About 20 years ago, a friend of mine came to me saying that he had to repair a customer’s  water level control made out of electromechanical relays which was falling apart.  He understood that the original control relied on conductivity of water. The customer didn’t want any type of float switch so he had to stick to the way it was meant to work.

He could start the pump whenever water fell below the “low” level electrode and pump would stop once it reached the “high” level electrode but, as water was consumed and its level barely dropped just below “high”, his circuit would re-start the pump just to stop it as soon as “high” electrode was touched by water again. This process kept going on and on until he switched power off. His circuit was oscillating which was not good for a 5 HP water pump or any pump at all.

He needed help. At this point I asked him that instead of working with relays, wouldn’t it be nice if the control were electronic which would probably be less expensive, more reliable and have a longer life?

 I intended to build a kit for Club Jameco out of how I remembered this control worked and this is what this instructable is all about. 

*** Disclaimer: This kit is meant to operate with equipment such as line operated water pumps or motor starter relays and/or contactors at lower control voltages. Line voltage is dangerous and if mishandled can cause injury or death. If you are not familiar or have not worked with line operated equipment, have a licensed electrician do the power wiring for you. This kit is meant to be educational in nature and can be used with line operated equipment if National Electric Code guidelines are followed. ***

Step 1: Proposed Control Slide show

The slide show included in this instructable shows the basic operating theory behind this control. It assumes that the pump is a small plug-in pump. This control has a small 12V coil relay whose contacts are rated at 10A 120V. You can select any relay to suit your water pump's power source.

