| 摘要 |
PURPOSE:To apply selectively an erasure current to plural FE heads by connecting parallel resonance circuits comprising each of plural FE heads connected in parallel with a capacitor in series and setting each parallel resonance frequency unequal so as to use a single channel transmission line. CONSTITUTION:FE heads 4, 6 connected respectively with parallel resonance capacitors 5, 7 are mounted on a rotary drum, the parallel resonance circuits are connected in series and connected to a rotary coil of a rotary transformer 3. An oscillator 1 of an erasure current source is connected to a stator coil of the rotary transformer and an erasure current is applied through a single channel transmission line. Resonance frequencies fI, fII are not equal because each resonance frequency of the parallel resonance circuits depends on the FE heads 4, 6 and the parallel capacitors 5, 7 and the oscillator 1 gives an output while the resonance frequencies fI, fII of the resonance circuit are changed over.
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