How’s it going?
I started the idea of this mist controller on 4/20 around 9:00 am. A little history on my use of micro-controllers: Before I was sure of what I wanted to do in college, I took some electronics, radio, robotics, etc. classes. In robotics class, I was introduced to the BASIC Stamp. This was around ten years ago, and it was a good introduction to micro-controllers. I got my first Arduino in 2012. I was never able to get into Raspberry Pi, as over the years, failure rate was unacceptable. Thankfully, the OPSEPP Uno I had still worked, and I decided to bring it back into my hobby space.
My inspiration was the greenhouses in horticulture class. We used a few different ways at school to work with seedlings and cuttings. I don’t want to have to hand water what looks like a dead cutting of Vitis in 50/50 mix for 5 months. I don’t think anyone does, so we used mist technology. We used this one system for a while that had a control container with one of those pressure moisture sensors to know when to mist. Then, we had a “leaf” system that used some sort of gravity/resistance reading to know when to mist. I didn’t grow up in the 1970s, so i’ve never seen my type of controller in operation; however, they exist.
The second part of the total mist system is the irrigation. This part gave me a friggin headache, and it was one of the biggest reasons why I wanted to do this. It started long ago in my backyard garden. I wanted to bring portable mist technology in the garden where I wanted to plant a row of corn, beans, or anything really. I made this.
This setup never came to be a full system, so the mist water system was moved all over the yard. At one point it sat behind my greenhouse for at least a few years. Rewind to like 3 weeks ago, and I had my idea: make a mist controller using some spare parts. I thought that I could finish this project on 4/20, and it would be great. It took around four revisions to complete.
I knew that my Rio 2100 in a bucket wouldn’t be able to supply water to all the misters on the original setup, so I trimmed the number of misters down to four. This worked with the hose, but it was never enough pressure from the pump. So, I chopped it down to two misters. Still the pump couldn’t create fog from both. I tried 1/2 in drip supply tubing, and it still didn’t work. I began doing some research and I made this in blender.
Looking more into RO, ice makers, outdoor mist systems, I decided to take an idea from an inkscape that I made a while back.
The pumps may work for the above system and the second one is for redundancy, but I knew that I needed a higher water pressure for the mist foggers. I decided to use one of those 12v NC h2o valves with the pressure from a hose.
By changing to 12v, I had to redesign the control unit. I brought in earlier ideas to finish it up. These are HV, MV, LV modules made to work with arduino; they can be driven from a slave unit via i2c.
The LV mod was selected, because the h2o valve is 12v. I’ve been torn over using a MOSFET and flyback diode to switch the solenoid, as I have a bunch of songle opto-isolated single relays that will work. The price is around the same, unless I was going to make a run of these. I think the MOSFETs may work out to be around 50 cents cheaper. Either way, I needed the 12v power supply from LV unit for the greenhouse.
Here is the complete set.
The first thing that I had to fix throughout the revisions was getting rid of the 120v in the controller. After that, I found the photo-resistor attached to the front top left corner of the unit seemed to not want to work. It became over saturated, I guess. Anyway, here is the insides.
The photo resistor problem was fixed using a light sensor on a comparator board as seen in the center. The relay in the upper right corner is now connected to the 12v power supply and the water valve. I do not have a eagle file, as I have not learned KiCad yet. However, I do have the code for the arduino nano.
/*
Mist Bench Controller
By peat
Created 4/20/2018
Modified 5/06/2018
Two potentiometers drive the on and off time of a relay.
A photoresister causes the system to work only during daylight.
*/
const uint32_t SEC_DELAY = 1000;
const uint32_t MIN_DELAY = 60000;
const uint32_t HOUR_DELAY = 3600000;
const int relayPin = 3;
const int onTimePin = A6;
const int offTimePin = A5;
//const int lightPin = A7;
const int lightPin = 13;
const int valveOffset = 200;
bool relayState = HIGH;
int onTime = 0;
int onDelay = 0;
int offTime = 0;
uint32_t offDelay = 0;
bool lightValue = HIGH;
void setup() {
digitalWrite(relayPin, relayState);
pinMode(relayPin, OUTPUT);
pinMode(lightPin, INPUT);
}
void loop() {
lightValue = digitalRead(lightPin);
if (!lightValue){
onTime = analogRead(onTimePin);
if (onTime >= 0 && onTime <= 84) {
onDelay = 5 * SEC_DELAY;
}
else if (onTime >= 85 && onTime <= 129) {
onDelay = 10 * SEC_DELAY;
}
else if (onTime >= 130 && onTime <= 303) {
onDelay = 15 * SEC_DELAY;
}
else if (onTime >= 304){
onDelay = 20 * SEC_DELAY;
}
digitalWrite(relayPin, LOW);
delay(valveOffset);
delay(onDelay);
digitalWrite(relayPin, HIGH);
offTime = analogRead(offTimePin);
if (offTime >= 0 && offTime <= 86) {
offDelay = 2 * HOUR_DELAY;
}
else if (offTime >= 87 && offTime <= 128) {
offDelay = 4 * HOUR_DELAY;
}
else if (offTime >= 129 && offTime <= 244) {
offDelay = 6 * HOUR_DELAY;
}
else if (offTime >= 245) {
offDelay = 8 * HOUR_DELAY;
}
delay(offDelay);
} else {
delay(15 * MIN_DELAY);
}
}
I have a new seed recipe that I want to try from Plant Propagation Principles and Practices first published in 1959. The book was used for inspiration really, if the medium is too wet. I’ll probably switch to 50/50 with perlite or a 3:1 peat perlite mix. Here’s what I did use:
4.5 qt peat
4.5 qt verm
1 tbsp kelp meal
1 tbsp blood meal
0.5 tbsp lime
I’m trying veggies to start, until I can figure everything out. I put a camera in the greenhouse. Here is a shot.
I’m using jumbo six packs with some tomatoes, bell peppers, and sweet peas. The camera is nice. I have it send push notifications when there is motion to track misting. I have to put my phone on the bench when i’m working in there, because it blows up with notifications. Hope this was somewhat easy to follow, as I wrote it over a few weeks. Feel free to ask for clarification. Ask any questions, too. This continues to be a fun project.
Very smart!