hi, thx for the great toturial. I've redesigned the circuit and make it more compact. just removed the voltage regulation part and re order other parts. it's working now in my aquarium with titanium sensors. thx again.
<p>Hi rlarios, i want to say thank you for sharing this wander full instructable and I have a question, hope you can answer.</p><p>Can this circuit work in 5v? I have tons of 5v phone chargers, would be perfect for me :)</p>
Hi Mark 62726,<br><br>Thank you for your comments.<br><br>You can have the CD4001 operate off 5V. You would need a 5V coil relay with contacts rated at least at 1A at 120Vac, and instead of the rectifier diodes and 7812 voltage regulator, you could use your 5V phone charger.<br><br>rlarios<br>
<p>I want to make a printed PCB. So what can I do. I checked your cadsoft eagle file but it is doesn't seem to work on my cadsoft eagle so what can I do. Pls send me PCB design in PDF format so I can print it and itche it on PCB.</p>
<p>Hey, I made the water level controller , it worked alright when i tested it in buckets, but after installing it in underground and overhead tanks, it dosent seem to work , it simply keeps the pump switched on although all the levels are submerged.</p><p>what possibly could be the problems ?</p><p>Please help me with it . </p><p>I can provide images if you need them.</p>
Hi there DarshP5,<br><br>Please provide pictures showing all electrodes in overhead tank which is the one that controls pump operation. <br><br>rlarios<br><br>
<p>First I tried using a aluminium strip , but the circuit dint work , so i used a metal Screw as i had tested with metal screws in the bucket, i have posted the pictures of them all , the black and blue wires are the ground , green is the lower level and the red one is the upper level , and the blue one is the pump protect. (dont worry the pump protect and the ground wires are submerged in the underground tank.) and the other wires are as shown in the picture. Any Help Would Be Appreciated . :) thanks<br></p>
<p>DarshP5,</p><p>Wires wrapped around screws the way it's shown in pictures won't work properly. Crimp round terminals to wires ends and fasten terminals to either stainless steel or galvanized bolts using nuts and washers for a secured connection so they can be used as electrodes. </p><p>I believe you can find these bolts, nuts and washers at home depot or your local hardware store.</p><p>Let me know how this works. If you're still stuck with it at least we know electrodes won't be a problem. </p><p>rlarios</p>
<p>hey , sorry for the late reply.</p><p>i found out the problem , it was a small cut in the ground trace of the PCB , i fixed it, but now the circuit is acting weird , as it turns on the pump as soon as the water goes below the upper level. and then, the pump protect seems not to work and infact the circuit only works only when they are out of water. Its confusing ! please help :)</p>
DarshP5,<br><br>Show me a picture of solder side of your PCB.<br><br>rlarios<br>
<p>Sure, here it is </p>
First clean flux residue with a cotton swab soaked in alcohol. Make sure board is clean on component side as well.<br><br>Let me know if it still doesn't work so we continue debugging your control board.<br><br>rlarios
<p>Is this circuit is operate on AC current?</p>
<p>it depends on what you mean by that. Circuit operates on dc and I've seen some varying low voltage can be used and then rectified in order to be detected. </p><p>There are other circuits out there that operate off ac power using relays, in case you're interested look them up on YouTube. </p><p>rlarios</p>
<p>What to do to circuit to operate it on DC....</p>
<p>See comments below. </p>
<p>please can you send me the grafcet explain the operation of this project ???</p>
<p>please can you send me the grafcet explain the operation of this project ???</p>
<p>I put the cd 4001 in with pin 1 towards r1. Is that correct?</p><p>Better pictures would be nice for those of us who are color blind and too old to read tiny things.</p><p>Big question is can I substitute float switches for the top and bottom sensors to ground?</p><p>I could guess the 12 v dc needs to be on until the water lowers and breaks the circuit for the bottom sensor, and rises and finally breaks the circuit for the top one.</p><p>or vice a versa - My floats can go either way.</p><p>Going to use this to run a vegetable hydroponic garden on the balcony of my appt. About half of the time their roots will be submerged. </p><p>Have heard that plants are highly reactive (grow faster) to voltages - would like to run two test - one with the roots being grounded and the top of the plant with a weak dc positive charge, and another with the inverse. (will be an interesting test)</p><p>can I do that with this circuit? At least one of them?</p>
<p>Dear MikeL50,</p><p>Please review attached image. This DIP (Dual In-line Package) has an index mark on one end. Hold the IC so this mark is at your left, then the first pin below this mark is pin 1. Hand sketched drawing will show the pinout of this IC seen from the top.</p><p>Float switches (N.C.: Normally Closed) can be wired as shown in same picture as well. By the way, the attached picture was changed as previous one was not drawn correctly. </p><p>Hope this helps, let me know if you need anything else.</p><p>Regards</p><p>rlarios</p>
<p>MikeL50,</p><p>By the way, I forgot to confirm that CD4001 pin 1 goes to one end of R1 just as you said. The other end of R1 goes to +12V.</p><p>rlarios</p>
<p>Saq,</p><p>Replied though email and not sure if it will show up here in the forum or not. Try clicking the download pdf link, if not, go to the Jameco kit link below. Theory and schematic are in their docs I believe. Good stuff there. </p><p>Kid</p>
<p>can u mail me circuit diagram of this project.</p><p>shaikhsaqlain10@gmail.com</p>
<p>I built a radon mitigation system for my well water. This controller worked great!</p>
<p>hi, its a cool project, is there any way that i could get the pcb design?</p>
