| 摘要 |
PURPOSE:To attain magnetic erasure by providing a rectangular wave output circuit, a pulse generating circuit and a circuit outputting AND pulse of pulses of each circuit so as to obtain several pulses for several periods of vertical oscillation. CONSTITUTION:An astable multivibrator 7 and a vertical output circuit 9 generating a vertical period pulse are provided and an output of an AND circuit 8 is connected to a base of an NPN transistor 10. A relay 3 is operated by the initial pulse and the electric charge of a capacitor 4 is discharged through a coil 6, the relay 3 is released before the oscillation of current is not finished, and one end of the coil 6 is opened. The capacitor 4 is charged through a resistor 5 and the change in the electric charge is ignored during the vertical oscillation period. Then the relay 3 is operated by a 2nd pulse aud the capacitor 4 is discharged through the coil 6 again and since the magnetic energy of the coil 6 and the static energy of the capacitor 4 are the same before one period, the current oscillation is restarted while being once interrupted. Thus, the magnetic erasure for a long period is attained.
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