900's

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CROOKES TUBE WITH BUTTERFLY, 1900's

Illuminated

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A1135

Image of WIMSHURST MACHINE, 1890's

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WIMSHURST MACHINE, 1890's

This electrostatic device was invented between 1880-1883 by British inventor James Wimshurst. It was used for generating high voltages, the machines were frequently used to power X Ray tubes.

The Wimshurst Machine belonged to a class of generators called influence machines, they separated electric charges through electrostatic induction or influence.

The Wimshurst Machine is self-starting, meaning it doesn’t need external electrical energy, it does however, need mechanical power and by turning the handle very quickly the two glass disks and their metal sectors rotate in opposite directions passing the crossed metal neutraliser bars and their brushes.

An imbalance of charges is induced, amplified and collected by two pairs of metal combs with points placed near the surfaces of each disk, this creates a spark, and the accumulated energy can be collected and stored in the two “Leyden Jars”

Bruce Hammond Collection

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A1153

Image of WIMSHURST GENERATOR, 1950's

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WIMSHURST GENERATOR, 1950's

Wimshurst built these machines between 1880 and 1883.

This unit was used in schools and colleges up to the early 1980's and is not antique although they are now seldom seen. It was used as a training aid in a subject that is no longer considered important in a world of computers.

The two disks rotate in opposite directions when the handle is turned. Strips of foil on the disks are rubbed with two wire brushes, static is picked up by prongs positioned close to the disks and stored in two jars (Leyden Jars). When the charge is sufficient a large spark discharges the stored energy across a gap by two brass rods.

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A0114

Image of GPO METER IN LEATHER CASE, 1960's

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GPO METER IN LEATHER CASE, 1960's

Test meter for GPO engineers with instructions for use. Very basic knob and terminals used with a variety of shunts. Marked on the front label (310506) 4 GPO TRA. 64/10. No more is known at present.

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A1568

Image of AVO Mk 2 VALVE CHARACTERISTIC METER, 1950's

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AVO Mk 2 VALVE CHARACTERISTIC METER, 1950's

Valve tester used by Maintenance engineers in the Radio and TV trade and others, for checking the working Characteristic's of a valve under operating conditions.

Donated by David Martin

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A1534

Image of DAWE INSTRUMENTS SOUND LEVEL METER, 1960's

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DAWE INSTRUMENTS SOUND LEVEL METER, 1960's

Sound level meter containing 7 sub miniature valves. Used for measuring sound intensity in the range 30 to 130 decibels. Powered by one High Tension and two low-tension batteries.

Donated by John Barnes

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A1487

Image of H. TINSLEY THERMOCOUPLE POTENTIOMETER Type 4606C, 1950's

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H. TINSLEY THERMOCOUPLE POTENTIOMETER Type 4606C, 1950's

A thermocouple consists of two junctions of dissimilar metals. If the two Junctions are at different temperatures a voltage is produced which, for small temperature differences and accuracy was measured using a potentiometer. To achieve absolute temperature measurement one of the junctions must be kept at a known temperature, often by melting ice.

The thermocouple potentiometer removes the inconvenience of having to use melting ice for each measurement by measuring the temperature of the reference junction. The measured temperature can then be corrected to the standard cold junction temperature of 0 degrees C.

Donated by John Barnes

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A1486

Image of PYE SCALAMP FLUXMETER, 1950's

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PYE SCALAMP FLUXMETER, 1950's

An internal lamp sends a beam to a mirror attached to the movement of the meter; the beam is then reflected onto the screen as a vertical line. This makes the instrument very sensitive. The use of this instrument is to measure magnetic field, and it is known as a "Fluxmeter". A coil is connected to the input terminals and this can be used to measure changes in field strength. This technique pre-dates measurement of magnetic field by nuclear magnetic resonance which is a technique used in archaeological searches.

Donated by John Barnes

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A1484

Image of CASTELCO CALIPRE BATTERY CHECKER, 1940's

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CASTELCO CALIPRE BATTERY CHECKER, 1940's

Device for testing batteries, just by lighting a bulb, a good indication of a useful battery because it will test it under load, a bright light would indicate good. Not suitable for chargeable types.

