JPS6455706A - Magnetic recording output circuit - Google Patents

Abstract

PURPOSE:To prevent the generating of spike noise due to the switching of recording and reproducing without causing a DC current to flow at a primary coil of a rotary transformer by connecting a circuit which becomes the impedance of the resistance which is small at the time of recording and large at the time of reproducing, between an output transistor (Tr) for recording and a power source. CONSTITUTION:To the control electrode of an output Tr2 of a magnetic recording output circuit, a recording signal superimposed to a bias voltage is impressed, and the Tr2 and an impedance circuit 4 are serially connected between a power source +B and a ground potential. To the connecting part of the Tr2 and the circuit 4, one edge of the primary coil L1 of a rotary transformer 1 connected to connect other edge to a ground potential and the input of a reproducing pre-amplifier 3 are connected through a coupling capacitor C1. Without causing a direct current bias current to flow at the primary coil L1 of the rotary transformer 1, the generation of the spike noise is prevented by the switching of the recording and reproducing.