water level indication circuit

The indicator is a water level indication circuit, which is composed of a
water level detection electrode and a voltage comparator in the water tank. When the water exceeds a certain
electrode, the voltage of the corresponding electrode (acted to the ground through the resistance of the water) will decrease. The connected voltage is relatively low and a high level will be output, causing the connected
LED to light up. According to the indications of the four LEDs , thus indicating the level of water level in the water tank.
    For example, when water is injected into the permanent tank and the water level rises to the D electrode, the resistance of the water connects the two electrodes D and E. At this
time, the voltage of the reverse input terminal ② of the operational amplifier IC D is lower than +5 V, pin ① outputs a high level, causing the light-emitting diode VD4 to conduct forward and emit
light, thereby indicating that the water level has reached the D electrical connection. As the water level continues to increase, the detection electrodes C, B, and A in the water tank are connected to the circuit
in sequence , causing the operational amplifiers ICC, ICB, and IC A to output high levels one after another, thus lighting up the diodes VD3, VD2, and VD1 in sequence. , when all four
diodes light up, it indicates that the water tank is full.