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A1457

Image of AIR MINISTRY OHM METER, 1932

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AIR MINISTRY OHM METER, 1932

Air Ministry meter for measuring Ohms from .01 to 0.1 with power connection on the back for a battery and four terminals giving different ranges. It is dated 1932

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A1362

Image of SIEMENS ELECTRODYNAMOMETER  of 1881

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SIEMENS ELECTRODYNAMOMETER of 1881

An early current meter was the electrodynamometer of 1881.
It was used until the 1920s when it was replaced by the direct reading meter patented by Edward Weston.
The basic principle was laid out in an 1848 paper by Wilhelm Weber (1804-1891)


Used in the early 20th century, the Siemens electrodynamometer, for example, is a form of an electrodynamic ammeter, it has a fixed coil which is surrounded by another coil having its axis at right angles to that of the fixed coil. This second coil is suspended by a number of silk fibres, and to the coil is also attached a spiral spring the other end of which is fastened to a torsion head. If the torsion head is twisted, the suspended coil experiences a torque and is displaced through and angle equal to that of the torsion head.



Bruce Hammond Collection

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A1205

Image of WESTON ELECTRIC METER, 1930's

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WESTON ELECTRIC METER, 1930's

In 1886 Edward Weston developed a practical precision, direct reading, portable instrument to accurately measure electrical current, a device which became the basis for the voltmeter, ammeter and watt meter. This model dates from the 1930's

Nortel Collection

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A1348

Image of UNIPIVOT METER, 1930's

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UNIPIVOT METER, 1930's

In 1903 Paul introduced a new design of galvanometer, the ‘Unipivot’ galvanometer. It was a robust, easy-to-use, pivoted moving-coil instrument, more sensitive than previous instruments of this type and superior to the widely used moving-magnet instruments. This Instrument dates from the 1930's

Nortel Collection

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A1347

Image of TINSLEY CHART RECORDER, 1950's

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TINSLEY CHART RECORDER, 1950's

Chart Recorder with Indian ink type pen, used for measuring current, and driven by a 220vac motor.

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A0158

Image of POST WAR POCKET DOSIMETER, 1950's

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POST WAR POCKET DOSIMETER, 1950's

A radiation dosimeter is a pen-like device that measures the cumulative dose of radiation received by the device. It is usually clipped to clothing to measure the actual exposure to radiation.
Magnifying lenses (a low-power microscope) and an illumination lens, helps to read the dose by aiming the illumination lens at a light source and looking into the device.

For personal use, this is the most useful device to measure radiation, because biological damage from radiation is cumulative.

Dosimeters must be periodically recharged. The dosimeter is usually read before it is charged, and the dose is logged, to chart exposure.
In many organizations, possession of the recharger is limited to health physicists to prevent falsification of exposures.

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A0515

Image of EPSYLON TRAINER RADIATION METER No1, 1950's

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EPSYLON TRAINER RADIATION METER No1, 1950's

The unit is not very sensitive,and the scale is not calibrated, the word trainer indicates its nature.
This is a companion model, the trainer is used to teach the use of the Radiac Model No2. Item A1300.
The range is low so it will detect the weak training sources used to simulate radioactive fallout.
See Radiac No2, A1300 for more information.

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A1299

Image of No 1 POST WAR CONTAMINATION DETECTION METER, 1954

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No 1 POST WAR CONTAMINATION DETECTION METER, 1954

Radioactivity detection unit, produced after the Second World War as a result of the Cold War period. These units were made on instruction from the government, and supplied to all Councils and Military establishments.
It was expected that in the event of a Nuclear attack, they would be ready to measure contamination levels.

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A0513

Image of CONTAMINATION LIQUID HEAD DETECTOR, 1950's

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CONTAMINATION LIQUID HEAD DETECTOR, 1950's

Spare detector head for the contamination meter Item A0513.
For reading liquids

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A0514

Image of RUSSIAN POCKET DOSIMETER AND CHARGER, 1950's

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RUSSIAN POCKET DOSIMETER AND CHARGER, 1950's

Four pocket Dosimeters and charger unit, inside a Bakelite Case.
Used for detection of radiation.
This item was made in Russia

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A0979

Image of EK COLE METER SURVEY RADIAC No 2 RADIATION METER, 1955

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EK COLE METER SURVEY RADIAC No 2 RADIATION METER, 1955

