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Museum Artifacts

The objects in this museum are not housed in one building. They can be viewed at various venues throughout South Africa. Some are on loan to, or owned by, cultural bodies and special interest groups. The intent is to preserve these objects for educational purposes, and to be viewed by the widest possible public. 

We attach to each object shown here, all that is known of that object. For those requiring a closer inspection of any item shown, a visit to the indicated current location may be necessary.​​

The IONOSPHERIC RECOR​DER circa 1948​​
Before submarine cables and satellites for transmitting telephone signals became available in the mid 1970s voice communication with overseas countries depended on short-wave radio. This form of transmission exploited the reflection of radio waves by the Ionosphere located hundreds of kilometres above the surface of the earth. The behaviour of this phenomenon was poorly understood and after WWII an international effort was launched to learn more about the technique.

TECHNICAL INFORMATION

It became essential to understand the variations in height of the Ionosphere and the range of frequencies reflected by these layers. Trevor Wadley, employed by the South African Council for Scientific and Industrial Research's (CSIR) Telecommunications Research Laboratory, was given the task of developing a suitable instrument for determining these parameters. The height was measured using Radar in the frequency range from 100 kHz to 20 MHz. Wadley devised unique equipment which generated bursts of radio signals over the full frequency range without band switching. Likewise his receiver tuned over the full band in a single smooth sweep. This achievement was unique and proved to be very successful. The results were recorded one frame at time on a 16 mm cinè camera and were shared internationally. Other countries developed similar equipment but the​ range of frequencies was covered in several steps and could not achieve the same elegant results.

Approximate dimensions 1m x 1m x 1m

The Ionospheric Recorder is part of the South African Institute of Electrical Engineers historical collection.

Tel: +2711 487 3003
Comments or enquiries: mppc@mweb.co.za or verdene@iafrica.com​

Following the success of his Ionosphere Recorder, Trevor Wadley realised that the technique could be extended to produce a radio receiver with continuous frequency coverage. In the early 1950s he produced the prototypes shown in the illustration.

TECHNICAL INFORMATION

Based on a stable 1 MHz crystal controlled oscillator the receiver covered all frequencies from 0 to 30 MHz without gaps. There were two frequency-selecting dials, the first chose the desired megahertz range and the second interpolated between successive megahertz steps. By clever design Wadley was able to achieve exceptional frequency stability combined with accurate tuning calibration. It was possible to set the desired frequency on a cold receiver and when the power was switched on the selected frequency would be available to within 5 kHz - such performance had never been achieved previously.

The Royal Navy chose to standardise on this receiver and a small (at that time) British electronics company, Racal, took on the manufacture. It was used all over the world and remained supreme until digital equipment took its place. A transistorised version was manufactured in South Africa, known as the Barlow-Wadley XCR-30, which was very popular with amateur radio enthusiasts all over the world. The Yaesu FRG-7 was produced under licence in Japan.

Approximate dimensions 400mm x 350mm x 250mm

The Wadley Receiver is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.

http://www.saiee.org.za

Tel: +2711 487 3003
Comments or enquiries: mppc@mweb.co.za or verdene@iafrica.com​

WIRE RECORDER circa 1948

Manufactured by Webster, Chicago.

http://www.videointerchange.com/wire_recorder1.htm

Before the development of oxide based magnetic tape, "glorified" steel piano wire was the dominant media of choice.

The technology of magnetic recording dates back to 1878, when Oberlin Smith proposed the idea of recording telephone signals onto a length of steel piano wire. Over the next thirty years the technology evolved at a "snail's pace"; stalled by lack of adequate and cost effective electronic amplification. By 1930, advances in electronics allowed the first commercially successful wire recorders to be introduced as dictating machines and telephone recorders in Europe and North America. During WWII, the machines found their way into the BBC who employed banks of them for sending messages to the French underground. Germany broadcast pre-recorded speeches by Adolf Hitler in quick succession from widely separated transmitters to confuse the allies. The early machines used large reels of steel tape at a speed of 1metre/second. The US Army & Navy also employed them for similar purposes in their operations centers. Following the war from 1947 to 1952, wire recorders became popular in America and across Europe, and started showing up in many homes.

The advent of oxide based magnetic tape had many benefits over steel wire.... Mainly the ability to record and playback in stereo. Thus magnetic tape put an end to the wire recording era.

Signals recorded on steel wire recorders have held up quite well over the years and the sound quality was fairly good considering the limited technology of the day.

