Widely used; Simple and easy to understand; Easy to use; Standby current 9MA; Working current 40MA Working voltage: DC 12V (DC 10-15V); Standby current: 9MA; Working current: 40MA; Dimensions: 44mm X 29mm X 19mm; Maximum load: 10A/250VAC, 10A/125VAC, 10A/30VDC, 10A/28VDC, 10A/12VDC There are two purposes for connecting the NO and NC ports of the relay: The water pump is connected to the automatic water tower at the COM NC port. The water pump is connected to the COM NO port and automatically pumps water from the water tower. Notes: The probe (wire) is not included in the package. No need to use special probes, use household wires to make probes. For safety, please use a well-isolated DC power supply. Application: Automatic water supply system for household water tower; Aquarium fish tank water changing system; Automatic filling of water tower; Automatic pumping of water tower; Conductive liquid automatic control; Automatic feeding system for poultry and livestock; Farm automatic water supply system; And other occasions that require automatic water supply and water change; Solenoid valve water pump motor automatic control. Interface Description: HIGH: Upper limit probe OUT: output probe LOW: Lower limit probe DC+: positive power supply DC-: Negative power supply NC: Relay normally closed contact COM: Relay common contact NO: Relay normally open contact Working principle (automatic water tower): The water level rises: when the water level is lower than the "low level", the water pump starts to supply water to the water tower; when the water level is higher than the "high level", the water pump stops water supply. The water level drops: When the water level is lower than the "high level", the water pump does not work and the water level continues to drop. When the ter level is lower than the "low water level", the water pump starts to supply water to the water