| 摘要 |
PURPOSE:To simplify a circuit design by constituting the titled circuit of an inexpensive digital input circuit, by connecting a Zener diode and a variable resistor in series to an output terminal of an analog amplifier, and connecting the other terminal of the variable resistor to an earth. CONSTITUTION:A voltage clipping circuit 5 consists of a Zener diode 7 and a variable resistor 8, a cathode of the Zener diode 7 is connected to an output terminal of an analog amplifier 3, and between an anode of the Zener diode 7 and an earth, the variable resistor 8 is connected. An amplifying output of the analog amplifier 3 is supplied to an A/D convertor 4, but when a voltage of the amplifying output exceeds a prescribed level, a current flows to an earth through the Zener diode 7 and the variable resistor 8, therefore, the amplifying output is maintained at a prescribed level or below. |
