Super Simple Water Level ControlPART NO. 2169109

Design a simple water controller in which electrodes are required to sense high and low water levels in a tank. Whenever the waterlevel falls below the low level electrode, the water pump starts and it stops once the water level touches the high level electrode.There is a third electrode which is used to detect the water level from the pump suction port tank. If this electrode does not sensewater, then the pump is not allowed to run. This protects it from burning out. Power is obtained from the AC line through an AC-to-ACWall transformer. The control electronics and relay work from a 12VDC voltage regulator. It is assumed that you have a water pumpalready.

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

Time Required: 1 - 2 hours depending on experienceExperience Level: IntermediateRequired tools and parts:Soldering ironSolderWire stripper and cutterNeedle nose pliers1 - 100' roll of 24AWG wire (Jameco P/N: 734411)1 - AC-to-AC wall adapter (Jameco P/N: 101258)1 - Small flat screwdriver

Bill of Materials:

Qty Jameco SKU Component Name1 12562 IC, CD400110 38375 PNP Transistor10 38359 NPN Transistor1 51334 +12V Voltage Regulator10 35991 Rectifier10 253753 Red LED10 253631 Green LED100 691657 2.2 M-Ohm Resistor100 691366 120K Ohm Resistor10 661423 470 Ohm Resistor10 691024 4.7K Ohm Resistor10 198978 330uF 35V Capacitor10 30496 220uF 25V Capacitor10 330431 1uF 25V Capacitor4 2094506 Connector Terminal block 2 Pos 10A1 144186 RELAY,12VDC@15A,SINGLE POLE DOUBLE THROW (SPDT) 10 691147 15K Ohm Resistor10 112214 IC Socket

Step 1 - Schematic diagram

This shows the schematic with circuit component reference numbers

Step 2 - Check parts

Before soldering anything in place, make sure you have all parts required. See parts list. (Extras are OK)

Resistors

3x - 2.2M ohm 1/4W(R1, R2, R3)1x - 4.7K ohm 1/4W(R4)1x - 120K ohm 1/4W(R5)2x - 470 ohm 1/2W(R6, R7)1x - 15K ohm 1/4W(R8)

Capacitors

1x - 330uF 63V(C1)1x - 220uF 25VC2)1x - 1uF 63VC3)

Semiconductors

5x - 1N4004(D1, D2, D3, D4, D5)1x - CD4001 (IC1)1x - 7812T(IC2)1x - Green LED(LED1)1x - Red LED(LED2)2x - 2N3904(Q1, Q3)1x - 2N3906(Q2)

Miscellaneous

1x - 12V coil Relay(RLY1)4x - 2 Terminal connector(X1, X2, X3, X4)1x - Printed Circuit Board1x - 14pin IC Socket

Step 3 - Solder passive components

Assembly instructions.

1) Solder in R1, R2 and R3 which form part of signal input circuits. These resistors are 2.2M ohm. 2) Solder R4 (4.7K ohm resistor) which is a base resistor for transistor Q3 whose task is to switch on-off relay RLY1. 3) Solder in R5 (120K ohm emitter resistor) for Q1.4) R8 (15K ohm resistor) that connects Q1 collector to Q2 base. The purpose of these two transistors is to turn on a red LED to give avisual indication when the water level is low at the pump suction port. Solder in R6 and R7 (470 ohm 1/2W resistors) that are LED1and LED2 current limiters.5) Insert electrolytic capacitors C1 (330uF) and C2 (200uF) in their corresponding holes paying attention to the marked up negativelead of capacitors for polarity before soldering in place. Insert C3 (1uF) decoupling capacitor following the same guidelines as C1 andC2.

Step 4 - Install power supply components and IC socket.

Before installing the diodes, make sure they are properly oriented for polarity. The black band mark on the body of the diode tells youthat lead is the cathode. The printed circuit board should also have a mark indicating the cathode.

Insert D1 rectifier diode in its intended space and solder one lead at a time. Clip on a heat sink between the solder joint and the bodyof rectifier. This heat sink will absorb excess heat and keep the semiconductor relatively cool to avoid prematurely shortening itslifespan. Before soldering the other lead of same semiconductor, wait about 15 to 30 seconds to let the rectifier to cool off beforecontinuing with the other rectifier leads. Always use a clip-on heat sink before soldering any semiconductor lead. Do the same withD2, D3 and D4 rectifiers.

Diode D5's function is not meant to operate as a power supply rectifier but is the same device as the previously soldered rectifiers.Solder diode into D5 location paying attention to where the cathode goes. The function of D5 is to protect transistor Q3 from therelay's coil kick back voltage when it is de-energized.

Put 7812T in place and before soldering its first lead, use the same clip-on heat sink between the soldering joint and the body of theregulator. After soldering first lead, wait a few seconds to let the device cool off. Touch the 7812T regulator to make sure it's not toohot before proceeding with next terminal and so on until you're finished with the third and last terminal of the regulator.

