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Telegraph Relay - Creed, Polarized, 1920s Reg. No: ST 029331
- Relay used at telegraph receiving stations, particularly those operating on long connecting lines. Often signals received over long lines were too weak to operate the receiving instruments directly so the relay served as a very sensitive switch to connect a local battery to the receiving instruments.
A polarized relay incorporated a permanent magnet in its design. Because this type of relay depended completely on magnetic effects, it was faster and more sensitive in operation than a non-polarized relay which incoporated a mechanical return spring.
- Black-painted vertical cylindrical metal case enclosing relay mechanism mounted on circular plastic base. Hinged cap at top of cylindrical case. Projecting Mark/Space control knob at base of case.
|Dimensions:||185 mm (Height), 128 mm (Width), 134 mm (Length)|
|Tagged with:||telegraphy, electrical relays|
|Themes this item is part of:||Telegraphy Collection, The Australian telegraph network 1854-1877, Information & Communication Collection|
|Inscriptions:||Top of circular base embossed: "CREED & Co, LTD LONDON TYPE1927 RELAY" and: "U.S.A. PAT. 1552676 BREVETTE S.G.D.G."
Underside of base embossed: "MADE IN ENGLAND"
Plate on side of cylindrical case engraved: "S123/27 C3000/38"
Plate on side of base engraved: "S123/27 C3000/42"
|Manufacturer:||Creed & Co, London, England, Great Britain, 1920-1929|