Power sharing switching circuit
First Claim
1. A power selection system comprising:
- (A) at least one D.C. power source (18) having an output terminal (32);
(B) a common terminal (26);
(C) at least one first switching means (30) coupled between said output terminal (32) and said common terminal (26) and responsive to a first signal for connecting between said output terminal and said common terminal and responsive to a second signal for effecting a disconnection between said output terminal and said common terminal;
(D) second switching means (72, 50,
42) responsive to the electrical state of said output terminal and a signal source for providing said first signal to said first switching means;
(E) said signal source (68, 52,
62) comprising third switching means (68,
52) responsive to the signal state of said common point (26) for providing a power level from said source to said second switching means, the power level provided to said second switching means decreasing as the voltage at said common terminal increases, whereby said first switching means (30) effects said connection between said output terminal and said common terminal; and
(F) unidirectional flow means (55) connected across said first switching means (30) and poled to conduct current flow in the same direction as said first switching means but having a voltage drop significantly greater than said first switching means, said unidirectional current flow means providing biasing power to said second and third switching means prior to conductive operation of said first switching means and in the absence of any initial potential on said common point.
2 Assignments
0 Petitions
Accused Products
Abstract
A switching circuitry for coupling the power output of one of a plurality of power supplies to a keyboard. In this disclosure, a switching transistor of the circuit is coupled to switch power from a power supply output to a common point to which a plurality of like circuits and a keyboard are coupled. A differential amplifier having one input coupled to the common point and another input coupled to the power output of the respective power supply compares voltage on the common point to the voltage of the power supply. If the power supply voltage is higher than the voltage on the common point, the amplifier provides an enabling signal to the transistor, coupling power from the power supply to the common point. Conversely, if the voltage on the common point is higher than the voltage of the power supply output, the amplifier provides a disabling signal to the transistor, decouping the power supply output from the common point. Diodes shunt the switching transistors in order to provide power to the differential amplifiers.
16 Citations
2 Claims
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1. A power selection system comprising:
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(A) at least one D.C. power source (18) having an output terminal (32); (B) a common terminal (26); (C) at least one first switching means (30) coupled between said output terminal (32) and said common terminal (26) and responsive to a first signal for connecting between said output terminal and said common terminal and responsive to a second signal for effecting a disconnection between said output terminal and said common terminal; (D) second switching means (72, 50,
42) responsive to the electrical state of said output terminal and a signal source for providing said first signal to said first switching means;(E) said signal source (68, 52,
62) comprising third switching means (68,
52) responsive to the signal state of said common point (26) for providing a power level from said source to said second switching means, the power level provided to said second switching means decreasing as the voltage at said common terminal increases, whereby said first switching means (30) effects said connection between said output terminal and said common terminal; and(F) unidirectional flow means (55) connected across said first switching means (30) and poled to conduct current flow in the same direction as said first switching means but having a voltage drop significantly greater than said first switching means, said unidirectional current flow means providing biasing power to said second and third switching means prior to conductive operation of said first switching means and in the absence of any initial potential on said common point. - View Dependent Claims (2)
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Specification