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Build Your Own Water Level and TDS Sensor

One of the challenges in drilling wells is finding the depth of the water, the water recovery rate

and the quality of the water. Normally, two measuring devices are used. One, an Electric WaterLevel Tape, and the other, a TDS or Total Dissolved Solids Meter are used. Both are very

expensive instruments which use fragile electric meter movements to detect electric current. Thechallenge facing those drilling wells in third world countries is to have something that does the

same thing in an inexpensive rugged instrument.

One option is to build an astable multivibrator using a TLC555 timer. This timer is ideal becauseof its extremely low power consumption. The circuit can be built right into an older style

telephone handset with all components (probe excepted) included in the handset . The circuitworks by sensing the resistance of the probe. If the probe is open (not touching water) the circuit

will produce an audio frequency around 400 hz. When the probe touches quality water, the

frequency doubles (approximately) increasing the tone by about one octave. If the water hasdissolved solids in solution, the tone will quickly go higher giving the person measuring anapproximation of the mineral quality of the water. A fairly high note, nearing a squeal would

indicate the detection of brine or extremely high levels of hardness etc. If, for some reason theprobe shorts, the circuit will produce a very high pitched whistle that will not change when the

probe comes in contact with water. Though this circuit does give a approximate estimate of thehardness of water, it will not give a good estimate of the SAFETY of the water. For a further

explanation of its limitations, please go to Frequently Asked Questions

(If you go to a picture, or diagram via a link or camera, just hit your Back Button to return to theplace you came from.)

The circuit once attached will fit nicely under the speaker with the speaker unit in place. Aminiature momentary push button switch should be used between the 9V Alkaline battery and

the circuit . This ensures that the unit cannot accidentally be left in the on position. The

switch is best mounted near the ear speaker where it can be easily depressed by the thumb orindex finger. The battery can then be installed where the microphone and microphone socket

were installed.

The probe wires can exit out of the original curly cord inlet. Once the wires are installed, this

hole should be sealed with silicone (Do NOT use Mono as a sealant since it has electricalproperties that enable the flow of current which messes up the reliability of the circuit.) The

probe wire can be from 50' - 500'. In our first model, we used standard 24 gauge speaker wirebecause of its flexibility, size and price. 100' of probe speaker wire can nicely be wrapped

around a piece of wood siliconed to the back of the handset for easy storage and portability

. A round non porous rock, approximately 1" in diameter works well as a weight for the probe

. Using a little silicone and an elastic band will attach the wire to the rock. Make sure that you

do not cover the tinned wire ends with silicone.

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Parts List

Quantity Description

1 Northern Electric Style G3 Telephone Handset with ear and mouth covers

1HHMR-80V(U-1) Receiver Unit, Diode must be Removed (clip it off ifnecessary)

Other possible part numbers (1182, ?)

2

1/4" Long Connecting Screws for the above Receiver. These will be used to mountand connect the circuit board to the receiver unit. If you have an older reciever unit,

1/4" screws will already be on the reciever. If however you have a newer unit, 1/4"screws will have to be obtained since the included 1/8" screws are not long enough.

4#12 lock washers to improve the connection between the receiver and prevent shortson the foil side of the circuit board.

1

Momentary On Push Button Switch (i.e.. push to talk switch, the smaller the

better) The quality of this switch is essential since it is the one moving part in theentire unit.

1100' (or more) 24 gauge multi-stranded or braided speaker wire (flexibility, size and

durability are essential considerations)

1

Water Sensor Printed Circuit Board (make it if you have the resources, skills and

equipment, or order it directly from us. Mask information is included below if youchoose to make your own circuit board)

1 TLC 555 Timer

1 10K Ohm Resistor (brown-black-orange) 1/4 or 1/8th watt

1 1K Ohm Resistor (brown-black-red) 1/4 watt

1 2.2K Ohm Resistor (red-red-red) 1/4 or 1/8th watt

2 .1uF capacitor

1 1 foot black stranded internal connecting wire

1 1 foot red stranded internal connecting wire

1 9V Battery Connector

1 9V Alkaline Battery

Tub and Tile Silicone Sealant

1Wooden Wire holder shaped as pictured below made to fit the back side of thetelephone hand set.

