More in depth details and cost break down.
Everything used in this project is easily obtainable at your local big box hardware store, and or through eBay or similar Chinese goods site.
First we will start with the lights, I decided to go with store bought LED Screw in bulbs, 8.5w Philips A19 Soft White Bulbs to be exact, as they are really easy to get, their efficiency’s are quite high even compared to higher end COB’s such as Cree’s and Bridgelux’s, they come with their own ballasts, and they are super cheap even when comparing to lesser generic junk eBay cobs. Mine I dismantled and mounted to some old salvaged GPU Heatsinks specifically for height clearances, and to allow them to run cooler than stock, which will increase their longevity, not that it matters for $2 a bulb.
Here’s a link to a breakdown of a bulb I did for this build
8w Philips LED Light Teardown
Cooling and air circulation for the Bucket is done by one temperature controlled “thermocouple” PC Fan, specially an old Gelid Solutions silent TC 9 “92mm” I’ve had for years and used in other builds. For this build I cut down the fan housing just to make things a bit more compact and to scavenge air from the absolute top of the bucket, if mounting the full fan on the outside this isn’t needed, but I wanted to save a tiny bit of height, even though it’s unnecessary. The thermocouple is mounted to one of the heatsinks used for the LED’s which when lights are on, cause the fan to go up to full speed, and when they are off the fan scales back automatically to a lower speed because now the heatsink is cooler, this can be done with PWM fan’s like what I’ve used in my PC cases, but it’s just a simpler solution. Also the fan will exhaust through a carbon filter that has at least 2” of carbon depth to knock back smells that occur during full bloom.
Intake is handled by three passive intakes that equal just under double the area of the exhaust for ease of airflow. Now to go with that the use of the inner 2gal bucket is for two purposes, the first is to create a tray for the plants, but the second is to create a light trap, that is done by cutting the same size passive intakes on the 2gal bucket as the ones that are on the outside of the 5 gal bucket but offsetting them by 60 degrees, and the top inner seal that connects the slightly cut down 2gal bucket to the 5gal bucket is just a ring cut out of some foam board acquired at a local dollar store, and was glued in with a hot glue gun on both sides of the ring.
Light proofing apart from the light trap described above, is done first by scuffing/sanding the inside of both the 5gal bucket and 2 gal bucket, but also the outside of the 2 gal bucket, then those surfaces are painted black “Flat black is preferred” till no light can be seen when shining a light though the other side, after those are dried the inside surfaces that will be pointing towards the plant are painted with a pure flat white paint till it’s all one even coat which multiple coats will be needed, this is where you could use some mylar with some adhesive spray instead if desired, but some mylar is junk for reflectance. So when it’s all done the inside with be reflective and the area that makes the light trap will be painted black.
Electrical, if going simple this could all be done using pigtail light cleats attached to a power cord and non-dismantled bulbs taped to the outside of the bucket, with a wall mounted timer and hand watering, But were going Arduino controlled.
First lets deal with the main electrical needs and to make things clean, first I start with C14 Power socket that either has a switch attached or you attach one for ease of turning on and off everything while being plugged in, which makes things a lot easier, they can be sourced from old computer power supplies or electronics or bought new from places like eBay, after the switch this is wired out to a terminal strip where I connect two things, one is the 120v “for those in North America” or 220v outside of it, but that will feed the dismantled LED bulbs but first going through a relay, and the second will go out and feed your 12v power supply which will have another terminal strip on the 12v dc site to supply your fan with power, your DC-DC Buck converter that we will be using to supply the Arduino stuff with 5v, and your 12v valve if your using one which will run through your second relay.
The Arduino stuff is composed as follows, were using a Arduino Nano with a Micro USB connection, this is our brain, to it we have a RTC “Real Time Clock” connected using the serial input/output pins, also on the same Serial I/O pins we have our I2C LCD shield which is soldered to our LCD of choice, and our Temperature and Humidity Sensor of choice, which isn’t absolutely necessary but is a nice bonus. Also two digital I/O pins are connected to the two relay control lines, two other digital I/O pins are connected to our two momentary buttons, and one digital I/O pin is connected to our power pin of our soil sensor module, with readings being taken on an analog I/O pin, but I’ll explain this later.
