Plants liven up any space by adding a sense of airiness and life. That is - of course - when you don't forget to water them, and they shrivel up and die. I am very bad at remembering to water plants. That is why I built this self-watering plant to do it for me. Using a soil sensor, and an Arduino-controlled water pump, I have created a system that will never forget to do it. Instead of remembering to water my plants when the soil goes dry, I only have to remember to once and a while refill the water reservoir. In this way, I have decreased my obligation to these plants and put it off to a much later date. Perhaps further iterations of this device can be connected to a rain barrel so that I won't even have to worry about refilling my reservoir, and the entire system can be fully automated.
Step 1: Go get stuff
(x1) 8" x 6" x 3" project enclosure (Radioshack #270-1809)
(x1) Multipurpose PC Board (Radioshack #276-150)
(x1) 5VDC SPDT micro relay (Radioshack #275-240)
(x1) 9V battery connector (Radioshack #270-324)
(x1) 9V battery holder (Radioshack #270-326)
(x1) 9V battery (Radioshack #23-853)
(x1) SPST micromini toggle switch (Radioshack #275-624)
(x1) 10K resistor (Radioshack #271-1126)
(x1) Size M coaxial DC power plug (Radioshack #274-1569)
(x1) Red and black 22AWG wire (Radioshack #278-1221)
(x1) 12AWG black wire (Radioshack #278-556)
(x1) Non-submersible electric water pump (via Amazon)
(x1) Water storage container with lid
(x2) 8-32 x 2.5" nuts and bolts
(x8) 4-40 x 1" nuts and bolts
(x1) 4-40 x 3/8" nut and bolt
(x4) 1/4" spacers
(x1) Wire nut
(x2) 3' - 5' plastic tubing
(x1) #8 Terminal Ring
(x1) House plant to water
Step 2: Trim the pump
Step 3: Drill or cut
Drill or cut a hole large enough to fit the nozzles through.
Step 4: Mark
Make marks in each of their mounting holes.
The pump will probably not have a mounting hole, so just make a mark on each side such that it can easily be zip tied down.
Step 5: Drill
You may need to widen the zip tie holes to 3/16".
Step 6: Drill more holes
Step 9: Start the PCB
Solder a 10K resistor to one of the relay's coil pins.
Step 10: Attach wires
Attach an 18" section of 12 AWG wire to an unused part of the PCB. Solder a 6" section of red 22 AWG wire to this joint.
Step 11: Split the wires
Split the power cord such that each conductor is its own separate insulated strand for about 6".
Repeat this process for the cord going into the water pump.
They need to be separated because each cable is being wired to a different spot.
Step 12: Wire the power
Connect one of the strands from the power cord to the common pin on the relay.
In this way, when the relay is powered up, AC power will be connected.
Step 14: Wire nut
Step 15: Prep the cords
Tie a knot in the two 12 AWG wires such that when they are passed through the remaining 1/4" hole there would only be tension on the knot (and not the circuit board) when you tug on them.
Step 16: Prepare the probes
Pass a bolt through each and fasten them in place firmly with the corresponding nuts.
Step 17: Wire the power
Unscrew the cover from the M-type plug and slide the cover onto the end of the remaining red and black wires.
Solder the black wire to the outer ground connection on the plug. Solder the red wire to the inner power connection.
Screw the cover back on.
Step 18: Install the switch
Mount the switch into the hole using the mounting hardware.
Step 19: Program
Keep in mind that you may need to adjust the trigger threshold for your particular plant setup.
Step 21: 9V clip
Step 22: Plug it in
If the Arduino lights up when you plugged in the battery, toggle the switch on the outside of the case to turn it off.
Step 23: Wire it up
Plug the black wire from the circuit board to the ground socket on the Arduino.
Plug the red wire from the relay coil into digital pin 12 socket on the Arduino.
Plug the red wire connected to the 10K resistor to analog pin 1 socket.
Plug the red wire connected to the soil probe into the +5V socket.