<p>Nice one! I have built a similar one on a bread board and tested by keeping it running for about an hour. Ionization leads to deposits on the leads/terminals inserted in water. Won't this affect performance over time and hence, required cleaning of such inserted leads periodically? If yes, is there any way to avoid this?</p>
Hi rlarious I'm back ;)<br>I was just thinking can we replace the transformer from that circuit<br>i.e, can we directly use the 12v dc adapter supply for the circuit<br><br>Can u plz tell me which components should be removed for that or how will the circuit be look like after doing that<br><br>I think those 4 diodes, 7812 voltage regulator should be removed but what about the capacitor<br>Plz help me out soon
<p>Remove capacitor as well. If wires from DC supply are longer than 3 inches, install a 0.1uF cap.</p><p>One more thing, make sure your DC PS is isolated from the mains by means of a transformer.</p><p>Good luck.</p>
Could you plz upload an image of the new schematic for the dc adapter, as I'm having some trouble with it right now<br>Thanks once again.
<p>The DC adapter you intend to use should have an isolation transformer inside. This means, there must not be any electrical connection between mains and the adapter's output such as is the case when these adapter's rely on auto transformers. The +12V DC and ground wires from your adapter would go to the +12V rail and ground line of the circuit, respectively. Forget about the 0.1uF capacitor. This is simple, just two wires from your adapter to the control.</p><p>rlarios</p>
One more thing shall i remove all the capacitors , 4 diodes, and 7812 regulator
<p>Remove D1, D2, D3, D4, C1, C2, and 7812 voltage regulator. Leave C3 installed.</p>
this design for water level control is the best i have seen in terms of simplicity of design and dedication to control limits. How can i get about 25 pcs of the pcb used in the design?, as other components is already available here.
Stevobaba411,<br><br>Unfortunately, the only source for ready built kits is jameco:<br><br>http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2169109_-1<br><br>Thanks for your comments.<br><br>rlarios<br>
Thanks a lot rlarious for such a great project<br>But i am facing some problem<br>Whenever i start the circuit<br>With or without the ic<br>The relay stays on no matter which condition it satisfies<br>So i thought to try the solution you told to vickys11<br>After doing that<br>The voltage supply for in condition i.e, when wires are dipped in water are perfectly the same reading but the voltage reading for the out condition<br>When wires are not in the water<br>The reading comes out to be 3.6 v instead of 8 to 9 v<br><br>Plz help me out soon as i need to submit my project<br><br>And yes the last question asked my vickys11 does make sense to me<br>As it will make the circuit smaller and less complex <br>Thanks a lot again.....
<p>Make sure pull up resistors are 2.2 M-Ohm. </p><p>Check your circuit very well. Also, make sure you are using a CD4001 IC. The readings you should get are consistent when tested with tap water or well water. If you're using distilled water, it won't work. Remember, 2.2 M-Ohm resistors form a voltage divider with water.</p><p>Good luck.</p>
Thanks rlarious<br>That was my mistake which i figured it out<br>Thanks to u<br><br>The circuit is working just fine but the red led is set to be turned on 24/7 no change is taking place when the inputs are been changed.
<p>Are you using same transistors and resistor values? The only function of those transistors is to turn red LED on and off depending on water level at pump protect electrode.</p>
Thanks a lot rlarios !!!!!<br>I know replying after a long time. ;)<br>Its finally working now<br><br>I just had a one more doubt<br>I made this circuit on pcb board home made using etching process<br>My ques was that<br>Can i use this circuit for a long period of time lets say 5-6 years<br>And can i turn on the circuit for 24/7<br>Can that create a problem using it for 24/7<br>Hope you will help me out soon<br>Thanks ;)
Remember the story I started this instructable with? Well, my friend and I installed the perf board circuit next to the motor starter without any enclosure, just hanging off a wire tied around a screw making sure no exposed energized parts would touch anything. <br><br>My friend said after a couple of tests: &quot;I'll come back next week to put this board into a proper enclosure.&quot; To me, this was just an experiment and Ii didn't have the intention to get any money in exchange. I forgot about the whole thing for about 4 or 5 years.<br><br>One day I got a service call from a customer close to where that water level control was installed. After taking care of business, I was intrigued as to what had been the fate of that control. Off I went to find out.<br><br>The place where this was installed was a small clinic. I got into the mechanical room and nobody was there. I went to the area where the perf board had been installed and guess what? The control was still there hanging off the same wire tied to the same screw! My friend never came back to put it into an enclosure!<br><br>A maintenance guy approached to me and told me I shouldn't be there and asked what I wanted. After telling the whole story, he said they didn't know where that controller had come from. All he knew was that they had to keep it clean and make sure it never failed. This water level control was meant to make sure they always had &quot;clean&quot; water available for doctors during surgery. Scary, isn't it?<br><br>I left the place with a feeling that something I built actually worked. And, yes, it was on 24/7.<br><br>rlarios<br><br>
Thanks for such an gr8 circuit but<br>I'm facing some problem with the circuit<br>The low level of the upper water tank is not working<br>i.e, motor just get started as soon as a little amount of water is taken out out of the upper water tank<br>Hope you will help me out soon<br>Thanks ;)
