| 摘要 |
PURPOSE:To obtain a transistor (TR) switch circuit operated very stably against temperature fluctuation and power supply fluctuation and operated at a low power supply voltage by combining a TR and a Widler constant current circuit. CONSTITUTION:A -X(V) is fed to a signal input section F and a -X+0.4(V) is fed to a signal input section F. A potential between a base and emitter of a Q7 is VBE7=VBE+0.4V>VBE(ON), a current flows through a resistor R3, a base potential of a TRQ9 is selected as VBE9<VBE(ON), a current does not flows to a Q10 and a controlled system circuit is turned off. Then a -X+0.4(V) is fed to the input section F and a -X(V) is fed to the input section. The potential between the base and emitter of the TRQ7 is selected as VBE7=VBE-0.4< VBE(ON) and no current flows to the TRQ7. Thus, a substantial current decided by the Widler constant current circuit flows to the TRQ9, a current flows also to the TRQ10 having the same base potential as that of the Q9 and the controlled system circuit is turned on.
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