The scale is not calibrated, The range switch has 4 positions 0 - 3 r/hr / Scale Indicator White (shown)
0 - 30 r/hr / Scale Indicator Blue
0 - 300 r/hr / Scale Indicator Red
Set Zero / White Scale Indicator
The meter can be read while in the carry case and a side flap opens to allow access to the controls.
Measures Gamma - Detects Beta
Beta detection is accomplished by removing the base plate and a barrier plate inside. The unit was used by the Civil Defence Post War. Although referred to as Geiger counters, most CD devices were radiological survey meters capable of measuring only high levels of radiation that would be present after a nuclear event. Required 2X 1.5Volt 1X 9Volt and 1X 30Volt Batteries. The Radiac Survey Meter No 2 or RSM was a 1955 meter which counted the particles produced by radioactive decay. This meter suffered from a number of disadvantages: it required three different types of obsolete batteries, it also contained delicate valves that were liable to failure and it had to be operated from outside the protection of the post.
These were favoured as they had been tested on fallout in Australia after the Operation Buffalo nuclear tests, and remained in use until 1982 by commissioning a manufacturer to regularly produce special production runs of the obsolete batteries.

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A1300

Image of DOSIMETER GEIGER COUNTER DRMB1, 1970's

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DOSIMETER GEIGER COUNTER DRMB1, 1970's

Measures down to point 01 of a Roentgen. The calibration source mounted in the cover has been removed for health and safety reasons.

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A1294

Image of EKCO BETA/GAMMA DOSE RATE METER Type 95/0030, 1970

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EKCO BETA/GAMMA DOSE RATE METER Type 95/0030, 1970

Unit used for measuring the strength of radiation over time, not suitable for contamination measurements, this unit will measure the amount of radiation that will be absorbed by coming into contact with the material on test, over one hour. The strength of the object on test is read in Roentgen/Hours, this means that although coming into contact with the object will cause absorption of radiation immediately, its seriousness is only measured if the contact is sustained over a period of time.

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A1357

Image of RADIATION METER/ PORTABLE ELECTROMETER, 1950's

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RADIATION METER/ PORTABLE ELECTROMETER, 1950's

Used to test for radiation leakages on X- Ray equipment.

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A0117

Image of THEODOLITE DIRECTOR No5 MK1, 1916

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THEODOLITE DIRECTOR No5 MK1, 1916

Theodolite dated 1916 with broad arrow indicating it has been adopted for military use.

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A1134

Image of LARM-U FIRE DETECTOR, 1930's

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LARM-U FIRE DETECTOR, 1930's

Early Fire detector using a small plastic disk tensioned by a spring, temperatures above habitable conditions will soften the plastic forcing the steel disks together, creating a circuit which could ring a bell or bells.

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A0314

Image of CASSELLA AIR FLOW METER, 1960's

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CASSELLA AIR FLOW METER, 1960's

Meter used for measuring air flow Velocity 200-3000 No L 11434

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A1020

Image of EARLY THERMOSTAT, 1930's

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EARLY THERMOSTAT, 1930's

Thermostat for a variety of uses.
May have been made for a specific piece of equipment.

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A0308

Image of EARLY THERMOSTAT, 1930's

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EARLY THERMOSTAT, 1930's

Early type thermostat using a sealed atmospheric chamber and a very strong spring.
A lever tilts a Mercury switch

Donated by Richard Currie

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A1013

Image of KELVIN AND WHEATSTONE BRIDGE, 1948

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KELVIN AND WHEATSTONE BRIDGE, 1948

Used for measuring an unknown resistance.
The Kelvin portion enables reading accurately very low resistance (below 1 Ohm). The Kelvin Bridge makes allowances for the high currents used for measuring very low resistances, as heat generated can cause errors.

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A1128

Image of HYDROMETER FOR WHISKY BY SIKES, 1960's

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HYDROMETER FOR WHISKY BY SIKES, 1960's

Used for measuring the specific gravity of Whisky.

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A0260

Image of EARLY MOVING COIL METER, 1900's

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EARLY MOVING COIL METER, 1900's

Early moving coil meter in wooden box with wall fixing or stand alone on two adjustable feet.

Bruce Hammond Collection

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A1210

Image of ROUND AMP METER, 1940's

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ROUND AMP METER, 1940's

General industrial meter for measuring power sources, with 270 degree scale.

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A0128

Image of GEC ROUND VOLT METER, 1940's

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GEC ROUND VOLT METER, 1940's

General industrial moving Iron meter for monitoring power sources.