Install the 14-pin IC socket and solder it in place. Use just enough solder for each pin to keep adjacent pins from shorting togetherwith excess solder. Note the position of the notch on one side.

Step 5 - Verify power supply operation

Using an external +15V DC Power Supply (or two +9V batteries in series) and a couple of alligator clips, connect the (+) output of thispower supply to the anode of D1 and the GND output of the power supply to the cathode of D4. Measure voltage between pins 7(gnd) and 14 (Vdd) of the IC socket which should be +12V +/- 2%.

If this voltage test proves successful, proceed to next step.

Step 6 - Install transistors and LEDs

Install 2N3904 NPN transistors into Q1 and Q3 positions making sure all terminals go into their corresponding holes. Attach theclip-on heat sink before soldering each lead with the right amount of solder and wait at least 20 to 30 seconds before moving to nextlead of same device. Do the same with 2N3906 PNP transistor on Q2 position.

Install the green LED into the LED1 position. The shorter lead is the cathode and should go where the cathode lead is marked on thePCB. If LEDs are reversed they won't turn on. Attach clip-on heat sink to the lead you will solder first, wait 20 to 30 seconds beforesoldering the anode. Do the same with the red LED into the LED2 position.

Step 7 - Finish assembly

These connectors come with two terminals each. Install one connector each into X1 and X4 positions and solder in place with theterminals facing to the edge of the PCB. These connectors come with a sliding lip on one side and a groove on the other. Take theremaining two connectors and put them together by sliding one connector's lip into the other connector's groove so they stay attachedand insert them into X2 and X3 positions and solder in place with terminals also facing to the edge of the PCB.

Install the relay into RLY1 position and solder it in place. This completes the assembly of this kit.

Step 8 - Final testing

Place your assembled kit on an insulated surface such as a file folder or notebook on your workbench to avoid shorting the solderjoints with conductive material that may be sitting on your work surface. Get a couple of one foot 24AWG segments of wire and stripthe ends. Insert one wire's end into the terminal marked as "Ground", then insert the another wire into the terminal marked as "Pumplevel protection" leaving the other ends loose without touching one another.

This is a test with the same DC power supply used in step 4. Connect it the same way to power up the circuit. At this point, theCD4001 should already be inserted into its socket. Once power is applied to the board and assuming everything was properlyassembled, the red LED should turn on. At this point, if you put together the two stripped ends of the wires previously attached, thered LED should go out and the green LED should turn on and one click should be heard coming from the relay. Separating the wires'ends should turn the green LED off and the red LED on while hearing another click from the relay as it de-energizes. This proves thecircuit is working.

Get yourself a small shallow container and fill it up with water. With the circuit still energized, the red LED on and the two wires nottouching to each other, dip both stripped ends into the container with water. The red LED should turn off and the green LED shouldturn on with one click heard from the relay. Remove the wires from the water and the green LED should go out, the red LED shouldturn on with a click heard from the relay. If this goes as outlined, then it is working properly.

AC-to-AC wall adapter test:

Now it's time to test that the kit will work with 12VAC coming from an AC-to-AC wall adapter such as Jameco P/N: 2076543. Ourpump controller kit does not include a male connector adapter, so cut off the female plug from the wall adapter cord and strip the endswhich should be the 12VAC adapter output. Connect these 12VAC leads into the connector marked as 12VAC IN. Plug the walltransformer into a wall outlet and the board should perform the same as with the DC power supply. If this is the case, then it's time fornext test.

Water Pump test simulation:

Get another pair of wires of about the same length as the wires already connected to your kit, strip their ends and insert one in the"Low level" terminal and the other in the "High level" terminal. With the pump protection and ground wires already dipped into thewater container, the green LED should be on. Dip the "low level" wire end into same water and the green LED should still be on, thendip the "High level" wire also into same water container and the green LED should go out with a click heard from the relay. Thissimulates that the pump filled up the water tank. To simulating water consumption as water level goes down, remove the "High level"wire from the water container and nothing should happen. Then, remove the "low level" wire from the water container and the greenLED should turn on and the relay should energize the water pump and the cycle will repeat.

Step 9 - Final installation

You will need now an external 12VAC wall transformer such as Jameco P/N:2076543 to energize the kit. You will also need a properenclosure which can be found in a Jameco catalog. You will have to run wires between the kit and the water tank and pump waterreservoir as shown in the schematic. This schematic shows there are thin metal rods inserted through the walls of the tanks for sakeof simplicity. You can somehow accommodate the rods vertically from the top of the tank making sure that these rods don't touch oneanother. If you prefer to drill through the tanks' walls, make sure that the rods or bolts used are properly sealed to avoid leaks due topressure from water on the walls of the tank.

Once you do the connections, the controller should work without problems showing when the pump is running or when the pump isprotected due to a low level at the pump suction intake.