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POST OFFICE RELAY TYPE B No 9534, 1920's

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POST OFFICE RELAY TYPE B No 9534, 1920's

Relay used in telegraphy acting as a form of amplifier for the signal, sensitive coils moved the contacts which controlled equipment that could be powered locally. Post Office Standard Relay B
This relay replaced earlier forms known as A having coils of 100 ohms instead of 200 and being shorter in length. Relay B also sometimes having differential coils (two winding on each coil) It can be of the polarised (see item A0239) or non polarised type the polarised version has a magnet and can be neutralised, as in use with the double plate sounder item A0227, provided it has double throw contacts, which means the pole or tongue T held between M(mark) and S(space) contacts. The relay shown only has a single throw contact, and is not polarised (no Magnet).

Types of telegraphy relays

A Relay earlier version of relay B.
B Relay can be polarised or none polarised. With differential coils. And single or double throw contacts.
C Relay larger magnet and similar to B Relay
D Relay not polarised and does not have differential coils. (Much cheaper).
G Relay later version of Gulstad Relay

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A0252



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