Also all associated LED on the Arduino Parts have either been blacked out with paint or de-soldered for obvious light leak reasons, apart from the LCD.
Here is the code that I made for this, please credit and share as I have done here, as its meant for everyone to share, and isn’t for commercial purposes obviously.
https://github.com/MrSparkleCA/MrSparkle-ArduinoGrowController
The 2 relays will control two things, one will be for the power to your lights, and the second with be the power to your pump or valve, depending on your setup you will have to wire it to its according power sources.
The soil sensor and code took me a bit to get for longevity and error, so it’s a little trick but I’m sharing it so you avoid the errors and issues I went through, first what I’m doing with the I/O pin that feeds the VCC of the soil sensor, is making it so that the soil sensor is only ever turned on when we are taking a reading, The reason behind this is if we run power through the sensor continuously, we are in effect doing the same process that is used in electroplating materials, which causes rapid destruction of your anode side of the sensor, so it’s needed for longevity, I won’t go into the math but the sensors should last pretty much indefinitely. There is also a bit of sensor over run code that prevents watering events from happening when your soil sensor fails, which I learned the hard way.
As for the actual soil sensor probe I ended up making my own custom ones for longevity, but i used two pieces of stainless steel rod “RC axles off eBay” mounted to a non conductive separator and wired out, here’s a pic of what mine look like.
Now For control, I have very basic control, any updates such as light times or soil sensor set point changes you will need to re upload your code to the Arduino in order to change that, could those changes be done with a couple more buttons and a menu selection, definitely but I didn’t want to code that as I don’t particularly enjoy programming, and I know enough to get dirty but am nowhere near proficient, so if others would like to contribute this is where I think the first step should be.
My basic control is done by a 2 way momentary switch but can be achieved with two momentary buttons, and works like this, with one of the buttons if held down for longer than two seconds will turn on the soil sensor and display a live reading of your media of choice moisture value on the LCD, this helps with finding the optimum set point for when you want your watering event to occur, and or just checking things, and once that is found its pretty much hands off, the other button is used as a bypass switch for watering, so if your set point is a bit off and your notice your medium is a bit dry you can force a watering event for as long as that button is held down, now the actual length of time that is needed for the actual automated watering event you will have to figure out on your own, because everything from tube size, to valve/pump type, to whether your reservoir is below, above, or level with your pots come into play, but the code should have an overly safe level to start with.
Here’s a cost break down for those who are wondering.
5 Gal Bucket plus Lid $3.50 + $1.75
2 Gal Bucket $1.50
Foam Board $1
A19 60w equivalent bulbs “4 pack” $5-7
1 PC Fan 92- 120mm Free - $15
12v Power Supply at least 1A Free - $2
C14 Power Socket with Switch Free - $1.50
Wire Various Gauges Free - $4
Heat Shrink $1 - 2
Heatsink Material Free - $7
Momentary Buttons Free - $2
4 Pin Connector male and female Free - $2
Terminal Strip $1
Arduino Nano with Micro USB $3
LM2596 DC-DC Buck Converter $1
Arduino RTC $1
2 Channel Relay $1.25
16x2 LCD $2
LCD I2C Shield $1
Temp and Humidity Sensor $1.50 - $4
Arduino Soil Sensor module $1
Stainless Steel 2mm Rod “RC Axels” $2.50
Reservoir $2
Micro Pump $1.25
Tubing $2
Or
12v ½” Valve $3
Associated PVC pipe and fittings $5-10
Carbon filter materials and Carbon $5
2 Part Epoxy $2
Hot Glue Gun Glue Sticks $1
Black and Flat White Paint Free - $10
Or
Mylar Reflective Material $1 - 3
Total $40 - $100
My total was right around $40 so I put that as the base price but could be done cheaper with what you have on hand or access to.
So that I think pretty much covers it and we will discuss things further when questions arise, and were in the midst of growing.
