"Newsletter" has introduced a variety of practical automatic pumping circuit, these circuits require three or more of the water level detection signal line. Cooling towers and water pumps for the distance, in order to save wire and reduce the frame lines difficult. I designed a line of only two signal automatic pumping control circuit. Used to control its own water pump, performance, reliability, are presented to you.
Figure in the relay J is used to control the pump power supply, capacitor C1 is to eliminate the interference of the signal line. IC: NE555 connected as a Schmitt trigger circuit, the use of its hysteresis characteristics to maintain a purpose.
Automatic pumping: When the water level dropped below the C point, C point vacant. IC’s ? feet below 1/3Vcc, its pin output high, pull the relay is energized to start the water pump pumping the water level gradually rise.
The middle to keep: When the water level rose to between A point to B point, the resistance R4 is string access circuit, this time point potential control 1/2Vcc P about the state of the trigger to keep the original unchanged.
Pumping from the stop: When the water level rises to point A, due to less water resistance, P point potential than 2/3Vcc, IC’s pin output low, the relay power, water pumps stop pumping. This can be achieved automatically pumping purposes.
The circuit is simple, easily produced, can work normally without debugging.
Description: The water level can be directly detected line ABC made of aluminum with rubber, into the pool, BC requirements are very close but not direct contact. A is the highest water level detection line, C is the lowest water level detection line