| 摘要 |
PURPOSE:To detect surely the position of a liquid level with one liquid level detector, by detecting the peak value of the voltage output signal of one liquid level detector and comparing a voltage division signal with the voltage signal from the liquid level detector. CONSTITUTION:A transformer 7 is connected to a stabilized electric power supply circuit 10 through a rectifying circuit 8 and a smoothing capacitor 9. A liquid level detecting element 2a is connected in series to a limiting resistance 11. An operational amplifier 13 constitutes an impedance converting circuit, and a capacitor 14 holds the output voltage value of the operational amplifier 13 for ten seconds. A peak detecting circuit 15 is constituted with the operational amplifier 13 and the capacitor 14. A voltage dividing circuit 16 divides the output of the circuit 15 by resistances 17 and 18. A comparator 19 compares the output of the voltage dividing circuit 16 and the signal voltage of the element 2a with each other. An output circuit 20 turns on or off an output relay 21 in accordance with the output change of the comparator 19 by a transistor 22. |