Approximate dimensions: 430mm long x 290mm wide x 180mm deep.

A Wire Recorder is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.

http://www.saiee.org.za

Tel: +2711 487 3003
Comments or enquiries: mppc@mweb.co.za or verdene@iafrica.com​

The two coils mounted at the extremities of the pivoted beam were connected in series with four co-axial fixed coils placed above and below the moving coils. The magnetic fields produced by the current ​interact so as to unbalance the beam and weights are provided to restore the beams to the neutral position. Both AC and DC measurements were possible. International current standards were maintained by similar instruments.

Before World War Two and the formation of the South African Bureau of Standards, the University of the Witwatersrand provided a standardisation service for electrical measurements. This particular instrument was one of the measuring standards.

Approximate dimensions: 1 000mm x 120mm x 350mm

The Kelvin Current Balance is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.

http://www.saiee.org.za

Tel: +2711 487 3003
Comments or enquiries: mppc@mweb.co.za or verdene@iafrica.com​

BURNDEPT ETHOPHONE JUNIOR CRYSTAL SET circa 1925
(450kHz - 1200kHz 1925 price about £5)

Most listeners were using crystal sets to receive broadcasts in the early 1920s as they could not afford valve receivers. The Galena crystal and "Cats Whisker" diode detector required frequent readjustment. This, combined with the discomfort of wearing headphones, made listening to broadcasts a dedicated pastime. John Samuel Streeter's weekly broadcasts of selected gramophone recordings were transmitted from his Cape Town home from 1919 until September 1924.

Approximate dimensions: 150mm x 150mm x 250mm

The Burndept Ethophone Junior Crystal Set is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.

http://www.saiee.org.za

Tel: +2711 487 3003
Comments or enquiries: mppc@mweb.co.za or verdene@iafrica.com​

MARCONIPHONE circa 1925

A 2-valve-reaction detector and audio amplifier capable of driving an external loudspeaker at distances up to 60km from the transmitter. It required is a 4V accumulator, a grid bias battery and an HT battery. Long, short and medium waves were selected by means of the plug-in coil which was tuned by the rotating short circuited loop.

The Marconiphone is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa. It was donated to the SAIEE by the late G D Walker.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​

JOHAN​NESBURG OBSERVATORY LIGHTNING RECORDER
Manufactured in Budapest 1905

This remarkable lightning recorder is the only surviving instrument from the Transvaal Meteorological Station at the Johannesburg Observatory.

Its operation was based on the Marconi coherer wireless telegraphy receiver. The coherer is mounted between the two perforated brass posts to the left of centre of the instrument. Lightning impulses induced in an external antenna caused the coherer to conduct and operate the telegraph relay situated on the right hand side of the instrument. The relay activated the armature of the central assembly having a striker that de-cohered the coherer. The vertical arm attached to the armature held a pen which wrote on the helical chart rotated by the clock on the extreme left and a gong warned the operators that an event had been recorded.

Dimensions: 630 mm wide x 350 mm deep x 285 mm high

As far as we have been able to determine this is the sole surviving instrument of this type.

For further details see Vermeulen, DJ. 2000. The Historical Interest Group re-discovers Popov. Elektron 17(6), June:13.

The instrument is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​

THE FIRST INTEGRATED CIRCUIT

In the 1920s the German manufacture Loewe Radio produced a series of receivers in which several valves and their coupling components were assembled in a common envelope. The only additional items required were the tuning inductance/reaction coils and the tuning capacitor seen in the illustration. This amplifier integration was not easily achieved as each resistor and capacitor had to be individually encapsulated to ensure that they would not contaminate the vacuum.

The main reason for this surprising innovation was to minimise the German licence fee that was based on the number of valves used in a set.

Dimensions: 186 mm wide x 150 mm deep x 190 mm high

The instrument is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​

THE BEGINNINGS OF ELECTRONICS
The Contribution of the South African Dr HJ van der Bijl

Electronics started in 1907 when the American entrepreneur, Lee De Forest, invented the first electronic amplifying device. He named it the Audion and it was subsequently known as the triode vacuum tube (valve).

De Forest promoted his invention extensively and made a special version for telephone repeater service (right hand side illustration). He persuaded the Western Electric Company (WE) to pay him $50 000 for the exclusive rights to use the Audion in the telephone industry. His original crude device was not suitable for industrial application and WE assembled a team of scientists to develop it into a practical unit.

