Abstract: An automatically adjusted equalizer circuit includes an operational amplifier having a parallel resonant circuit, a voltage controlled resistor, and an amplifier output signal monitoring circuit in a feedback path for the adjustable equalizer. The presence of the parallel resonant circuit in the feedback path causes the amplifier gain to vary with frequency. An input signal to the operational amplifier will be distorted depending upon the particular loss characteristic of a telephone wire to which the input is connected. Automatic adjustment of the voltage controlled resistor, and the presence of the resonant circuit, causes the slope of the gain of the amplifier to inversely compensate for the loss characteristic of the particular line in question. Within the variety of lines, each line will have different loss characteristics as a function of length and gauge of the different telephone lines.