Low input signal bandwidth compressor and amplifier control circuit

An amplifier circuit comprising:

• a pre-amplifier responsive to a program input signal for providing a compensated signal,
• a filter circuit coupled to receive and automatically filter the compensated signal to provide an output signal and a modified compensated signal, the filter circuit having an automatically adjustable bandwidth, the filter circuit being responsive to a control signal for automatically reducing the bandwidth of the filter circuit in response to reduced values of the control signal to obtain the output signal;
• the filter circuit having,
• an input amplifier for summing the compensated signal and an integrator output signal to provide a modified compensated signal;
• a photocell having;
• a photosensitive resistor and a light emitting diode, the photosensitive resistor being responsive to the light from the light emitting diode for further modifying the modified compensated signal to be an integrator input signal and for coupling the integrator input signal to the integrator input;
• and
• a light emitting diode responsive to the control voltage for illuminating the light sensitive resistor, the resistance of the light sensitive resistor being increased in response to lower values of control voltage;
• and,
• an absolute value circuit responsive to the modified compensated signal for providing a control signal proportional to the amplitude of the modified compensated signal.

An amplifier circuit comprising:

• a pre-amplifier responsive to a program input signal having high, low and mid range frequency signal components for providing a compensated signal, the pre-amplifier having automatic gain control circuitry for balancing the high and mid range signal components;
• a filter circuit coupled to receive the compensated signal, and a control signal and to provide a modified compensated signal, and an output signal, the filter circuit having an adjustable bandwidth, the filter circuit further comprising:
• an input amplifier for summing the compensated signal and an integrator output signal to provide a modified compensated signal;
• a voltage controlled amplifier having an input responsive to the modified compensated signal and the control voltage for providing an integrator input signal current;
• an integrator circuit having an input coupled to receive the integrator input signal current and integrating the integrator input signal to provide an integrator output signal;
• an absolute value circuit responsive to the modified compensated signal for providing a control signal proportional to the amplitude of the modified compensated signal.