Farm level as shown for the automatic control circuit. The control circuit consists of step-down rectifier circuit, RS flip-flop, solid state relays (SSR) control circuit. One buck rectifier circuit for the entire control circuit to provide VDD = +9 V DC voltage.
When the water tank, if the first power, the voltage on C3 is not due to mutations in leaving IC (555) pin is low, 555 is set, 3 feet high so that the output of the SSR end, the motor D does not run. At this point C3, C4 respectively, through R1, R2 to charge, when the C4 when the voltage charge to 2/3VDD, IC reset, the output pin low so that the internal optocouplers SSR AC 220V voltage connected to the motor D have electricity and running due to pumping. When the water level rose to b when the probe, C4 to discharge through the water, but 555 is still output low, the motor D continue to rotate. When the water level rose when a probe, C3 to discharge through the water, when the C3 potential discharge to the lower 1/3VDD ? feet, the 555 set, 3 feet high so that the output of the SSR end, the motor D door of an inner room without electricity The stops and the level began to decline. When the b probe above the surface when, C4 and charging, repeat the process. This cycle, the liquid to maintain a certain height.
SSR for the exchange of zero-crossing solid state relays, the internal as optocouplers, the control side and output isolation, totally reliable.
In addition to the control circuit for automatic control of farm level, but also on the tower to carry out automatic control of liquid level.