The device is designed to automatically maintain the water level in the specified limits. Such a controller is very convenient to control the electric pump, pumping ground water from basements and other underground premises.
In the basement, in the deepest place dig metal tank and mounted therein two level sensors: one is lowered almost to the bottom, second set near the upper edge of the tank. The tank and the sensors connected to the electronic unit (see diagram).
Top tank cover grille. Dirt water accumulating in the tank, after a while will reach the lower end sensor E1. At this point, on the control electrode of SCR VS1 appears opening energized, it opens and works relay K1. The Contacts K1.1 it connected in parallel with the sensor, the second sensor E1 E2. The Contacts K1.2 (not shown), the relay will switch the pump motor, which will start pumping water from of the tank.
After some time the water level drops below E2 and sensor opening the voltage of the control electrode of SCR will be removed. After that nearest point of crossing the "zero" line voltage of the SCR is closed turning off the pump. Followed by slow accumulation of water up to the level of E1 - and the cycle repeats.
The sensor is a plate made of stainless steel strip thickness of 2 mm, mounted on a holder made of insulating material with a low degree moisture absorption (ebonite, polyethylene, PTFE, rubber, etc.). The tank also preferably be made of stainless metal.
Relay K1 - RAS, passport RS4.524.203 (or other suitable voltage positives, preferably with more powerful contacts). The transformer T1 is any, power 5...8 watts with a secondary winding voltage of 15 V.
The described controller can be used for various purposes and in folk the economy, it is only important that the working fluid is electrically conductive.
Author: V. goldsmith, Donetsk