. The Bell System technical journal . ao o3 ?5 oo CO Tfit: tVpS pi cAflHiEft SYSTEM 361 keyers which, function independently, depending on the nature of theringing signal. The 2,500-cycle keyer responds to 20 cycles applied toeither the tip or ring conductors. The gating diode is back biased about3 volts to prevent random noise peaks from operating it. The l,7oO-cyclekeyer responds to any ringing signal applied to the tip circuit. A diodeoppositely poled to the gating diode has a high breakdown so that anyreverse voltage peaks leaking through to it will not open the gate. The1,150-cycle keyer
. The Bell System technical journal . ao o3 ?5 oo CO Tfit: tVpS pi cAflHiEft SYSTEM 361 keyers which, function independently, depending on the nature of theringing signal. The 2,500-cycle keyer responds to 20 cycles applied toeither the tip or ring conductors. The gating diode is back biased about3 volts to prevent random noise peaks from operating it. The l,7oO-cyclekeyer responds to any ringing signal applied to the tip circuit. A diodeoppositely poled to the gating diode has a high breakdown so that anyreverse voltage peaks leaking through to it will not open the gate. The1,150-cycle keyer responds to 20-cycle ringing voltage superimposed witheither plus bias voltage applied to the tip or with minus bias voltageapplied to the ring conductor. At the remote terminal the signaling tones are each selected at theoutput of the expandor by tuned circuits, amplified by a transistor andrectified to activate relays controlling the customer ringing. The 2,500-cycle tone interrupted at a 20-cycle rate controls the remote ringing g
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
