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This circuit lets you control a pump, to keep the level of water in a cellar below a certain threshold, for example. Power  is supplied to the pump by a battery that is recharged auto matically when the AC power line voltage is present. Circuit Diagram 12-volt Cellar Drain Pump Circuit Diagram lf the water  level  rises, the electrodes touch the liquid and a current begins to flow. The transistor then conducts and the pump runs. The pump stops when the water level has dropped sufficiently for the electrodes to no longer be in contact with it but not straight away, as the voltage on the transistor gate is maintained for a few seconds more by the 470 ytF capacitor. This makes it possible to ensure  the electrodes are completely clear of the water. The battery is constantly tested by the comparator circuit around the T1071 lC.  lts output drives the  gate of the triac  in the transformer primary circuit via the optoisolator. The transformer secondary charges the battery via the rect...

Water reservoir automatic level control, Simple circuitry - 12V supply By means of a Relay, employed to drive a water pump, this circuit provides automatic level control of a water reservoir or well. The shorter steel rod is the "water high" sensor, whereas the longer is the "water low" sensor. When the water level is below both sensors, IC1C output (pin #10) is low; if the water becomes in contact with the longer sensor the output remains low until the shorter sensor is reached. At this point IC1C output goes high, Q1 conducts, the Relay is energized and the pump starts operating. Now, the water level begins to decrease and the shorter sensor will be no longer in contact with the water, but IC1C output will be hold high by the signal return to pin #5 of IC1B, so the pump will continue its operation. But when the water level falls below the longer sensor, IC1C output goes low and the pump will stop. SW1 is optional and was added to provide reverse operation. Switch...

Cheap Pump Controller Circuit diagram. This simple but effective circuit can be used to control water level in a container. The prototype is used to pump water out of a bucket that collects condensation from a home air-conditioning system. The design is based around a 555 timer (IC1). Although the timer in configured as a mono-stable, it lacks the usual timing capacitor from pin 6 to ground. Instead, a metal probe inserted in the water provides a current path to a second, grounded probe. When the water level in the container reaches a third ("high") probe, the trigger input (pin 3) is pulled low, switching the 555 output high and energizing the relay via transistor Q1. Cheap Pump Controller Circuit diagram:   Cheap Pump Controller Circuit Diagram Once the water level drops below the "low" probe, the threshold input (pin 6) swings high, switching the output (pin 3) low and the relay and pump off. The two 100kΩ pull-up resistors can be replaced with larger values if m...