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A0127

Image of VOLT AND AMP METERS, 1930's

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VOLT AND AMP METERS, 1930's

School Laboratory measuring meters, used in demonstration theatres, and before students were trained to use multi meters, when they started to come into use.
Volt meter is 0 to 10 volts
Amp meter is .5 To 3 amps.

Bruce Hammond Collection

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A1191

Image of WATSON KILOVOLT METER, 1940's

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WATSON KILOVOLT METER, 1940's

0 To 250 kilovolt meter, for Laboratory and College use, designed to be laid flat, as the terminals are underneath.
And WATSON 0 to 20 Milliamp meter,

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A0111

Image of WESTON ELECTRIC METERS, 1918

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WESTON ELECTRIC METERS, 1918

The calibration certificate for the ammeter is for Serial No 30940 ?
The meter shown is Serial No 23602.
The Voltmeter is dated 13 Jan 1920.

British-born American Chemist who revolutionized the Electro-plating industry, founded the Weston Electrical Instrument Company. A prolific inventor who held 334 patents, Edward Weston May 9, 1850 – August 20, 1936 helped revolutionize the measurement of electricity.

Weston's son, Edward Faraday Weston also received several patents regarding exposure meters.

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A0975

Image of NEWTON AND WRIGHT BRASS AMPMETER, 1930's

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NEWTON AND WRIGHT BRASS AMPMETER, 1930's

Surface mounting ampmeter for 0-25 amps in brass case.

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A0256

Image of CIRSCALE AMPMETER, 1930's

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CIRSCALE AMPMETER, 1930's

Meter calibrated for measuring direct current up to 300 amps. Requires an external shunt.

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A0255

Image of WR MORRIS HOT WIRE AMMETER, 1930's

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WR MORRIS HOT WIRE AMMETER, 1930's

Hot Wire Ammeters work the expansion and contraction of a piece of wire when heated by an electric current. Although not very accurate and prone to ageing effects of the wire, they were an inexpensive way of indicating currents of over 100 Milliamps.
Smaller current versions would have made the wire too fragile.

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A0722

Image of 'LAMPE METER' POWER METER ADAPTOR, 1930's

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'LAMPE METER' POWER METER ADAPTOR, 1930's

Power moving Iron meter for measuring domestic equipment, volts and amps are measured by inserting this device between the power lead.

Bruce Hammond Collection

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A1190

Image of DOMESTIC POWER METER BY SIEMENS LTD, 1930's

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DOMESTIC POWER METER BY SIEMENS LTD, 1930's

Plugged into a lamp socket, the appliance was plugged into the meter ,it then measured the current being drawn.
Used in the days when household power points were rare if not non existent, and electric irons were plugged into the light fitting.
The movement is of the moving Iron type.

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A0282

Image of PIFCO 'ALL IN ONE' AC & DC RADIOMETER, 1940's

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PIFCO 'ALL IN ONE' AC & DC RADIOMETER, 1940's

The Pifco 'All in One' Radiometer Measures in three ranges up 30 Milliamps, 6Volts or 240 Volts AC or DC from the same terminals on top of the unit. continuity is also possible for low resistance items such as transformers and valve heaters using the 5 pin valve base on the top of the unit, the reading is not callibrated in ohms. A 1.5 Volt battery fits inside the unit. Price for 7 or 9 pin valve adaptor 3/9d. Price for insulated test leads 3/6d pair.

Bruce Hammond Collection

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A1504

Image of PIFCO ALL IN ONE METER, 1920's

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PIFCO ALL IN ONE METER, 1920's

Meter for home workshops, with 5 ranges and 7 terminals, including a top centre terminal.
Advertised in The Wireless World 1932 for 12 Shillings and Sixpence

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A0309

Image of POCKET FOB METER FORIEGN MADE, 1940's

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POCKET FOB METER FORIEGN MADE, 1940's

Bakelite fob meter supplied by Curry's. Directions on the box reads:- Place plug on flex in negetive tapping, 8 Volt plug for L.T. & G.B. 120 Volt plug for H.T.

Bruce Hammond Collection

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A1505

Image of PARA VOLT FOB METER, 1920's

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PARA VOLT FOB METER, 1920's

Engineers pocket voltmeter. And the original box.
120 Volts Dc could have been the local mains voltage before 1930.

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A0301

Image of POCKET FOB WATCH  METER, 1920's

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POCKET FOB WATCH METER, 1920's

Engineers pocket meter, moving Iron type, which looks like a pocket fob watch.
120 Volts Ac or Dc could have been the normal mains voltage before 1930.

