| 摘要 |
PURPOSE:To reduce a noise component included in the output signal of a reproduction amplifier circuit in a recording mode and to improve an S/N by short- circuiting and separating a tertiary winding through the use of a three-winding transformer according to the mode. CONSTITUTION:In a write mode a transistor Q4 executes an on-action based on a mode signal S1 to short-circuit the tertiary winding W3, and a current flows. A flux phi3 is generated in the direction canceling a flux phi1 generated in a primary winding W1, and a flux flowing in the core of the transformer 7 comes to zero, thereby protecting a reproduction amplifier circuit 5. On the other hand, in a read mode the winding W3 is separated by the off-action of the transistor Q4, and the flux phi1 interlinks with the secondary winding W2. Besides a reproduction signal is transmitted to a secondary side and given to the reproduction amplifier circuit 5. A protecting circuit part in the circuit 5 is installed by electrically insulating from the circuit 5 in installed by electrically insulating from the circuit 5 in such a way, whereby a noise component caused by the protecting circuit part can be reduced from the output signal of the circuit 5 to improve the S/N. |