3 General Purpose Elastic Bands

1 Round Rock 1"

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Step by Step Building Instructions

1. Printed Circuit Board Preparations

A. Obtain the "Well Sensor Printed Circuit Board" and proceed to install the parts as shown inthe graphic immediately below. This view has the copper foil on the bottom side. All partsshould be installed right on the circuit board without extra lead length. This encourages

ruggedness.

1. Install the 1K Ohm Resistor (black-brown-red) tight against the circuit board in positionR1.

2. Install the 2.2K Ohm Resistor (red-red-red) tight against the circuit board in position R2.3. Install the 10K Ohm Resister (black-brown-orange) tight against the circuit board in

position R3.4. Install the TLC555 timer snugly on the top of the circuit board. Make sure that Pin #1 is

situated as marked below! Pin #1 is usually marked by a dimple on the printed circuit that

cannot be worn off (like print). Make sure that all 8 pins are protruding through thecircuit board! Bend two pins at opposite corners of the TLC555 to hold it in position

until you solder it.5. Install an insulated jumper wire as shown.6. Install two .1uF Capacitor at C1 and CAdj

B. Turn the printed circuit board over, carefully place it in a small vice to keep it secure andsolder the components onto the board. Because of the size of this circuit, it is recommended that

a person with electronics experience do this task. Overheating can damage the circuit board or its

components. Under heating can cause the solder to bead and make a poor connection. Qualitysoldering equipment makes a world of difference! A site that shows and teaches you how to

solder ishttp://www.epemag.wimborne.co.uk/solderpix.htmOnce the parts have been properlysoldered in position, clip off any excess lead length, as close to the circuit board as possible

without clipping the actual soldering itself. Clipping the soldering can break the solder bondbetween the lead and the foil. Leaving the leads too long will cause the unit to short once it is

mounted on the back of the receiver.

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R1 = 1000 Ohms C1 = .1uFR2 = 2200 Ohms C2 = ~.1uF

R3 = 10K Ohms

Your Circuit board should look like this once the parts have been soldered in place.

2. Handset Preparations

1. Remove microphone, microphone socket, curly cord and wires from the G3 TelephoneHandset. Retain the receiver (speaker) as it will be used in the set. If you have notalready done so, REMOVE THE DIODE FROM THE BACK TERMINALS OF THE

RECEIVER (SPEAKER).

2. Drill a 5/16" hole in the neck of the handset near the ear piece as shown below.

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3. Take the Miniature Momentary On Push Button Switch and connect a 3" stranded REDwire to one terminal and a 9" stranded RED wire to the other terminal. Make sure that

these connections are properly soldered.4. Place the 3" wire through the Vdd terminal on the circuit board from the top side. Solder

the wire in place.

5. Connect a 12" BLACK stranded wire to the GROUND terminal of the Well SensorCircuit Board, soldering it in place.6. Take the Telephone handset and insert the probe wire into the original curly cord hole

near the mouth piece. Slide the wire through the handset to the Receivercompartment. Run a little extra through so that you will be able to attach it to the circuit

board with ease.7. Strip 1/4" off of the end of each of the probe wires, twist and tin them. Insert them in the

above probe connection locations, solder in place, clip off ANY excess wire on the foilside of the circuit board.

3. Attach the circuit board to the receiver.1. Insert the two #12 X 1/4" screws through the circuit board from the component side.

(They should fit through the holes snugly).

2. On the foil side of the circuit board, with the screws protruding, place 2 lock washers oneach screw. These lock washers will ensure a connection to the receiver and offset the

circuit board so that the soldered copper foils will not short on the back side or metalportions of the receiver.

3. Mount the circuit board on the receiver. . Tighten the screws so that they are just snugand the lock washers have been compressed. This will ensure a continuous and secureconnection.

4. Putting the Handset Together

1. Mount the Push Button Switch in the 5/16" hole making sure that the RED 9" strandedwire proceeds through the handset to the battery compartment (mouth area) of the unit.

2. String the BLACK 12" stranded wire through the handset so that it also protrudes fromthe battery compartment.

3. Attach the 9 Volt Battery connector - Red wire to red wire, Black wire to blackwire. Solder the connections and cover them with a dollop of silicone. Let the silicone

dry.4. Attach the battery taking note to make sure you are attaching it with correct

polarity. This circuit is not protected against those who try to put on batteries backwardswhile pushing the power button!

