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Bell wire: Difference between revisions
Effects of eliminating the tinkling
(Eliminating the tinkling) |
(Effects of eliminating the tinkling) |
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Individual telephones no longer used a bell capacitor, and connected their local bell from the bell wire to the 'A' wire.
By itself this doesn't eliminate the tinkling, until it is arranged that when a telephone goes 'off hook' it also makes a connection between the bell wire and the 'A' wire. This effectively short-circuits the bells of all telephones on the line, and prevents any bell from tinkling during pulse dialling.
== Effects of eliminating the tinkling ==
Telephones designed for the UK will use 3 wires - 'A', 'B', and 'bell'. Their bells will be connected between the bell wire and the 'A' wire. If used in an installation without a bell capacitor or without a bell wire, such telephones won't ring their bells. A good example is a plug-in electronic ringer I have - the BT phone plug has only 2 pins - for the bell wire and the 'A' wire.
The US telephone system is different, and each telephone provides its own bell capacitor - but the US doesn't use pulse dialling any more. Telephones designed for that market will ring without a bell capacitor or without a bell wire.
Some DSL microfilters include a bell capacitor, but some others don't.
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