i need a working circuit to construct an automatic water level control...that monitors the water level of my tank automatically...i have tried some online circuits and i didnt get good results...would love the one using 555 timer....

 

What is the reason for a timer, any reason you cannot use a simple float switch?
Max.

 

What is the reason for a timer, any reason you cannot use a simple float switch?
Max.

What is the reason for a timer, any reason you cannot use a simple float switch?
Max.

i cant afford one in my area...would love if could exclude the float switch

 

Hello,

Do you want a min/max or linear mesurement?

Have a look at the following page:
http://njhurst.com/electronics/watersensor/

Bertus

 

Am not talking about measurement..just an automatic on and off switch for the pump

 

i cant afford one in my area.

You could easily make your own using a reed switch and a magnet.

 

Here is one using a 555 timer as a Flipflop, you will need to replace the electrodes after a long period as they will erode away, i would recommend using float switches...

 

https://www.apgsensors.com/reports/...-maintenance-for-your-water-tank-float-switch
Easy to make from PVC tube with a cap at the lower end.
Max.

 

Hello,

An other circuit uses an AC signal for detection:
http://www.simplecircuitdiagram.com/2010/10/19/cd4093-water-level-sensor-detector/

Bertus

 

i cant afford one in my area...would love if could exclude the float switch

Wow.. what area are you from... You can pick up a float for $0.99 shipped
http://www.ebay.com/itm/New-Hot-Sal...617933?hash=item1a196b638d:g:-7wAAOSwImRYT0V0

 

Float switches can be very cheap.
http://www.ebay.com.au/itm/Stainles...1349beb8f94cf7cf841960&pid=100505&rk=1&rkt=1&

Just remember to use it to drive a relay (with a back EMF diode across the coil like in the 555 timer example above) and not switch the motor directly.

But, one like this will switch a motor...
http://www.ebay.com.au/itm/250V-2m-...723897?hash=item51a55d9239:g:DzMAAOSw4GVYM7CD

 

Can i get reliable circuit that could last long

 

Can i get reliable circuit that could last long

Yes use the circuit in post #7, with float switches in post#10, instead of water probes...

 

I dont understand T

Yes use the circuit in post #7, with float switches in post#10, instead of water probes...

Ebay said they cant ship to my location (nigeria)..any other site I could try?

 

If you just need on/off can you not make a simple one as previously suggested? Do you have access to electrical/electronic parts at all?
Max.

 

If you just need on/off can you not make a simple one as previously suggested? Do you have access to electrical/electronic parts at all?
Max.

Yeah..not used to the reeds switch/magnet combination..i succesfully finishedd the circuit and it worked well..its just the probe issue now..i cant just put cables into the water..even if it doessnt conduct highly..any ideas pls...maybe combination of some parts

 

Here is one using a 555 timer as a Flipflop, you will need to replace the electrodes after a long period as they will erode away, i would recommend using float switches...


View attachment 119867

I ignored the diode across the coil and the transistor at the output and it worked fine..so whats the work of those units there?

 

The diode across the coil in the reverse direction is to absorb the voltage spike that is produced when the relay is turned off. When you pass a current through a coil it produce a magnetic field. And then when you switch it off, the field collapses and that works like a generator to produce a voltage spike. The voltage can be quite high and damage other components so it is a good idea to include the diode. Just make sure it is in "reverse" direction, with the cathode to the +ve supply.
Do you have an oscilloscope? If so, have a look at the collector voltage and see how it has a sharp peak when you turn the relay off.
If you were using a switch to turn the relay on and off, it would probably spark. Try with just a relay and a hand held bit of wire and see if you notice a spark. Then put a diode on and the spark will be greatly reduced if not gone altogether.
Yes, include the diode if you want your circuit to last for a long time.

 

Yeah..not used to the reeds switch/magnet combination..i succesfully finishedd the circuit and it worked well..its just the probe issue now..i cant just put cables into the water..even if it doessnt conduct highly..any ideas pls...maybe combination of some parts

That is the advantage to either reed or hall effect sensor, you can include them in a sealed tube with no water contact.
Max.

 

You could go to a simple switch mechanism as shown below.
The float, maybe a bottle with some water in it to weigh it down a bit, and the weight need to be heavy enough to operate the switch.
The float cord passes through a ring on the end of the switch arm and the clamps on the cord set the on and off levels.
I have seen this in use before. The hardest part is making an arm to suit an available switch.
Also ensure end stops are there to prevent the switch getting damaged if someone pulls on the cord.
An added benefit of this is you can see the tank level by the position of the weight.