Voltage controlled multivibrator having variable frequency and duty cycle
AssigneeTimex Corporation
InventorPaul E. Hochstrate
Life of this patent
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Abstract
A voltage controlled oscillator (VCO) to produce a variable frequency and duty cycle output proportional to the applied (input) voltage. The VCO comprises RC charge networks to vary both the frequency and duty cycle of an astable multivibrator with applied voltage variations. The VCO has particular application for low voltage and low frequency operation.
Claims11
A voltage controlled oscillator circuit of the type having an astable multivibrator coupled between two voltage terminals for providing output pulses having a periodicity which varies as a function of the input voltage applied across the voltage terminals, wherein the improvement comprises:
- said astable multivibrator having a first timing network connected between first and second transistors and being responsive to the amplitude of the input voltage, and a first feedback circuit connected between an output terminal of said second transistor and an input trigger terminal of said first transistor for controlling the pulse width of said output pulses;
- and
- means having a second timing network connected to said input trigger terminal and being responsive to the amplitude of the input voltage and the output pulses for controlling the period between the output pulses;
- whereby the periodicity and duty cycle of the output pulses vary as a function of the input voltage.
The combination comprising:
- first and second power terminals for the application therebetween of a varying voltage;
- an astable multivibrator, having first and second transistors, the first transistor has its emitter connected to the first power terminal and its collector connected via a first resistor to said second power terminal and via a first capacitor to the base of said second transistor, the second transistor has its base connected via a second resistor to the second power terminal and its emitter connected to said first power terminal and its collector connected via a third resistor to said second power terminal and via a first feedback circuit to the base of said first transistor;
- an RC charge network, having a second capacitor and a fourth resistor connected in series between said first and second power terminals;
- a discharge network, having a third transistor with its emitter connected to the first power terminal and its collector connected to a common connection between the series connected second capacitor and fourth resistor and its base connected via a second feedback circuit to the collector of said second transistor;
- and
- means connected between said common connection and the base of said first transistor for coupling a voltage developed across said second capacitor to the base of said first transistor.
Dependencies are inferred from the claim text.