| 摘要 |
A telephone ringer isolator includes an electronic switch which enables it to operate at reduced ringer voltages. In the ringer isolator, the central office ringing signal is rectified and voltage doubled across a circuit containing two diodes and two capacitors. The second capacitor is connected across a neon tube. When the voltage across the second capacitor rises to a preselected value, the neon tube is fired to emit light onto a light sensitive resistor which feeds gate current to a Triac to turn the Triac on. The Triac, in turn, grounds the telephone ringer.
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