editor
471
edits
Bell wire: Difference between revisions
Be clearer on microfilters. Add table for pin allocation
(Effects of eliminating the tinkling) |
(Be clearer on microfilters. Add table for pin allocation) |
||
|
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.
= BT plug/socket numbering =
This is a complete list of pin usage. Pin 1 is closest to the latch.
{| class="wikitable"
|-
! Function !! Pin number || Notes
|-
| 1 || ||
|-
| 2 || 'B' wire || Used to be guaranteed more negative voltage than 'A' wire
|-
| 3 || Bell wire || To distribute ringing current, and eliminate tinkling
|-
| 4 || Local earth || ''Needed for 'C' wire signalling, which is obsolete''
|-
| 5 || 'A' wire ||
|-
| 6 || 'C' wire || '' 'C' wire signalling is obsolete''
|-
|}
| |||