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A0300

Image of FOB VOLTMETER, 1930's

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FOB VOLTMETER, 1930's

Pocket meter for engineers.
120 Volts DC could be a normal mains voltage before 1930.

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A0299

Image of NADIR MULTI METER, 1930's

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NADIR MULTI METER, 1930's

Forerunner to the modern Multi Meter

Donated by Ken Willis

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A1093

Image of CAMBRIDGE PORTABLE pH METER, 1940

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CAMBRIDGE PORTABLE pH METER, 1940

A pH meter is an electronic instrument used to measure the pH (acidity or alkalinity) of a liquid
Donated by Ken Willis

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A1092

Image of HEILAN MOISTURE METER, 1930's

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HEILAN MOISTURE METER, 1930's

Early equipment for the measurement of moisture

Donated by Ken Willis

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A1094

Image of SHEATH CURRENT TESTER, 1930's

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SHEATH CURRENT TESTER, 1930's

Used by the GPO for measuring underground cable sheath current to detect breaks

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A1096

Image of SUBSTITUTION BOX, 1950's

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SUBSTITUTION BOX, 1950's

Substitution boxes are used for temporarily replacing resistors or capacitors that may be assumed faulty, by inserting a known value of a component into a circuit and conveniently adjusting the value if necessary.

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A0107

Image of ADVANCE SIGNAL GENERATOR TYPE E MODEL 2, 1949

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ADVANCE SIGNAL GENERATOR TYPE E MODEL 2, 1949

Well Known Signal Generator used by the Trustees, and in Radio and Telivision workshops for aligning Radio's and early Televisions during the 1950/60's. Covers 100Kc/s to 100Mc/s in six ranges , Band A : 100 - 300Kc/s
Band B : 300 - 1000Kc/s
Band C : 1 - 3 Mc/s
Band D : 3 - 10 Mc/s
Band E : 10 - 30 Mc/s
Band F : 30 - 100 Mc/s The manufacturers claim it had an accuracy of +/- of 1% over the whole range

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A1342

Image of TEKTRONIX OSCILLOSCOPE, 1960's

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TEKTRONIX OSCILLOSCOPE, 1960's

Large valve type Oscilloscope used in service Laboratory's throughout the world Usually mounted on a steel trolley

Donated by Mrs Banham

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A1016

Image of MARCONI TF868 LCR BRIDGE, 1950's

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MARCONI TF868 LCR BRIDGE, 1950's

A bridge for the measurement of, L= Inductors C= Capacitors & R= Resistances. A Bridge is a circuit of 3 Known values connected in a square configuration with the last portion the fourth for the unknown component, when the current across the bridge is at null or balanced the value of the unknown component is the same as its opposite counterpart.
Ranges:
L - 1µH to 100 Henrys
C - 1 pF to 100 µF
R - 0.1 Ohms to 100 Megohms
The test terminals are located on top of the instrument; the flat top provides a useful insulated platform for supporting the component to be tested. This also has printed basic instructions for use.

Donated by Frank Ibrahim

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A1489

Image of UNIVERSAL AVO MULTIMETER., 1930's

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UNIVERSAL AVO MULTIMETER., 1930's

The Universal AVO meter of 1933 Dated 1938. This was the first in the range of these famous instruments, and was replace by the model 40.

Avo Multimeters were the mainstay of the service industry in the 1950's to the 1990's and are still available today, but extremely expensive. The 'Automatic Coil Winder and Electrical Equipment Co.', Douglas Street, London SW1, later renamed to 'AVO Ltd.' (which should not be mixed up with 'Avo International Ltd.)
AVO is well known for it's very solid and reliable measuring instruments, and - coil winding machines.

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A0108

Image of AVO 25Kv DC Multiplier, 1950's

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AVO 25Kv DC Multiplier, 1950's

Adaptor for the AVO Model 8 and HR (high resistance) models, for measuring voltages up to 25 Kilo Volts.

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A1477

Image of AVO 10Kv DC MULTIPLIER , 1950's

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AVO 10Kv DC MULTIPLIER , 1950's

Adaptor for the AVO Model 8 and HR (high resistance) models, for measuring voltages up to 10 Kilo Volts.

