US 4,380,688 A · Telephone ringing range extender

Abstract

A circuit arrangement utilized for extending the ringing range of a single party telephone service utilized on long rural line loops where the ringer and a blocking capacitor of the subscriber's telephone instrument has been connected across the tip and ring electrical conductors of the loop includes; a pair of terminals connected to the tip and ring conductors of the subscriber's line, a zener diode connected from one of the electrical conductors with a capacitor connected in parallel therewith. A switching device is connected in series with the parallel connection of the zener diode and capacitor providing a current path to a reference ground. A circuit device responsive to the application of the ringing signal voltage between a reference ground and the other electrical conductor of the subscriber loop activates the switching means to provide a relatively low impedance current path effectively removing one of the electrical conductors from the subscriber loop of the ringing circuit, therefore enabling the ringing voltage to be extended over a loop which is double the length of the normal rural subscriber loop.

Claims11

Dependent claims

A ringing range extender for single party telephone service on long rural line loops wherein the ringer and a blocking capacitor of a subscriber's telephone instrument has been connected across the tip and ring electrical conductors of said loop comprising, in combination:

(a) first and second terminals adapted to be DC coupled to said tip and ring conductors of said subscriber's line connecting said subscriber's telephone instrument to a central office to provide for the application of the central office battery and AC ringing signal voltages across said terminals;
(b) semiconductor, breakover means;
(c) capacitor means, connected in parallel with said semiconductor breakover means, one end of said capacitor means being connected to one of said subscriber loop conductors;
(d) switching means, said switching means being connected between a ground reference and the other end of said capacitor means for providing a relatively low impedance DC series current path from said one of the subscriber loop conductors through said semiconductor breakover means to said ground reference upon activation of said switching means, said switching means providing a relatively high impedance when de-activated;
and
(e) circuit means responsive to the application of a ringing signal voltage from the other of said subscriber loop conductors to said reference ground for providing an activating voltage to said switching means.

3 more elements

A ringing range extender for single party telephone service on long rural line loops wherein the ringer and a blocking capacitor of a subscriber's telephone instrument is connected across the tip and ring electrical conductors of said loop comprising, in combination:

(a) first and second terminals adapted to be DC coupled to said tip and ring conductors of said subscriber's line connecting said subscriber's telephone instrument to a central office to provide for the application of the central office battery and AC ringing signal voltages across said terminals;
(b) a first zener diode having anode and cathode electrodes, said first zener diode anode electrode being connected to one of said subscriber's electrical loop conductors;
(c) a first capacitor, said first capacitor being connected across said zener diode;
(d) circuit means for maintaining said telephone ringer disconnected from a reference ground in its de-activated state, in its activated state said circuit means completing a current conduction current path connecting said zener diode cathode electrode to said reference ground;
(e) a second zener diode;
(f) a second capacitor connected in series with said second zener diode, said second zener diode and said second capacitor being connected between said first and second terminals such that said second zener diode is forward biased by ringing signal alternations of one preselected polarity to rectify the central office ringing signal for supplying rectified ringing signal current to charge said capacitor;
and
(g) a current conducting light emitting device connected in series with said second zener diode and in parallel with said capacitor in a discharge path for said capacitor, said device being in a non-conducting state in which it emits no light when the voltage across said capacitor is below a preselected value, said device being responsive to an increase in the voltage across said capacitor above said preselected value to emit light upon conducting current, said emitted light being coupled to said circuit means for changing it from its deactivated state to its activated state.

5 more elements

Dependencies are inferred from the claim text.

Telephone ringing range extender

Life of this patent

Telephone ringing range extender

Life of this patent

Abstract

Claims11