Irrigacion.Controlada

7/31/2019 Irrigacion.Controlada

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At the time, it was to keep out my roommates' English bulldog. Now it merely separates ~924 square feet from the rest of the

yard.

The ground is tilled and bricks are laid for the center walking path with two 4x4s for the narrower side paths.


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from within my house influence the design heavily. I also wanted this project to be modular, so if I wanted to change the

sensors and power other devices, all I have to do is unplug the irrigation system, plug in something else, and alter the

program.

The design I ended up with is comprised of three 2-lead barrel plugs and a single 3-lead audio plug (float sensor, pump

pressure switch sensor, temperature sensor, and one free port for a future rain sensor), two solid state relay-controlled

electrical outlets (pump and 24v valve), and a blue LED next to each outlet for a visual signal when an outlet is live.


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This is the 1/2 HP well pump I'll be using to transport my water from the tanks to my sprinkler head(s). The rated output is

9 GPM (gallons per minute) @ 30 or 55 PSI (pounds per square inch), and has a current rating of 8.5 amps. At 120 volts,

that's 1020 watts of power consumption. These figures are from the manufacturer. I'll be doing my own testing down the road

to find the actual performance. If we assume these figures are accurate, we can take Atlanta's January, 2012 electricity cost

of $0.113/kWh (killowatt-hour) and project how much it would cost to water every day of an 8-month growing season, for 30

seconds.

(30 seconds/day) x (30 days/month) x (8 months/year) x (1 minute/60 seconds) x (1 hour/60 minutes) = 2 hours.(2 hours run time) x (1020 Watts) = 2040 Watt-hours = 2.04 kWh.

(2.04 kWh) x ($0.113/kWh) = $0.23052 or less than one quarter dollar

Pretty good!


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This is the working prototype, incorporating theArduino Uno, with an ATMega328. The components include a 7-segment

display (top left), a float switch (top center), a real time clock module (top right), and affixed to the breadboard is a

temperature sensor (10k thermistor), two blue LEDs, a push-button rotary encoder, and a couple resistors here and there to

prevent damage to the arduino.

The basic operation will turn the pump on at scheduled times of certain days for chosen durations. If the rain barrels begin

to run low on water, the float sensor will signal the electronic valve to open at the house's spigot. This valve is connected to

one of the two barrels by a hose. This prevents the water level from falling below the pump's intake pipe. A temperature

sensor prevents the pump and valve from powering if it's too cold (or will soon be too cold). A rain sensor will be incorporatedin the near future to prevent watering while or directly after it's rained.
http://www.sparkfun.com/products/9117http://www.sparkfun.com/products/99http://www.sparkfun.com/products/9767http://www.arduino.cc/


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Further progress shows the rotary encoder soldered to its board and the rest of the components plugged in to test before

everything is soldered and tucked in. Surprisingly, the first test has all components properly connected and operating


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flawlessly.


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When powered, this jet pump relies on a pressure switch to enable and disable the current to the motor. In a situation

where there is a blockage in the outflow line (debris collecting in the sprinkler filter, for instance), pressure can build up. If the

psi that's measured in the head exceeds ~50 psi, the switch will kill the power to the pump. If no pressure tank is installed,

the line pressure quickly drops and the switch resumes powering the pump motor. The off/on cycling rapidly occurs about 2

to 3 times per second, and if the blockage does not pass to return the line pressure to normal, the pump could quickly burn


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out. To prevent this, I turned to a cheap 120v to 5.5v USB adapter for a solution. I needed a signal from the pressure switch

that power was continually being given to the pump. If this 5.5v signal is lost when the pump should be on, the whole system

is programmed to shut down.

Construction was simple. The enclosure was cracked open and wires were soldered to the 120v power leads and from the

5.5v USB leads. The enclosure was resealed with marine epoxy. The finished product can be seen protruding from the

pressure switch enclosure, below. A problem appeared while testing, and it was that the charged capacitor within the USBadapter prevented the voltage from dropping by a detectable amount within the amount of time the pressure switch stayed off

in it's on/off cycling (250-500 ms). This was resolved by increasing the resistance of the circuit by incrementally adding

resistors in parallel. The resistors convert electrical energy into heat energy, discharging the capacitor. After the third 100ohm

resistor was put in place, I was able to reliably detect a drop in voltage after only three off/on cycles of the pressure switch.

This is due to the resistors dissipating the charge faster than the capacitor could recharge in the on/off cycling.


