Automatic water pumping controller with two detection lines

"Electronic News" has introduced many practical automatic water pumping circuits, all of which require more than three water level detection signal lines. Since the water tower and the water pump are far apart, in order to save wires and reduce the difficulty of wiring, I designed an automatic water pumping control circuit with only two signal lines. It is used to control my own water pump, and its performance is stable and reliable. Now I would like to introduce it to you.

Circuit principle:

As shown in the figure: Relay J is used to control the power supply of the water pump, and capacitor C1 is used to eliminate interference on the signal line. IC: NE555 is connected to form a Schmitt trigger circuit, using its hysteresis characteristics to achieve the purpose of holding.

Automatic pumping: When the water level drops below point C, point C is suspended. Pin ② of the IC is lower than 1/3 Vcc, and its pin ③ outputs a high level. The relay is energized and the water pump is started to pump water, and the water level gradually rises.

Intermediate hold: When the water level rises to between point A and point B, resistor R4 is connected in series to the circuit. At this time, the potential at point P is controlled at around 1/2Vcc, and the trigger maintains its original state.

Automatic pumping stop: When the water level rises to point A, due to the small water resistance, the potential of point P is higher than 2/3Vcc, the IC's pin ③ outputs a low level, the relay is powered off, and the water pump stops pumping water. This can achieve the purpose of automatic pumping.

The circuit is simple and easy to make, and generally works without debugging.

Note: Water level detection lines ABC can be made directly from rubber aluminum wires and inserted into the pool. BC is required to be very close but not directly touching. A is the highest water level detection line, and C is the lowest water level detection line.