5. Once the battery is installed, push the power button. You should hear a frequency thatwould compare to a middle "C" on a piano. If you hear this sound - Congratulations -

you have passed test #1.6. Double check your connections.7. Carefully insert the 9 Volt battery in the mouth side of the Telephone handset aiming the

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end of the battery down the throat of the handset. It should "just fit!" If it is a littletight, you might choose to scrape a little out of the opening edges of the throat of the

handset with a sharpe knife. DO NOT CUT THE WIRES BY ACCIDENT! Newerhandsets should easily have enough room. Once the battery is in place, screw on the

microphone/battery cover.

8. Carefully guide any excess wire into the ear section of the Telephone handset as youinsert the Receiver with the circuit board mounted on its back side. The receiver shouldfit flush with the edge of the handset opening. If you find it does not want to fit, take it

out again. You may be pinching a wire if you force it into place. If it fits properly, placethe ear cover over the receiver. Once again, push the power button, you should hear the

same frequency. If you hear the same sound - Congratulations - you have passed

test #2.

5. Preparing the probe.

1.

At the end of your probe wire (100' or more), strip off 1/2" and tin the wires withsolder. This will give the copper some protection from corrosion (salt water corrodesalmost everything).

2. Take a permanent marker (Sharpie Permanent Markers work very well for this.) Startingfrom the tinned end of the probe, mark with a black marker at 1' increments the entire

length of wire. Once this is done, go back to the tinned end, and then with a red maker,add a blue line at every ten foot increment, with an extra line or each additional 10'

increment. In between, at 5', 15', 25' 35' 45' 55' etc... place a line with red marker toindicate the 5s on the wire. This will help to measure the depth of the sensed water.

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The probe can be weighted with a 1 inch marble or even a simple non porous rock, tied between

the leads with an elastic band or siliconed between the leads. If you happen to loose the rock,

replacements should not be hard to come by!

6. Preparing the Probe Storage Block

Put your well water sensor to the side. Find a piece of wood approximately 1" wide. If you uselighter wood, it is easier to cut and shipping costs less! Cut it to the shape shown below. You

may want to use the template provided below. Print it out, it should print out to the rightdimensions. Once you have cut it out, sanded and or finished it to your pleasure, silicon it to the

back of the handset. Let the silicone cure. Once the storage block is secure, carefully wrap thewell water probe wire around it. Want to Print out the block we made to scale -Click here to

Go to WoodBlock Diagram

7. Test your Well Water Sensor

1. Pressing the power button should produce approximately a "middle C."2.

While pressing the power button, dip the probe in pure water, the tone should go up about1 octave.

3. Start adding a little salt to your sample of water and stir the water slightly. Notice howquickly the unit detects salt in solution.

8. Calibrate Your ProbeThe advantage of using musical tones for the purpose sensing water and water quality is that

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musical tones are understood throughout the world. This Well Water and TDS sensor can berelatively calibrated very simply. The procedure for calibration is follows:

1. Find a pure sample of water. This need not be distilled H2O, it should be, however waterthat would be regarded as high quality by Hydrology standards.

2. Make sure you have your rock or other non - metallic weight permanently attached toyour probe wires.3. Depress the activator button and slowly dip your probe into quality water. The tone

should progressively go up about 1 octave. If it does not quite go up an octave, you

either are using extremely low TDS water, or your exposed probe length is not longenough. Feel free to strip a little more insulation off of the probe wires and re-tin the

exposed strands. Go back to step #2.4. If you the tone goes up more than an octave, you can trim the length of the exposed probe

lead with a scissors in small increments. Repeat this procedure until you have achieved atonal change of one octave.

5. Now for the sake of coming to know how to measure TDS, add a measured amount ofsalt to the water, record the number of notes, in excess of 1 octave that the toneincreases.

The Well Water Sensor Circuit Board

This circuit board is designed to be mounted directly to the back of a standard telephone speaker

(with the original diode removed). The exact distance from center to center of the mountingholes should be 15/16". Accurately scaled 1-1 and 2-1 positive and negative foil photo masks

are linked below. When mounted on the back of the speaker, the foil side of the circuit boardshould be toward the speaker for purposes of contact with the speaker contacts. Lock washers

should be between the circuit board and the speaker contact to provide spacing and better

contact.

