I have never done an Arduino project but I have a very specific project I want to build. My problem, I have no idea where to start when it comes to what hardware to order. I would like to order the hardware prior to playing with the code so I can test it as I go.
I am trying to help my uncle design an automated system for our grain storage on our farm. We use a roof top grain dryer to dry corn after it is picked. The dryer runs for about an hour at which time someone must operate a winch to drop the grain from the dryer to the storage below, wait about ten minutes for the grain to drop, then reverse the winch to close the floor and then fill the dryer. I am looking for a system that senses a voltage drop when the dryer shuts off then operates a 1hp winch to drop the grain, then has a momentary switch we can push to reverse the winch to close the floor. It would be even better if I could add an LCD screen that would show when the dryer shut off so we know how long it has had for the grain to drop. I also want it to send a SMS when the dryer shuts off, but I should be able to do that within the software. We have a Windows based computer on site to run this.
What would I need to build this? I think I need the following, but what else or maybe better ideas.
Arduino Uno board (will this be enough?)
LCD Screen
A few LEDs
two Momentary buttons, one to drop the grain manually and one to close the floor after it has dropped
a rocker switch so we can shut off the automation if we want to just do it manually
amp sensor to sense when the dryer shuts off
two relays, one to run the winch and one to reverse it.
Anything else I would need? Be as specific as possible, you won’t offend me. Links are appreciated as well.
From your description, it sounds as if the only thing you’re automating is starting the winch. In that case you only need to detect the dryer shutting off which could probably be done with a relay across power connection.
Is there an automatic shutoff when the door is completely open, or does that have to be automated also.
Next question: if you’re automating the door opening, why not also automate it closing?
Why do you need an LCD and LEDs if you have a Windows computer controlling everything? Is there a problem with using the PC screen?
Correct, the only thing I really need to monitor is the dryer shutting off. All the dryer power is 3-phase so I’m not sure there would be a relay that could handle it. But we do have a regular 110v light hooked up on the outside of the control building that is on when the dryer is on and turns off when it goes off. I suppose I could use that wire. The only problem being if the light burns out it could cause a false drop on amperage.
There is not an automatic shutoff when the door opens. We currently use a hand winch, we just winch it until the cable has slack and stop. We will add an AC winch to the dryer to make this work. I just need the software to say something like “run winch for x seconds”.
We weren’t going to automate the closing because I couldn’t think of a good way to tell the system that the winch had reached the closed point. Currently with the hand winch, we just crank it closed until we hit the “stop clamp” we have on the wire. I wasn’t sure how I could add automation to know when the dryer doors had fully closed. Maybe some kind of sensor that senses load on the winch?? That would tell it the winch has hit the “stop clamp”.
We have a computer on site that we use as an NVR for our security system, it has a monitor but we usually have it unhooked and stowed to prevent someone from seeing it and trying to steal it. I suppose we could just leave it hooked up during harvest while we are drying the grain. The idea with the LCD or LEDs was to alert us to how long the dryer has been opened. It takes about 10 minutes for the grain to drop. So if the automation opens the dyer floor we would need to know how long it has been dropping grain. Although if we can rig up the system to automatically close the winch then it’s wouldn’t be as big of a deal. I suppose it wouldn’t be too difficult to use the PC monitor, though.
You’re focusing on the “drop on amperage” thing. That would require that you connect something inline, which is typically more difficult that connecting across something.If you put the coil of a relay in parallel with the light bulb, then the relay will close when the bulb is signalled on, regardless of whether it’s burnt out or not. The relay contacts can be used to signal that the dryer is running or not. Same thing for one of the dryer phases: put a relay across one.
If you do plan to automate the winch, please do a full safety analysis. You need to consider that the winch may need to be shut off in an emergency among other things.
What I wanted to add was that I would add an interlock so once the dryer is running, you must close a safety switch that will allow the winch to run. You don’t want someone unfamiliar to get caught by the winch running when they don’t expect it to. Also a LOUD beeper to signal when time is up would be a good idea. I’m sure you guys have way too much to do than sit around watching the timer.
And yes, now that you explain what the PC is for, an Arduino is a better idea
I like the idea of a buzzer sounding right before the winch is run, but it would be near impossible for anyone to get hurt from it running. It just mounts to the bin and the cable goes up to the top of the bin and inside to open chutes in the floor. It would be nice to have a way to manually operate the winch though, mostly for clean out. I imagine that would be easy enough with winch-in and winch-out buttons on the Arduino system.
You mentioned using a relay in parallel with the light bulb. Is there any particular type of relay I need to use? I have a very basic knowledge of relays, but not enough to know what I need.
If it helps visualize, here’s an animation of what the winch controls in the bin to drop the grain. One cable connects to a bunch of small doors in the floor that allow the grain to fall from the top drying area to the storage area below. All the moving parts, with the exception of maybe 3 feet of the cable, are enclosed and away from people.
Correct, the dryer is automated to shut off when it is done. However, I don’t want to tap into the dryer system to try to tell Arduino it’s done. I would prefer to use the light we have rigged up that is on when the dryer runs and off when it’s done. I assume then I could tell the system to watch for the light to come on (dryer on) then when the light turns off (dryer off) to run the winch, then wait 10 minutes and reverse the winch to close the dryer floor.
I like the idea of a clamp on inductor. Any particular inductors you recommend?
I think I’ll stick to just having the system signal the drop being done by a time. There are at least 20 trap doors that open to let the grain out, one may stop flowing grain while the other still has a fair amount left to drop. I would need 20 photocells or detectors, one for each door. And the environment in the dryer is pretty nasty (hot, humid, and wet). We can easily time how long it takes to drop the dryer then schedule the system to wait that many minutes before reversing the winch.
Assuming the light bulb is powered by 120VAC, then any relay with 120VAC coil will work (e.g., http://www.electronicsurplus.com/magnec … 10a-120vac). The relay is just a simple form of signal isolation: it takes the high voltage signal that powers the light and produces a contact closure that an Arduino can safely read. You can do the same thing with an optoisolator, but it requires more components and the cost ends up being close to the same once everything is factored in.
lyndon:
Assuming the light bulb is powered by 120VAC, then any relay with 120VAC coil will work (e.g., http://www.electronicsurplus.com/magnec … 10a-120vac). The relay is just a simple form of signal isolation: it takes the high voltage signal that powers the light and produces a contact closure that an Arduino can safely read. You can do the same thing with an optoisolator, but it requires more components and the cost ends up being close to the same once everything is factored in.
Thanks Lyndon!
Could I use the same relays to run the winch? In other words, does it work in reverse where it could accept a signal from Arduino to run the winch?
Thinking of using this winch - 120v, 6 amp at full load
To switch the winch you want a relay with a 5V or a 12V coil so it can be controlled by the Arduino. Note that you’ll need a power transistor between the Arduino and the relay in order to switch it since the Arduino can’t supply enough current to energize the coil.
I appreciate all the feedback. I have shelved this for now while I learn a little more about Arduino. Won’t need it until next fall anyways. I appreciate the responses. I’ll be back!
