Author Topic: Proper line-in wiring for your telephone  (Read 14566 times)

Offline AE_Collector

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Re: Proper line-in wiring for your telephone
« Reply #30 on: March 03, 2018, 11:25:31 AM »
Its still fuzzy but the tube was across the line and the ringer connected to the Tube? Was this to improve the line quality by getting the ringers off the line? Were there different tubes in other parties phones with the tube recognizing when the appropriate ringing was there for the party?

Terry

Offline kb3pxr

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Re: Proper line-in wiring for your telephone
« Reply #31 on: March 06, 2018, 11:18:32 AM »
Its still fuzzy but the tube was across the line and the ringer connected to the Tube? Was this to improve the line quality by getting the ringers off the line? Were there different tubes in other parties phones with the tube recognizing when the appropriate ringing was there for the party?

Terry

I'm not too well versed in these circuits, but these weren't that complicated. The only difference between parties was the wiring. There were also solid state variants.

These circuits were effectively diode circuits. If you were tip positive party, ring parties wouldn't reach the circuit and negative tip would be blocked by the tube (or diodes). When positive tip was rung, the tube conducted and allows the current to reach the bell.

In fact, the circuit is so simple that in the Bell System, the test for a bad tube was to simply short the tube pins with a screwdriver and have a ringing test ordered from the CO (either test desk special test number). If the tube was bad the bell would ring with shorted terminals, but not with the circuit normal, if the tube was good (or there were multiple faults), the bell would not ring.

Of course repair service couldn't just jump the bell out of the circuit as the positive and negative selectivity would be lost and other problems such as too many ringers on the line could also result.