| 摘要 |
PURPOSE:To attain a miniaturization of a device and its moderate price by connecting a self-arc extinguishing element controlled by the inversion relation to another self-arc extinguishing element between main terminals which are not connected to the base of a bipolar transistor and the emitter of a bipolar transistor made of a self-arc extinguishing element. CONSTITUTION:One self-arc extinguishing element controlled by the inversion relation is connected to another self-arc extinguishing element 30 between the main terminals which are not connected to the base of the bipolar transistor 1 and the emitter of the bipolar transistor 2 made of a self-arc extinguishing element. Instead of a Zener diode, the 2nd self-arc extinguishing element 30 with a low on voltage is used, and turned on and off by the inverse relation of the 1st self-arc extinguishing element 2 connected to the emitter of the bipolar transistor 1, whereby a voltage impressed when the 1st self-arc extinguishing element is off can be below the low on voltage of the 2nd self-arc extinguishing element 30. Thus, since a low pressure-resistant element can be used as the 1st self-arc extinguishing element, the circuit can be scaled down at a moderate cost.
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