Foil Side of Circuit Board Drawn to Scale

Under this color diagram are links to accurately scaled 1-1 and 2-1 positive andnegative foil photo masks that should print out in exact dimensions.

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Photo Etch Positive tape on 1-1Photo Etch Positive 2-1 (for those with the equipment)

Photo Etch Negative tape on 1-1

Photo Etch Negative 2-1 (for those with not quite as much equipment)

Some Pictures of the actual Well Water Level Sensor

This is the view of the constructed Well Water

Level Sensor. The Rock would normally beattached with an elastic band and some silicone.

The 1 inch thick wooden block on the back ofthe handset nicely holds about 100 Feet of #24

guage speaker wire. If you silicone it to theback of the handle, the connection should be

quite durable.

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An exploded view of the Well Water LevelSensor from the side.

This exploded view shows the momentarypush button switch location. Here the circuit

board has been removed from the receiver.(Back).

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A view of the circuit board attached to thereceiver.(Back)

A view of the foil side of the circuit board and

the receiver. Notice that the diode has beenremoved from the back side of the

receiver. The 1/4 inch screws should fitsnuggly through the circuit board. Notice the

two lock washers on one of the screws in thispicture. These lock washers should be placed

on both screws before mounting on the back ofthe receiver.

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The circuit board mounted on the back of thereceiver. Notice that the capacitors or positionedto take a minimum of vertical height as there is

little room in the receiver compartment once theunit is put together. Look closely and you will

see the two lock washers separating the circuitboard from the receiver.(Back)

The battery fits nicely in the throat of the hand

unit.

Circuit Diagram and Technical Details

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"The TLC555 is a monolithic timing circuit fabricated using the Lin-CMOS* process. Due to itshigh impedance inputs (typically 10

12Ohms), it is capable of producing accurate time delays and

oscillations while using less expensive, smaller timing capacitors then the NE555. Like theNE555, the TLC555 achieves both mono stable (using one resistor and one capacitor and astable

(using two resistors and one capacitor) operation. In addition, 50% duty cycle astable operationis possible using only a single resistor and one capacitor. It operates at frequencies up to 2 Mhz

and is fully compatible with CMOS, TTL, and MOS logic. It also provides very low powerconsumption (typically 1 mW at VDD = 5V) over a wide range of supply voltages ranging from 2

volts to 18 volts.

Like the NE555, the threshold and trigger levels are normally two thirds and one third

respectively of VDD. These levels can be altered by use of the control voltage terminal. Whenthe trigger input falls below trigger level, the flip-flop is set and the output goes high. If the

trigger input is above the trigger level and the threshold input is above the threshold level, theflip-flop is reset and the output is low. The reset input can override all other inputs and can be

used to initiate a new timing cycle. When the reset input goes low, the flip-flop is reset and theoutput goes low. Whenever the output is low, a low impedance path is provided between the

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discharge terminal and ground.

While the complementary CMOS output is capable of sinking over 100mA and sourcing over 10

mA, the TLC555 exhibits greatly reduced supply current spikes during output transitions. Thisminimizes the need for the large decoupling capacitors required by the NE555."

(Quoted from the TLC555 Technical Data supplied by Radio Shack, Catalog #276-1718)

Template for wooden block

Frequently Asked Questions:

Have Questions About this Unit -Email Me, I'll try answer them.

1. Does this sensor detect the quality of water so that I can tell it is Safe to Drink?

Response: The sensor's qualitative measure of Total Dissolved Solids (TDS) is a side bonusthat has nothing to do with the safety of the water. TDS measures the presence of minerals suchas calcium & magnesium (which determine the hardness of water), sulphate, chloride and

alkalinity. Lifewater teaches and practices the use of pathoscreen (bacteria) and nitrate tests toroutinely determine whether or not water is safe to drink. The qualitative TDS capability of the

electric water level tape will be usefull when drilling near the ocean since it will give a roughindication whether or not high salt may be present in the water. This will help drillers decide

whether to spend extra money and complete the well, or whether a certain water bearing veinneeds to be blocked off etc. The presence of sodium chloride (salt) does not make the water

unsafe to drink, but can give it an unpleasant taste and cause premature corrosion of certainpump parts.

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