<p>Hey VickyS11,</p><p>That's a nice circuit board you got there! Now, you will have to test the circuit the way it was tested in the last steps of this instructable.</p><p>Get yourself a multimeter in DC Volts, and test the low level electrode input on pin 1 of CD4001, when low level wire is into and out of the water in the cointainer you'll be using for testing. When wire is out of water, voltage should be around 8 to 9 volts, assuming your PS is 12V. When wire is into the water, voltage should be around 0.8V. Remember, Ground wire must be into the same water container all the time, otherwise, you won't get these readings!!!</p><p>If you want Green LED to come on, pump protect and ground wires should be dipped into the same water container. If the voltage readings you got in previous paragraph were about right, dip Low level wire along with Pump Protect and ground wires in same water container. Green LED should stay on as this simulates water level going up. As soon as you dip High level wire into same water container, Green LED will go out which simulates pump being turned off.</p><p>To simulate water level going down due to consumption, pull High level wire out of water container and Green LED should remain off. As soon as you pull Low level wire out of water container, Green LED will come back on again.</p><p>If for any reason, your circuit does not behave this way, make sure to also test CD4001 pin 13 which corresponds to S-R latch input that comes from High level wire through a NOR gate wired as a NOT gate. Remember that High level wire goes first to CD4001 pins 8 and 9 which are the inputs of gate wired as NOT gate, pin 10 is its output which is connected to pin 13 of CD4001. So, if High level wire is into water along with ground wire, pins 8 and 9 should read around 0.8V. CD4001 pin 13 should read around 12V. When High level wire is out of the water, pins 8 and 9 should read about 8V to 9V and pin 13 should read between 0V and 0.8V.</p><p>For proper operation of S-R latch, check truth table on slide show in step 1 and verify its outputs as you test inputs. Also, check for proper continuity in all traces on your circuit board. There may be an open line or solder bridging somewhere. </p><p>Hope this helps.</p><p>rlarios</p>
Thanks rlarios for such a detailed info<br>I will definately try this out<br>Btw u wanted to tell u that i have used 15k ohm resistor instead of 2.2m ohm which is close to the relay( and that adjustment worked)<br><br>And now a new problem came out that the high level probe is not able to switch off the motor<br>Previously it was working<br><br>And in first query the problem was<br>Once the tank gets full after that if the high level probe is taken out the motor get started within a sec<br><br>Btw thanks a lot
<p>VickyS11,</p><p>The 2.2M ohm resistors and the &quot;equivalent&quot; resistance of water form a voltage divider between 12V and ground. Your 15K ohm resistor is less than 1% the value of 2.2M ohm, no wonder the circuit is acting up.</p><p>There are three electrode inputs, therefore, there is one 2.2M ohm pull-up resistors at each input. If voltage does not change the way I described in my previous message as you dip and pull wires into and out of water, then change resistors back to 2.2M ohm and test again.</p><p>Even the circuit with transistors -to turn red LED on and off- was designed taking into account this 2.2M resistor because pump protect electrode wire goes into CD4001 pin 6. The purpose of these resistors is to ensure that logic levels will be properly detected by CD4001.</p><p>Let me know how things turn out.</p>
Thanks for such a detail... I have implemented this at my home...Every thing is working fine... However i want to enhace this circuit to avoid base tank over flow such that if base tank reaches high motor should start untill overhead tank reaches high or base tank reaches pump protection
<p>Hi AnsariT,</p><p>In the circuit schematic, you'll see that when water level in upper tank is below LOW level electrode, pump would start provided water level in &quot;base&quot; tank is above PUMP PROTECT electrode.</p><p>You can add a a &quot;base&quot; tank overflow electrode and run a line through a NOT gate. The output of this NOT gate would become one input of a 2 input OR gate, the other input would be the LOW level electrode. The output of this OR gate would take the place of the LOW level electrode into the S-R latch formed by the two NOR gates.</p><p>Try this (at least on paper) and let me know whether this Works for you.</p><p>rlarios</p>
Thanks.... I was hoping existing ic will do this by some how manipulating the input of ic pin... Any will try your suggestion once i get time and update the thread
<p>AnsariT,</p><p>The base tank overflow electrode is an extra input that needs to be processed. The circuit -as is- in the instructable used all 4 gates in CD4001. You can use an extra CD4001 and manipulate the gates to behave the way I described in my previous message. I can send you a schematic later today.</p>
Hey is urs low level wire of the upper water tank is working<br><br>i.e, as rlarios told in the tutorial that if circuit is on it will check that the water gets down below of the low level wire ( once the tank is full ) and then it turns on the motor<br><br>plz help me out<br>Thanks ;)
<p>Hi there!</p><p>I would be interested in adapting this to be used to top up my pool automatically.</p><p>I already have water supply under pressure, so I was just hoping to have this circuit open a valve to add water until the pool is full again. So the stop limit would be just below the skimmer box top and the add limit would be just before the skimmer box has no water.</p><p>I have some electronics knowledge and can solder and follow instructions well enough, but need guidance to what to do and what I need.</p><p>Cheers,</p><p>Josh</p>

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