Voltage controlled oscillator

Claim 1

A voltage controlled oscillator for connection between a source of input voltage and an output frequency utilization means for producing a train of output pulses the repetition rate of which is proportional to the input voltage comprising in combination: a. a capacitor for connection to a source of varying directcurrent potential; b. a current source circuit for charging said capacitor having an input (terminal) coupled to the source of input voltage and being coupled to said capacitor for controlling the magnitude of capacitor charging current in response to the magnitude of the input voltage comprising an operational amplifier Connected as a voltage follower and having first and second input terminals and an output terminal, a transistor having its base coupled to the output terminal of said operational amplifier and having its emitter-collector circuit connected in series between said capacitor and a level of potential differing from that of the source of direct-current potential, said first input terminal of said operational amplifier being coupled to the source of input voltage and said second input terminal of said operational amplifier being coupled to the emitter of said transistor to provide a feedback loop to the operational amplifier whereby the current flowing through said transistor is directly proportional to the amplitude of the input voltage by virtue of said voltage follower operation; c. a comparator circuit having a first input terminal connected to be responsive to the voltage across said capacitor, a second terminal connected to a source of reference potential, and an output terminal, the state of potential of the output of said comparator changing from a first level to a second when the potential at its first input reaches a predetermined level with respect to said reference potential; d. a first bistable switching element having a control terminal coupled to the output of said comparator, said element changing its conductive state in response to a change of state in the output of said comparator; and e. means responsive to the output of said bistable element for discharging said capacitor when the output of said comparator changes from its first state to its second state for returning the output of said comparator circuit to its first state.