| 摘要 |
PURPOSE:To cope with both 'constant voltage output' and 'voltage changing output' by using an output circuit formed, by inserting a switching transistor (TR) between a power supply and a circuit network between collectors of a couple of differential TRs so as to apply the control by an external signal. CONSTITUTION:When a transistor (TR)Qs is a switching TR, and its control input terminal CNT is brought into a low level to turn off the TR, then 'constant voltage output' is obtained. On the other hand, a signal in phase to a signal inputted to a signal input terminal IN is inputted co the control input terminal CNT and the TR Qs is turned on, the TR Qs is turned on, and when the voltage at the control input terminal is nearly equal to a power voltage Vcc, then the cathode level of the diode D2 is Vcc-VF, where VF is a base- emitter voltage of the TR Qs, and since the anode does not reach a votlage Vcc, then the diode D2 is not conducted at any case. Thus, the collector of a TR Q2 is separated substantially from a resistor other than the road resistor RL2 and a diode circuit network and 'voltage change output' is obtained.
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