Circuit for independently adjusting frequency deviation of a VCO

摘要

A circuit for controlling the application of a signal source to a variable frequency oscillator is disclosed in which the width of frequency deviation and the lower limit frequency of the modulated signal can be set independently of each other. The emitter of a first transistor is connected to a first voltage source through a first resistor. Its base is connected to a signal source through a capacitor, and also to a second voltage source through a switch circuit. The base of a second transistor is connected to the second voltage source and its emitter is connected to the first voltage source through a variable resistor. The emitters of the first and second transistors are connected with each other by a third resistor. The collector current of the second transistor is supplied to a variable frequency oscillator.