In 1914 The South African, Dr Hendrik van der Bijl, analysed its performance mathematically and designed practical tubes for use on the first transcontinental telephone circuit linking New York and San Francisco (centre and right hand illustrations).

Dimensions: 50 mm diameter, 75 mm high & 55 mm diameter, 90 mm high

For more information see Vermeulen, DJ. 1998. The remarkable Dr Hendrik van der Bijl. Proc IEEE 86(12), December: 2445-2454.

All three of these unique valves form part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​

ELECTRICAL POWER FREQUENCY CONTROL

Electrical power suppliers were legally required to maintain mains frequency within close limits. Over 24 hours the total number of cycles generated had to be controlled to ensure that synchronous time keeping devices would remain accurate.

From the mid-1920s until they were linked with Eskom the equipment illustrated was used to monitor the Johannesburg supply frequency. The accurate pendulum clock was kept in step with standard South African time by regular corrections. The mains frequency drove a synchronous clock motor and a comparison between this and the clock time was made every 15 seconds and any discrepancy showed as a deviation between the two pointers of the main dial.
The two smaller cl​ock faces showed mains time and clock time respectively and were useful when the deviation exceeded 3 minutes.​
Dimensions: 485 mm wide x 335 mm deep x 1690 mm high
For further information see Vermeulen, DJ. 2001. Mains frequency control. Elektron 18(11), November:29.
The clock is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.


http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com

THE PROTOTYPE TELLUROMETER with its inventor Dr TL Wadley (1950)

The Tellurometer measured distances between 3 and 50 km with an accuracy of 3 parts in 106. Instruments were set up at each of the two required points and the distance between them was calculated from the time taken for a radio signal to travel from one end to the other and back again. Once the terminal stations were established the distance could be measured in less than half an hour where previously, using hand methods, it had taken a team several months to complete the same operation.

The Tellurometer was invented and developed by Dr Trevor Wadley working at the CSIR Telecommunications Research Laboratories and was subsequently manufactured in South Africa.

Dimensions: Dish 440 mm diameter, 360 mm front to back, 470 mm high

By 1971 it had earned over R12 million in foreign exchange. This instrument revolutionised land surveying as it became possible to measure distance as quickly and accurately as measuring angles.

The satellite based Global Positioning System has subsequently produced a second revolution in surveying technology.

The Tellurometer is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​

EARLY X-RAY TUBE Circa 1900

X-rays were discovered by the German Wilhelm Röntgen in 1895. In 1896 primitive equipment was already in use in South Africa. By the end of the Anglo-Boer war there were probably as many as 20 X-ray units in operation.
This tube is typical of early units that depended on a rather poor vacuum of about 10 mPa to produce cathode rays (electrons). The cathode lies on the right hand side of tube with the anode mounted at an angle in the centre of the tube. X-rays were produced when the electrons collided with the anode. Such early tubes produced rather low intensities requiring photographic exposures of several minutes.

Dimensions: 360 mm x 100 mm wide x 320 mm high.

A British supplier, Newton & Co, sold this tube but the manufacturer is unknown.

For further details see Vermeulen, DJ. 2002. Early X-ray equipment: a view from the south. Engineering Science & Education Journ, December 11(6): 231-242. The tube is part of the South African Institute of Electrical Engineers historical collection and can be viewed in Observatory, Johannesburg, South Africa.
http://www.saiee.org.za
Tel: +2711 487 3003
Comments or enquiries:
mppc@mweb.co.za or verdene@iafrica.com​.​

STEAM TURBINE DRIVEN DC GENERATOR​

STEAM TURBINE DRIVEN DC GENERATOR manufactured by Greenwood and Batley Limited at Albion Works in Leeds, England. It is believed t​o have been built circa 1900.

Greenwood and Batley Limited donated this DC generator to the University of the Witwatersrand in Johannesburg.
The university donated it to the enthusiasts of the Rand Society of Model Engineers.
In exchange for spare parts for another DC generator, the Rand Society of Model Engineers gave Greenwood and Batley’s DC generator to ESKOM.
This steam turbine driven DC generator is currently on display at Gold Reef City in Johannesburg.

TECHNICAL DESCRIPTION
DC Generator No. 2535 110 Volts 40 Amps 3 000rpm 4 kW
Steam turbine No. G258 3 000rpm Steam pressure 100 psi 7 BHP
Curtis wheel type​
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