BELLSET No. 41
Wooden cased Bellset for use with with Telephone No. 310 on shared service separate metering lines. Introduced circa 1946.
The Bellset No. 41 was used on Party Lines to stop bell tinkle on one of the users, when the other user dialled out. The unit incorporated a full wave rectifier bridge and relay, in a manner that the bell was connected once a burst of ringing current was received. As the relay was slugged (to be slow to operate), it did not respond the the spikes caused by dialling.
In 1947 the Thermistor was invented. This was a miniature device that effectively made the Bellset No. 41A redundant, because the Thermistor could be incorporated into any size of phone. The Thermistor was used to stop bell tinkle.
Bellset includes (1956):-
Circuit diagram - N541.
Last revised: August 25, 2022