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'Telephone' Condenser - Marconi, Radio, circa 1908 Reg. No: ST 015469
- Stepped variable capacitor, made by Marconi's Wireless Telegraph Co. Ltd., London, England in about 1908. Used in radio equipment.
The 'telephone' condenser was used by the radio operator to adjust the sound of the detector to their preference or to match the tone of the transmission being received.
It is called a 'telephone' condenser because it connected in parallel across the headphone terminals (headphones were known as 'telephones' in the early days of radio).
The capacity can be adjusted in steps of 50 units from 0 to 350. The unit is a jar (1/900 µF). The wooden case contains tinfoil sheets with mica insulation, fixed in paraffin wax.
Also known as a stepped variable condenser or stepped variable capacitor.
- Wooden box with ebonite top and brass fittings, two terminals and three movable pegs. One peg is broken and is kept in a bag attached to the capacitor.
- Acquisition Information:
- Donation from Amalgamated Wireless (Australasia) Ltd., 1924
|Dimensions:||250 mm (Height), 76 mm (Width), 126 mm (Length)|
|Tagged with:||radios, electronics, electrical condensers, capacitors|
|Themes this item is part of:||Information & Communication Collection, Early radio: transmission and reception, 1900 - 1914|
|Inscriptions:||Metal plate on side of box: MARCONI'S WIRELESS / TELEGRAPH Co Ltd / No 45601 LONDON
On top on brass fittings: 50 100 200
Bottom of box: 45601
|Manufacturer:||Marconi?s Wireless Telegraph Co. Ltd., England, Great Britain, circa 1908|
|References:||Wikipedia. Accessed 12 December 2012. http://en.wikipedia.org/wiki/Jar_(unit)|
This item is part of the following themes: