| 摘要 |
PROBLEM TO BE SOLVED: To avoid consumption of useless power and to prevent overheat of a transistor(TR) when a DC voltage at an input terminal is comparatively high by eliminating a delay in an interrupting current of the TR that amplifies a current. SOLUTION: An OFF improvement means 10 comprising a 3rd TR 11, a Zener diode 12, a current limit resistor 13, and a capacitor 14 is provided between a 1st TR 1 and a 2nd TR 4. When a trailing part of a pulse signal T is given to a base of the 2nd TR 4, the 2nd TR 4 is nonconductive and a voltage having been charged in the capacitor 14 is discharged in a direction from a base of the 3rd TR 11 to its emitter, a 2nd resistor 3 and the capacitor 14, and the 3rd TR 11 is conductive. In this case, no current flows to the Zener diode 12. Since the emitter and the base of the 1st TR 1 are terminated by a low impedance, a delay in an interrupting current due to a storage effect of the 1st TR 1 can considerably be improved.
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