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A1476

Image of AVO MINOR MULTI METER, 1930's

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AVO MINOR MULTI METER, 1930's

Cheapest of all AVO meters in original case, to change the range you simply re plug the leads.

In 1938 the AVO minor cost 45 Shillings.

Donated by Roger Smith

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A1009

Image of AVO MULTI MINOR MULTI METER, 1930's

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AVO MULTI MINOR MULTI METER, 1930's

AVO is well known for it's very solid and reliable measuring instruments.this unit was less expensive than the larger models, but unlike the Minor had a switch to change the range.

AVO 'Automatic Coil Winder and Electrical Equipment Co'.

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A0109

Image of AVO MODEL 7 MULTIMETER, 1950

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AVO MODEL 7 MULTIMETER, 1950

The model 7 was intended more for electricians and power engineers. The model 8 was better for bench electronic engineers. These meters were the classic instrument for test engineers in the radio and TV service industry for many years.

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A1331

Image of AVO MODEL 40 MULTIMETER, 1941

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AVO MODEL 40 MULTIMETER, 1941

This classic Avometer dated April 1941. At 333 Ohms-per-volt not designed for electronic equipment. It was advertised as a 'Power Engineer's' meter. Introduced in 1939 and initially supplied to the Admiralty.

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A1470

Image of AVO MODEL 40 MULTIMETER, 1964

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AVO MODEL 40 MULTIMETER, 1964

This classic Avometer was introduced in 1939. At 333 Ohms-per-volt not designed for electronic equipment. It was advertised as a 'Power Engineer's' meter. Introduced in 1939 and initially supplied to the Admiralty.

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A1332

Image of AVO MODEL 8 Mk4, 1970

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AVO MODEL 8 Mk4, 1970

In 1970 the Avometer model 8 Mk4 cost £34.80 and the case £5.50. Today the Avometer model 8 Mk7 is £500 plus The AVO Model 8 multimeter reached retirement after 58 years
(24/11/2008)
Possibly the most popular professional multimeter of the 20th Century, the venerable AVO Model 8 has reached retirement: the final Model 8 have left Megger’s Dover factory, where it has been produced since its introduction in 1951. Last off the line the Mk7.

Nortell Collection

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A1384

Image of AVODAPTER VALVE TESTER ADAPTERS, 1932

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AVODAPTER VALVE TESTER ADAPTERS, 1932

The units are plugged into a receiver between the valve under test, the set is switched on and after a warm up period with the leads connected to a test meter the performance of the valve can be measured.
The four and five pin unit in 1923 cost 25 Shillings and the seven pin unit cost twelve shillings and six pence.

Bruce Hammond Collection

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A1263

Image of AVO 160 VALVE TESTER, 1960's

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AVO 160 VALVE TESTER, 1960's

Useful for testing Military valves as well as commercial types. Basically the 'Automatic Coil Winder and Electrical Equipment Co.', Douglas Street, London SW1.
Later renamed to 'AVO Ltd.' (which should not be mixed up with 'Avo International Ltd.)
AVO is well known for it's very solid and reliable measuring instruments, and coil winding machines.

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A0103

Image of LAFAYETTE MULTIMETER, 1960's

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LAFAYETTE MULTIMETER, 1960's

Amateur large scale multi meter, from the 1960's. Uses obsolete battery for high resistance measurement.

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A0956

Image of SONIC BOOM DETECTOR, 1950's

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SONIC BOOM DETECTOR, 1950's

Developed as a prototype to measure sound pressure levels to evaluate damage caused by Military Jets flying over buildings.
New Laws regarding Supersonic aircraft flying over built up areas rendered it obsolete.
Similar units are now used to measure explosions.

Donated by Richard Currie

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A1015

Image of GPO ENGINEERS TOOL BAG, 1930's

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GPO ENGINEERS TOOL BAG, 1930's

Standard Issue GPO engineers tool bag of the period.

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A0518

Image of SHORTS GAS INDICATOR, 1900's

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SHORTS GAS INDICATOR, 1900's

Used for measuring the coal gas content in air by atmospheric pressure, and indicated by the percentage of coal gas.
The mechanics of the instrument are identical to that of a normal Barometer.

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A0323

Image of MANGANIN WIRE RESISTANCE UNIT, 1930's

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MANGANIN WIRE RESISTANCE UNIT, 1930's

Manganin was used in the 1930's as a replacement for Nickel Silver used up until then.
Manganin and Ureka wire was superceded by Nickel Copper and Nickel Chrome Alloys.

