Gte Lenkurt Electric (canada) Ltd.

Ael Microtel, Ltd.

Edward T Ball

John E White

An input signal is applied to the inverting input of a class B amplifier and to the input of a limiter circuit. The square wave signal from the limiter is applied to the input of a switching amplifier which drives this amplifier between V and ground at the switching rate established by the input signal; thereby, obtaining a power control signal. The power control signal is applied to one terminal of a load and to the non-inverting input of said class B amplifier. Ignoring the input signal to the amplifier, this switches the output of the class B amplifier between V and ground at the same rate and in phase with the output from the switching amplifier. The gain of the input signal path in the amplifier is such that the input signal will just drive the output between V and ground. The switching action of the power control signal in combination with the input signal then causes the output signal across the load to have the same characteristic as the input signal but with a peak-to-peak amplitude of 2V.

Switch mode - class B power amplifier

Operating power for line signal repeaters is fed over a transmission cable pair (signal line) which is susceptible to lightning strikes and, thus, to longitudinally induced currents in the DC power feed circuit. A symmetrical non-linear power regulator is connected between the signal line and the line signal repeater, and includes a high current shunt regulator which bypasses excessive induced currents. By so doing the adverse effects of these induced currents on the operation of the line signal repeater is minimized. A shunt voltage regulator provides the line repeater with a constant operating voltage when the line current (DC line power feed current plus induced currents) is greater than the minimum required bias current. When the potential at input terminals of the power regulator exceeds a predetermined value, a portion of the excess current is conducted through a blocking diode to charge an energy storage device. But, when the DC line power feed current and the induced current oppose each other the energy stored in the energy storage device is used to supplement the power feed current to just maintain the required repeater voltage, until the potential decreases below the operating voltage.

Power regulator for use with line signal repeaters which are remotely

Apparatus for reducing the susceptibility of line signal repeaters to induced currents includes a zener diode/diode stack which provides the line repeater with a constant voltage drop when the DC line current is above the minimum required bias current. When the DC input current plus an induced component from the line exceed the load requirements of the repeater, the excess current is conducted through a blocking diode to charge an energy storage device. But, when the DC input current and the induced component oppose each other, the energy stored in the energy storage device is used to supplement the input current to just maintain the required repeater voltage.

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Coquitlam, Canada

Edward T Ball