hello friends ,i have developed a simple but efficient water level monitor and pump controller for OVER HEAD TANK.it has an added feature of monitoring the water level in sump or well if needed.i developed it mainly for my home,where i need to pump water from a small tank in my basement to a large OHT(over head tank).
i have serached for a circuit like this for weeks,but couldnt find one.so i designed it using CMOS 4001 & 4011.for noise immunity i have used 4093 schmidt trigger IC instead of 4011(i have only a broad idea about all these jargons ,iam not sure if its appropriate)..the pin numbers are clearly shown to make design idea to practical circuit easier.
The input to the logic gates can be either through a float switch or signal through a pair of conducting probes (which need to be amplified using transistors).from circuit its clear that it works on S-R latch feture of logic gates.i have provided visual output for the staus monitoring(it works in a limited way though)of tanks without extra wiring.the building cost for the circuit is less than 10 US$ including the mechanical relay and delay circuit(delayed turn -on) used with it.
Out put from logic circuit is amplified using a darlington pair to drive a 100ohm 6V relay.this relay is used to switch on a delayed turn on relay circuit which switch on the main terminal to pump.(please see the pdf attchement).I used two relays for high voltage isolation as an extra protection.
the probes are made of stainless steel wire (from paper clip)mounted on PVC pipes.wires are soldered to steel pins and joints made water tight with sealent adhesive.(inviting ideas for better as well as cheaper probes) .the central control circuit can work with input from Ultrasonic level sensor probes/IR level sensors as well as float switches and simple moisture probes.just modify slightly according to each type of input.
After 2 months of continuous use the only one problem i have faced so far is sometimes if you switch one and off the circuit rapidly after 3 or 4 attempts it will turn on the pump regardless of water level status.but if the water level in upper tank is at it maximum or in sump if it is below lower limit it will turn off pump immediately(anyway pump will not run dry or no overflow,it fullfill the purpose) )
more details are there in the pdf file.
special thanks for logism for designing this circuit.if you are into simulation of the circuit please get the logisim from website
http://ozark.hendrix.edu/~burch/logisim/
i am ready to send the .*crc file if u are interested in testing and simulation.it is very easy to construct the circuit from the bmp image in the previous post. the site restrictions prevent me from uploading the file.
download link to logisim http://ozark.hendrix.edu/~burch/logisim/download.html
I am inviting attention of all experienced members to please go through this circuit and provide with ideas to improve the same also please point out the mistakes i made.thank you.

Attached Images

PUMP CONTROLLER.gif (14.7 KB, 20 views)

Attached Files

sensor probes &DELAYED TURN ON RELAY.pdf (155.3 KB, 16 views)

 

special thanks for logism for designing this circuit.if you are into simulation of the circuit please get the logisim from website
http://ozark.hendrix.edu/~burch/logisim/
i am ready to send the .*crc file if u are interested in testing and simulation.it is very easy to construct the circuit from the bmp image in the previous post. the site restrictions prevent me from uploading the file.
thank you.
download link to logisim http://ozark.hendrix.edu/~burch/logisim/download.html

 

in the diagram
UL=UPPER TANK LOWER PROBE
UU=UPPER TANK UPPER PROBE
LL=LOWER TANK(SUMP)LOWER PROBE
LU=LOWER TANK(SUMP) UPPER PROBE
RED led turns on when lower tank is empty and remains on till water reaches upper sensor level.
green led turn on when water reaches upper probe of upper tank& after that when water remains between two sensor probes in upper tank.
invites methods to make circuit more immune to noise.and other possible errors..