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I wrote a set of instructions to be printed and adhered to the front cover:

*-*-*-*-*-* Operation and Navigation *-*-*-*-*-*

The current time & temperature will alternate on the display by default. If the colon is

blinking when the time is displayed, the schedule is on. If the colon is not blinking and

stays solid, the schedule is turned off. While the time & temperature is being displayed.

The knob can be pressed to activate the control menu. Turn the knob to change a value,

then press to confirm the value.

*-*-*-*-*-* Menu Options *-*-*-*-*-*

1: Exit the control menu and return to displaying the current time.

2: Display schedule(s) in the format: start time, duration on, days between running, next

run day (1=Mon...7=Sun).

3: Change schedule

A: "# x" #: Which schedule, x: How many schedules to use (up to 3).

B: "XXYY" X: Starting hour, Y: Starting minute. Selecting the time will confirm &

display the next schedule time.

C: "# x" #: Which schedule, x: watering duration in seconds (~5 gallons/minute).

D: "#d x" #: Which schedule, x: how many days between running the schedule.

E: "#n x" #: Which schedule, x: Which day of the week to start schedule

(1=Mon...7=Sun).

4: Override the pump (to run the sprinkler) to either remain OFF or ON

5: Override the valve (to fill the barrels) to either remain OFF or ON

6: Turn the timer schedule OFF or ON

7: Reset the pump and valve overrides so they return to a scheduled operation (if

schedule is turned on)

8: Display temperature history over the past 24 hours, 0 is the most current temperature

stored


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-*-*-*-*-* Emergency Modes *-*-*-*-*-*

If an emergency is detected, the valve and pump will remain off until the button is

pressed to resume normal operation. During emergency mode, one of the following will

interupt anything currently being displayed:

-E-1: The valve was open > 15 continuous seconds. This indicates the water is not

activating the float switch in a timely manner. Ensure the hose going into the tank is

connected & clear, the valve is operational, the spigot is open, the tanks are free of

leaks, the float switch is free to move, and the switch is indeed activated when the

water level reaches the sensor.

-E-2: The pressure switch began rapidly turning on and off or the pump has run dry. This

indicates there is too much pressure building in the pump outlet or no water at the pump

inlet. Ensure the outflow hose from the pump is not kinked, the sprinkler screen/heads

are clean, and there is an adequate amount of water reaching the pump inlet.

-E-3: The float switch has been activated after more than 3 minutes from when the end of

a scheduled watering. This indicates there may be a leak or water is being manually

removed via the barrel's spigot. If the barrels were allowed to fill, which could takeover a minute of the valve turning on and off [to equilibriate the water levels], the

float switch should not activate this late. If water is being manually taken out,

remember to exit emergency mode in order to resume the schedule.


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Now that the circuitry is complete, I can focus on the water storage and delivery system. The general idea is that water will

enter one 55 gallon barrel by flex tubing from the gutter, a hose connecting the two barrels near the bottom will equilibrate the

water levels, and the pump will then pressurize it back above the water line and down to a hose that runs out to a sprinkler in

the garden.


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The outflow pipe from the pump rises over the point of the highest possible water line to prevent water from siphoning out

while the pump is not running. This is only possible when a separate pipe extends from the top of the bend to allow air to be

introduced into this bend immediately proceeding the pump being turned off. This vent serves two purposes. It allows air to

flow into the top portion of the pipe when the pump shuts off, preventing the gravitational flow of water toward the sprinkler

from drawing water out from the barrel, but it also alters the water pressure that's allowed to reach the sprinkler by eitherclosing (increase pressure) or opening (decrease pressure) Ball-valve 1, diverging the flow back into the barrel so no water is

lost. With Ball-valve 2 in-line after the bend, there is now the ability to completely alter the pressure from 0% to ~100% to the

sprinkler beyond Ball-valve 2.


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A sprinkler valve fills the barrels from the spigot if the water level falls below a minimum level that is signaled with a float

sensor.


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The float sensor protruding from the barrel.


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Temperature sensor consisting of a thermistor encased in heat-shrink tubing and epoxy.


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My rain sensor is a recycled plastic water bottle nailed to a board.

It utilizes the latest stainless steel screw technology.


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...with protection from large debris.


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High-heat is required to properly solder stainless steel.

It's best to protect these connections from oxidation/corrosion. The principle behind how this works is conduction. When

there is no water in the cup, air separates the two screws. A 5 volt potential is in one wire going to one of the screws. Since

this large air gap is non-conductive, this 5 volts is not detected by the arduino from the second screw. When rainwater fills

the cap, it acts as a conductor, allowing electrons to pass from one wire to the other, completing the circuit and signaling that

it's raining.


