This device may come in handy at the cottage or at the farm, as well as in many other cases where control is required and the maintenance of a certain the water level in the tank.
So, when using a submersible pump for pumping water from wells for irrigation, it is necessary to monitor the water level has not declined below the position of the pump. In otherwise, the pump is working at idle (without water), will be to overheat and fail.
Get rid of all these problems, you will help the scheme of the universal automatic the device (Fig.1). It is characterized by simplicity and reliability, as well as provides multi-purpose use (or water lifting drainage).
The circuit diagram are not connected with the body of the tank, which eliminates electrochemical corrosion of the surface of the tank, unlike many previously published schemes of similar purpose.
The principle of the scheme based on the use of the conductivity of the water, which, getting between the plates of the sensor, closes the circuit base current of the transistor VT1. This triggers the relay K1 and its contacts K1.1 enables or disables (depends on the position of 82) pump.
As sensors F1, F2, it is possible to use plates of all metals, not susceptible to corrosion in water. For example, you can use old stainless razor blade (Fig.2).
