Voltage follower circuit for use in power level control circuits

Claim 1

In an electric power control system of the type including a load power control circuit for varying the level of power from a power source to a load according to the value of a variable control impedance applied across control terminals of said load power control circuit, said load power control circuit of the type providing at its control terminals a voltage varying in response to the value of the variable control impedance, a voltage follower circuit having a pair of input terminals between which may be connected to the variable control impedance and a pair of output terminals to which may be connected the control terminals of a plurality of said load power control circuits in a ganged configuration so as to allow control of a plurality of individual loads with a single variable control impedance with substantially unchanged control characteristics, comprising a) a voltage source; b) a resistor in series connection with the voltage source across the voltage follower circuit input terminals; c) a variable output impedance having its output terminals forming the output terminals of the voltage follower circuit and an input terminal for controlling the impedance between the variable output impedance output terminals, said output impedance value increasing as the input terminal voltage decreases and said output impedance value decreasing as the input terminal voltage increases; and d) voltage sensing means receiving as a first input the voltage across the variable output impedance output terminals and as a second input the voltage across the voltage follower circuit input terminals, for providing an output voltage signal to the input terminals of the variable output impedance representative of the difference between the voltages of the first and second inputs of the voltage sensing means.