Magnetic Tape Recorder with a Reproducing Head Using Parametric Oscillation for Low Frequency

This paper describes a magnetic tape recorder for low frequencies which uses a parametric reproducing head. The head is based on parametric oscillation in a resonant circuit comprised of a head and a variable capacitance in order to reproduce low frequency signals, something difficult to achieve by conventional methods. The output voltage is dependent only on the magnetic field of the input recording signal and is independent of the frequency of that signal. Consequently, the equipment has an output proportional to the input and a constant frequency response from zero to about 100 Hz. Here, the operation of the equipment is analyzed theoretically and its advantages are described.