US 4,065,681 AGranted

Voltage storage circuit useful in television receiver control applications

AssigneeRCA Corporation

InventorBilly Wesley Beyers, Jr.

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Abstract

A circuit for storing a DC voltage which may be used to control the volume, brightness, contrast, tint or color characteristics of a television receiver includes a semiconductor switching circuit for selectively coupling a DC voltage to a voltage storage capacitor through a DC impedance path. The DC impedance path is coupled between the inverting and noninverting inputs of an operational amplifier. The output of the operational amplifier is coupled to a utilization circuit to be controlled. A feedback path is coupled between the operational amplifier's output and inverting input to provide negative feedback so that a voltage balance is maintained between the inverting and noninverting inputs and thereby substantially eliminate leakage current flow to or from the storage capacitor through the DC impedance path.

Claims15

Dependent claims

Apparatus for controlling a utilization means, comprising:

a source of fixed potential;
a circuit point;
means for selectively coupling said source of fixed potential to said circuit point;
capacitive means for storing a DC control voltage;
Dc impedance means for coupling said circuit point to said capacitive means to thereby develop said DC control voltage;
operational amplifier means having first and second input terminals and an output terminal, said DC impedance means being coupled between said first and second input terminals;
negative feedback means for coupling said output terminal to said first input terminal, the voltages developed at said first and second input terminals being maintained substantially equal when said negative feedback means couples said output terminal to said one of said first input terminals, and
first switching means included within said negative feedback means for selectively decoupling said output terminal from said first input terminal when said source of fixed potential is coupled to said circuit point.

5 more elements

Dependencies are inferred from the claim text.