| 摘要 |
PURPOSE:To prevent information recorded on a magnetic recording medium from being destroyed owing to switching between recording and reproduction by providing an impedance conversion circuit to the recording/reproduction switching circuit of a magnetic head and eliminating variation in DC potential nearby a switching point during recording and reproduction. CONSTITUTION:A changeover switch 8 is placed at a side 'R' for recording and recording information inputted from an input terminal 1 to the magnetic head 5 is recorded. Further, the potential at a point A is Vcc/2 even during reproduction and the base potential of a transistor(TR) Q4 is the DC potential Vcc/2 because of a time constant R9XC5 which is much longer than the information. Further, the emitter potential of a TR Q4 is also the Vcc/2 DC potential and impedance of the circuit including the TRs Q3 and Q4 is much smaller than the impedance of the magnetic head 5, so even if the changeover switch 8 changes from the side 'R' to a side 'P', the potential difference across a capacitor C3 does not vary, thereby flowing none of the current due to them flows to the magnetic head 5. |