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A0334

Image of CAMBRIDGE POTENTIOMETER VOLTAGE BRIDGE, 1959

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CAMBRIDGE POTENTIOMETER VOLTAGE BRIDGE, 1959

Modern Scientific Bridge, with an in built accurate reference for the measurement of voltage

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A0201

Image of THERMASTER LOW TEMPERATURE INDICATOR, 1950's

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THERMASTER LOW TEMPERATURE INDICATOR, 1950's

Unit for measuring temperature from zero to 100 degrees centigrade.
The knob is turned until the needle centres between increase and decrease.
The temperature is read from the scale attached to the knob.

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A0212

Image of GRIFFIN & GEORGE STANDARD CELL, 1950's

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GRIFFIN & GEORGE STANDARD CELL, 1950's

The Weston cell, invented by Edward Weston in 1893, is a wet-chemical cell that produces a highly stable voltage suitable as a laboratory standard for calibration of voltmeters. It was adopted as the International Standard for EMF between 1911 and 1990. This cell produces 1.01859 Volts. It is a voltaic cell producing a constant and accurately known electromotive force that can be used to calibrate voltage-measuring instruments

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A1406

Image of WESTON NORMALCELL, 1950's

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WESTON NORMALCELL, 1950's

Standard voltage Cell for use with accurate measuring equipment such as the Wheatstone Bridge.

Edward Weston (May 9, 1850 – August 20, 1936) was an English chemist noted for his achievements in electroplating and his development of the electrochemical cell, named the Weston cell, for the voltage standard. Edward Weston was a competitor of Thomas Edison in the early days of electricity generation and distribution.
Weston' son Edward Faraday Weston also received several patents regarding exposure meters.

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A0333

Image of GPO EXCHANGE TEST SET 5422, 1960's

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GPO EXCHANGE TEST SET 5422, 1960's

Used in exchanges for testing equipment.
Marked DGM ATW 54220 Issue 4

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A0044

Image of GPO TEST SET No 36, 1950's

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GPO TEST SET No 36, 1950's

Test equipment used for detecting fractures in under ground lead sheathed cables.

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A0030

Image of GPO 37 MIRROR GALVANOMETER, 1954

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GPO 37 MIRROR GALVANOMETER, 1954

Galvanometer unit for use with other test gear.
May have originally come from Dollis Hill Laboratories.
And may have been made by H.W.Sullivan Ltd in 1954.

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A0076

Image of PO NON REACTIVE SLIDE WIRE AND BOX, 1920's

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PO NON REACTIVE SLIDE WIRE AND BOX, 1920's

This piece of equipment is in excellent condition and may have come from Dollis Hill Laboratories.

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A0077

Image of GPO 74101D OSCILLATOR, 1950's

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GPO 74101D OSCILLATOR, 1950's

This too may have come from the Dollis Hill Laboratories.

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A0075

Image of GPO 74101 TRANSMISSION TEST SET, 1950's

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GPO 74101 TRANSMISSION TEST SET, 1950's

Originally may have come from Dollis Hill Laboratories.

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A0074

Image of LEEDS AND NORTHRUP SPEEDOMAX 'H' CHART RECORDER, 1960's

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LEEDS AND NORTHRUP SPEEDOMAX 'H' CHART RECORDER, 1960's

Valve chart recorder, for measuring and recording on paper information collected by sensors sensitive to voltage or current readings, meaning it could record almost any equipment with a sensor attached to it.

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A0957

Image of CAMBRIDGE RESISTANCE BRIDGE CALENDAR & GRIFFITHS, 1887

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CAMBRIDGE RESISTANCE BRIDGE CALENDAR & GRIFFITHS, 1887

Resistance Bridge (Collins Patent) with pots normally containing a liquid, using pegs, which when dipped, creates a switch.
Messrs Calendar and Griffith invented their Bridge in 1878, it went on to be used well into the 1930's.

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A0976

Image of PO RESISTANCE BANK 375, 1940's

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PO RESISTANCE BANK 375, 1940's

Used by G.P.O. engineers as a reference for resistance measurement.
Type 375

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A0942

Image of GLUCK BAROGRAPH, 1960's

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GLUCK BAROGRAPH, 1960's

Modern example of air pressure measuring instrument in original style case.

