Electronic vibrato system

Means for modulating the frequency of an analog signal comprising:

• first and second identical multi-stage, clock controlled, analog shift registers, each having a signal input, a signal output, and a clock input, each said shift register being operative to sample the value of a signal at its signal input and to shift said sampled signal to its signal output, stage by stage, under control of a clock signal applied to its clock input;
• means responsive to said analog signal for dividing said signal into upper and lower frequency bands, said upper frequency band being applied only to said first shift register and said lower frequency band being applied only to said second shift register;
• means for generating a clock signal, said clock signal being applied to said clock inputs of said first and second shift registers;
• and
• means for modulating the frequency of said clock signal at a rate equal to the desired rate of modulation of said analog signal.

In a system having an analog input and output in the audio frequency range, means for producing a vibrato effect comprising:

• first and second multi-stage analog shift registers, each having a signal input, a signal output, and a clock input and being operative to sample the value of a signal applied to its signal input and to shift said sampled signal to the signal output thereof, stage by stage, under control of a clock signal applied to its clock input;
• means responsive to said analog input for dividing said audio frequency range into upper and lower frequency bands;
• first means for applying said upper frequency band only to said signal input of said first shift register, said signal output of said first shift register providing a portion of said analog output;
• second means for applying said lower frequency band only to said second shift register, the signal output of said second shift register providing a portion of said analog output;
• means for generating a clock signal;
• third means for applying said clock signal to said clock input of said first shift register;
• fourth means for applying said clock signal to said clock input of said second shift register;
• and
• means for modulating the frequency of said clock signal at a subaudio frequency rate.

Means for modulating the frequency of an analog signal comprising:

• a multi-stage, clock controlled, analog shift register having a signal input, a signal output, and a clock input, said shift register being operative to sample the value of a signal at its signal input and to shift said sampled signal to said signal output, stage by stage, under control of a clock signal applied to said clock input, said analog signal being applied to said signal input of said shift register;
• means for generating a clock signal, said clock signal being applied to said clock input of said shift register;
• means for modulating the frequency of said clock signal at a rate equal to the desired rate of modulation of said analog signal;
• switch means operatively coupled to said clock signal frequency modulating means for switching the modulating frequency between first and second different frequencies;
• and
• delay means interposed between said switch means and said clock signal frequency modulating means for controlling the rate at which said modulating frequency changes from said first frequency to said second frequency.

Means for modulating the frequency of an analog signal comprising:

• first and second identical multi-stage, clock controlled, analog shift registers, each having a signal input, a signal output, and a clock input, each said shift register being operative to sample the value of a signal at its signal input and to shift said sampled signal to its signal output, stage by stage, under control of a clock signal applied to its clock input;
• means responsive to said analog signal for dividing said signal into upper and lower frequency bands, said upper frequency band being applied to said first shift register and said lower frequency band being applied to said second shift register;
• means for generating a clock signal, said clock signal being applied to said clock inputs of said first and second shift registers;
• means for modulating the frequency of said clock signal at a rate equal to the desired rate of modulation of said analog signal;
• and
• frequency dividing means for dividing the frequency of said clock signal prior to application to said clock input of said second shift register.

In a system having an analog input and output in the audio frequency range, means for producing a vibrato effect comprising:

• first and second multi-stage analog shift registers, each having a signal input, a signal output, and a clock input and being operative to sample the value of a signal applied to its signal input and to shift said sampled signal to the signal output thereof, stage by stage, under control of a clock signal applied to its clock input;
• means responsive to said analog input for dividing said audio frequency range into upper and lower frequency bands;
• first means for applying said upper frequency band to said signal input of said first shift register, said signal output of said first shift register providing a portion of said analog output;
• second means for applying said lower frequency band to said second shift register, the signal output of said second shift register providing a portion of said analog output;
• means for generating a clock signal;
• third means for applying said clock signal to said clock input of said first shift register;
• frequency dividing means for dividing the frequency of said clock signal and for applying said frequency divided clock signal to said clock input of said second shift register;
• and
• means for modulating the frequency of said clock signal at a subaudio frequency rate.