TREE

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...

Pumping of water into a tank is accomplished by motor operation. When the tank is about to be full with water, the motor pump is about to stops to operate. When the tank is about to be emptied, the motor pump will start to operate. Float Switch Motor Pump Control Operation Figure below (A) shows a tank half filled with water. The motor pump M at idle condition. Water flows out from the gate valve L. Lever C is tilted downward to the right because of the weight W1. Mercury B is at the right position inside the glass container A. the metal rods X and Y inside the sealed glass container A are at open condition. Float bulb K float over the water J inside the tank. Float bulb K goes down as the water drops down. (A) Water is withdrawn from the tank. Water level drops downward. When the water level drops down beyond the stopper E, Figure below (B) the stopper E prevents float bulb K to go down further. When the water level goes down further weight W2 the effect of the combined weight of flo...

The circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries.  The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery. This should be enough current to fully charge a pack of 2500ma-hour cells in about 36 hours.  The circuit uses a single 74HC14 hex Schmitt trigger inverter in conjunction with a voltage doubler charge pump circuit. Source: DiscoverCircuits