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A0161

Image of MUIRHEAD D-972-A POTENTIOMETER , 1960's

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MUIRHEAD D-972-A POTENTIOMETER , 1960's

Direct Current measuring device used for accurate measurement of voltages. all voltage measurements are referenced from a 'Standard Cell' similar to Item A0333.

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A0882

Image of CABLE TENSION METER, 1960's

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CABLE TENSION METER, 1960's

Used by aerial cable engineers, such as the Post Office for telephone and telegraph lines, for tensioning the cable correctly.

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A0276

Image of ENGINEERS CLINOMETER, 1940's

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ENGINEERS CLINOMETER, 1940's

Used by engineers for checking gradients on structures.

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A0275

Image of RADAR KILOVOLTER HIGH VOLTAGE METER, 1950's

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RADAR KILOVOLTER HIGH VOLTAGE METER, 1950's

For measuring high voltages, probably a TV tubes high tension, the probe on the left is held on the voltage output to be tested, after the lead is connected to ground.
By adjusting the knob on the right the distance between the two balls is reduced untill the voltage sparks accross the gap, the voltage is then read from the scale.

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A0274

Image of WAR DEPARTMENT WHEATSTONE BRIDGE, 1940's

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WAR DEPARTMENT WHEATSTONE BRIDGE, 1940's

War Department Wheatstone Bridge for the accurate measurement of resistance.
Similar to the Post Office standard Wheatstone Bridge.

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A0330

Image of WAR DEPARTMENT RESISTANCE BRIDGE, 1915

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WAR DEPARTMENT RESISTANCE BRIDGE, 1915

Together with a Galvanometer and a standard voltage cell Like Item A0333, clipped into the pillars on the right of the instrument, accurate readings of long lines could be measured.
Can be been wired in a bridge configuration.

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A0332

Image of TELEGRAPH BRIDGE AND INSULATION TESTER, 1940's

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TELEGRAPH BRIDGE AND INSULATION TESTER, 1940's

Bridge and insulation tester used in telephone and telegraphy workshops.
Complete with Tangent Galvanometer.

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A0331

Image of LOGOHM MK 6 RESISTANCE BRIDGE, 1940's

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LOGOHM MK 6 RESISTANCE BRIDGE, 1940's

A battery operated resistance meter operated in a bridge configuration i,e, with three known resistance it is possible to identify the missing section of the circuit when all components are connected in a circle or bridge configuration. Sets like this were made by many manufacturers in the UK before mass production from Japan and China took over.

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A0744

Image of DC4 VALVE AMPLIFIER, 1950's

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DC4 VALVE AMPLIFIER, 1950's

Laboratory Volt meter with valve amplification providing a very high input resistance.

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A0740

Image of GPO EVERSHED AND VIGNOLES MEGGER, 1923

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GPO EVERSHED AND VIGNOLES MEGGER, 1923

Megger instrument for measuring very high resistances (leakages), using high voltages created by winding the handle on the end.
Used by the GPO on Telephone lines.

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A0582

Image of SURVEYORS  TROUGH COMPASS IN BOX, 1970's

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SURVEYORS TROUGH COMPASS IN BOX, 1970's

Surveyors compass's, which have a needle with small sideways movements and few degree marks. Designed to be small and portable, would be used with maps on site.

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A0715a A0715b

Image of MAGNETOMETER, 1900's

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MAGNETOMETER, 1900's

Also called a Gaussmeter, after Carl Friedrich Gauss in 1833. It measures the direction and strength of magnetic fields in the vicinity of other affecting objects.

The earth's magnetic field (the Magnetosphere) varies due to influences of rocks and ores in the ground or the interaction between particles from the sun affecting the Magnetosphere. This is an early instrument for measuring these effects. It could be mounted on a long rod and slid along taking readings at precise intervals.

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A0257

Image of SHARMAN PIPE OR CABLE FAULT LOCATOR, 1914

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SHARMAN PIPE OR CABLE FAULT LOCATOR, 1914

Patents 16799 15th July 1914 and 24056 15th Dec 1914 accredited this item to Alexander William Sharman, holder of 40 other electrical and scientific patents.

A transformer like search probe for locating breaks in metal pipes and cables which would be connected to the oscillator output (red lead) while the negative lead is connected to a metal stake which is driven into the ground to provide a return circuit. Headphones can be connected to the search probe or to the accessory search coil.

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A0204


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