Push-button dial circuit
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United States of America Patent
Stats
-
Jan 4, 1983
Grant Date -
N/A
app pub date -
Sep 12, 1980
filing date -
Sep 14, 1979
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A push-button dial circuit having a low DC resistance and a high output impedance. An oscillator for generating a multi-tone dial signal is connected through a buffer transistor to terminals for coupling the multi-tone dial signal to a subscriber's line. The terminals also supply a DC power source current to the dial circuit. A constant voltage circuit is connected to the oscillator to stabilize the DC current supplied to the oscillator, and a reactance transistor circuit is connected between the terminals and the oscillator for defining a DC supply path from the terminals through the reactance transistor circuit to the oscillator. The reactance transistor circuit includes a transistor having a capacitor and a resistor respectfully connected across the base-emitter path and across the base-collector path of the transistor.
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