PURPOSE: To keep a sound recording bias signal stably against ambient temperature change and to obtain superior sound recording performance and erasing efficiency by controlling a bias oscillation signal outputted from a bias oscillation circuit by a control circuit actuated by DC voltage obtained by rectifying a recording bias signal outputted from an amplifier circuit.
CONSTITUTION: The bias oscillation signal inputted from the bias oscillation circuit 1 to the amplifier circuit 2 is controlled by the control circuit 3 (limiter) actuated by the DC voltage obtained by extracting a part of the sound recording bias signal outputted from the amplifier circuit 2 and rectifying the extracted signal. If the amplifier circuit 2 is actuated as a limiter by holding bare gain in the amplifier circuit 2 sufficiently highly, the sound recording bias is hardly drifted against the peripheral temperature, so that sound recording frequency and erasing efficiency characteristics can be secured without influence due to the ambient temperature.
SANBE MAMORU
SATOU HIROO
| JPS4953018A | 1974-05-23 |