| 摘要 |
PURPOSE:To prevent the Zener breakdown of the transistors of the initial stage of a read circuit and protect its deterioration by clamping the voltage of the flyback pulse generated in a magnetic head coil at the switching of write current at less than a constant value. CONSTITUTION:At the switching while the write cuurent I1 flowing out from the terminal T1 of a magnetic head coil H is increasing, a flyback pulse is generated at terminals T1, T2 and write current flows in a diode D3. A cathode voltage X becomes lower by the voltage drop component of D3 than the voltage of the terminal T1 and at the peak of the flyback pulse, a peak voltage is applied between the base of Q1 and the anode of a Zener diode Z1. This is clamped by Z1 to protect Q1. Likewise, at the switching while the write current I2 flowing from the terminal T2, the voltage between the bases of Q1, Q2 is clamped by the Zener voltage of Z2 and Q2 is protected. |
