| 摘要 |
PURPOSE:To form a recording and reproducing circuit, whose operation can be switched to the recording operation and the reproducing operation by the switching operation of a switch provided at the outside of a signal light through which signals recorded and reproduced by a magnetic head are transmitted, with a small number of constituting parts. CONSTITUTION:A mode switching control signal is inpressed from a control input terminal 32 to the base of a switching transistor (TR) 28A of a bias switching circuit 28. Said switcing TR28A is turned off in the recording operation mode and is turned on the reproducing operation mode, and a voltage VZ at a connection middle point A is impressed as a bias voltage to the base of the first- stage amplifying TR24 of a reproducing amplifier 23 through a primary coil 31P of a rotary transformer 31. Thus, the recording operation where magnetic recording is performed with a magnetic head 21 by the recording current from a recording amlifier 22 and the reproducing operation where the reproduced signal from the magnetic head 21 is amplified by the reproducing amplifier 23 are switched. |