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I'll end with a final photo of my current garden and an experiment at deterring the ravenous squirrels from digging my newly

sprouting plants. The first two weeks seem like a success with battling the squirrels. The holes that previously dug my newly-

sprouted veggies from their home can now only be found bordering the outside of the fence. Who knows what enlightenment

my great wall of wire will bring to the pea-sized brain of my backyard squirrels. All I know is if they do become smarter to

circumvent my deterrent, I'll just have another project on my hands.


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I hope this has served as entertainment, inspiration, or a practical how-to for your own garden project.

18 comments:

Frankstar Mar 29, 2012 07:28 AM

wow nice :) i like it !

Reply

Anonymous Mar 29, 2012 07:40 AM

Great pictures, awesome project
http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333032056930#c2412622178846611223http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333031332000#c2232879860405666961http://www.frankstar.at/


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Kiz Mar 29, 2012 10:59 AM

Thank you. Quality photos, I believe, are the best part of a well-documented project.

holla2040 Mar 29, 2012 08:39 AM

Awesome, I love the walwart mounting. Did you see my WarmDirt project? http://www.spudcentral.com/potd/120318.html

Reply

Kiz Mar 29, 2012 10:40 AM

Thanks. I'll have to look at it more carefully later, thanks for the link.

Heather Mar 29, 2012 08:50 AM

Haha! Take that, Squirrels!! You've done such an amazing job Kyle!


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Kipple Mar 29, 2012 11:31 AM

I am interested in your pressure control system - can you post a schematic about the vale the water divergence back into

the barrel as a means to control pressure with constant pump output. I have seen PWM pump control solutions with

heavy industrial triac but at 9Amps I prefer the constant speed approach - just like in aviation the constant speed prop

has proven superior any time there are engines involved...

Reply

Kiz Mar 29, 2012 06:54 PM

I've amended the build information to include a schematic and explanation of my simple yet elegant pressure

control system. The past few months I've been exploring the options of motor controllers and such, then one

day this solution hit me.

Kipple Mar 30, 2012 11:13 AM

Beautiful! Thanks. Boy and I was suspecting some super duper tri-pipe ball valve that redirects flow on a 90

degree scale of rotation... LOL Great solution. Thank you.


Awesome project man, but why the messy arduino job, just adding a wingshield would lower the chance of wandering

wires significantly http://www.sparkfun.com/products/9729

Reply

Kiz Mar 29, 2012 02:49 PM

I've made my own shields in the past for ease and security of wiring, but I found that in enclosures like this that

are completely sealed without the possibility of wires being pulled or shaken (the whole box is screwed to the

wall), everything stays fairly well-put. The 180degree bend that some of the wires have before going into the

arduino, along with their contoured shape that runs along the back of the box, makes them rather secure as

well. Also, after using the $100 I won from this year's Sparkfun Free Day and investing money into this project, I

needed to cut the cost somewhere, so I tried to do all this with the necessities... Did I mention I'm a college

student? I may not be starving, but I am getting by with a minimal amount of loans.

Cameron Charles Mar 29, 2012 07:00 PM

Very nice!

Reply


Very good project.

You inspired me for doing something similar...

Thank you!

Are you a Greek?

Reply
http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333096974910#c6913714194689892767http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333072829285#c198456547059753866http://www.blogger.com/profile/06289984862807761714http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333057743480#c3330032768413919118http://www.blogger.com/profile/07523318746646153407http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333045918325#c4584420508198067941http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333131210006#c3368787914699023234http://www.blogger.com/profile/00705588287518240354http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333072461278#c7156758686421282398http://www.blogger.com/profile/07523318746646153407http://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333045879646#c4912023349563751785http://www.blogger.com/profile/00705588287518240354


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Kiz Mar 30, 2012 08:20 AM

Thank you. I'm glad I could help.

If you want to discuss anything, you know where to find me.

Greek? no, at least not that I'm aware of. Why do you ask?
http://autodidaktosanthropos.blogspot.com/feeds/7472430212378089043/comments/defaulthttp://autodidaktosanthropos.blogspot.com.ar/http://autodidaktosanthropos.blogspot.com.ar/2011/07/stillduino-v2.htmlhttp://autodidaktosanthropos.blogspot.com/2012/01/irrigation-timer.html?showComment=1333120816807#c1848201700218856541http://www.blogger.com/profile/07523318746646153407

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