Automatic chicken coop door

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
I saw a video on youtube (http://www.youtube.com/watch?v=QwyfGqe3AsI&feature=relmfu) about an automatic chicken coop door and really liked the design. The only problem is that one can't get any help with how the electronics were designed. I have modified the design by using an HDPE cutting board that slides on ball bearing door slides like you would get from Home Depot or the like. I have all the mechanical parts ready to be installed and would like some help with the electonics. I have a basic understanding of 12v relays and would like someone to check my work and make sure that my understanding and thinking is correct. I am going to add 2 switches that are not on the drawing. One is to turn the whole system off by placing it just after the fuse and the other is a 3 position switch that will enable me to open the door, close the door, or have it in automatic mode. My other question is do I need diodes installed with this application and if so, do they have relays that have them built in? Thanks in advance, Todd
 

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williamj

Joined Sep 3, 2009
180
iflygiantrc,

This is not a new subject here, just do an onsight AAC search and you'll get tons of information about it.

If you're going to get any assitance at all on the circuit arrached you're going to have provide a little more information. What relays are you using, what you've provide doesn't shown any internal electrical connections and what is the "Night Watch" and how does it work?

williamj
 

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
I read the sticky, did the search before posting. I could not find anything like what I'm asking. The night watchman is a 12v marine grade photo electric eye (http://www.backwoodssolar.com/catalog/lights.htm it's the 4th one down). It provides power during the dark phase of the day. The relays are standard automotive relays (the mechanism is a subaru car window mechanism) If diodes have to be installed, one of the relays + and - leads on the coil would have to be changed for the diodes to work correctly? (the banded side of the diode is attached to the positive side of the coil). Todd
 

SgtWookie

Joined Jul 17, 2007
22,230
Use the limit switches to break the path of current through the relay coil, not the motors' power path. That way, power is only used when the door is moving, and the limit switches don't have to break the motors' current.
 

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
Correct me if I'm wrong but breaking the power path through the coil would send it back to the NC settings making the doors cycle back and forth till the "night watchman" went into daytime mode and stopped the relays from getting power to the coil to change the NO to closed completing the circuit. Todd
 

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
Correct. The door opens at dawn and closes at dusk automatically. The night watchman sends power when it senses darkness and cuts power when daylight is detected. That is the reason I have the NC'd contacts powering the door open and when the night watchman sends power at night it energizes the coils and closes the door. Todd
 

strantor

Joined Oct 3, 2010
6,829
Correct me if I'm wrong but breaking the power path through the coil would send it back to the NC settings making the doors cycle back and forth till the "night watchman" went into daytime mode and stopped the relays from getting power to the coil to change the NO to closed completing the circuit. Todd
yes, the way you've drawn it, that's what would happen. But, all you need to do, is run the 2 hots to the 2 NC contacts instead of one to the NC and one to the NO, and this problem will go away. You really don't want those automotive type relays staying engaged all night. They are real power hogs.
 

#12

Joined Nov 30, 2010
18,224
Here's a drawing. It can be modified in MS Paint.
Things happened while I was drawing and this isn't the latest version according to the conversation.
You wanna put the mods in strantor? I can't quite understand what you're saying.
Click on the drawing, go to the new tab, drag&drop into an open MS Paint.
Now I'm tacking on the explanation of the zener diode.
I took out 2 steering diodes because they were relics from my development process.
 

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#12

Joined Nov 30, 2010
18,224
Here's another way. Relays are active during daylight.
There are other ways to do this if the eyeball can be trusted to sink current when "off". That would eliminate the transistor.
 

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strantor

Joined Oct 3, 2010
6,829
I can't quite understand what you're saying.
Yes my response wasn't well written because it wasn't well thought out. What I was suggesting actually isn't possible. Sorry for the confusion. This is what I have come up with:


I don't know how to calculate resistor value or how to choose a transistor, but this worked in simulation. This should prevent either relay from ever remaining engaged once the full stroke has been completed in either direction. If OP is willing to do a little (little) soldering, this will save considerable energy, which is equal to $$. A wimpy solar panel could keep the battery charged.
 

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#12

Joined Nov 30, 2010
18,224
My drawing is prettier than yours is! :p

You gave me enough idea to reverse the logic so the relays are only on in the daytime. It seems you outdid me to shut them off after ANY motor stroke. I have only a pretty drawing of a second rate design. :(

Edit: You're playing with the uncertainty that the eye can sink current and its high output is within 1 Vbe of the rail. I hedged my bets by using a Darlington and a resistor, which of course depends on the current needed for the relay coils, which we don't know. I'd whine about labeling your relay terminals, but I figured it out. Very slick!

We just need to get some measurements of the eyeball outputs.
 
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strantor

Joined Oct 3, 2010
6,829
Lol, well I'll have to defer to your 40yrs of experience on the transistor and resistor.

would it be helpful if OP gave the resistance of the coils, or even just the part #?

(BTW your drawing is really pretty :))
 

strantor

Joined Oct 3, 2010
6,829
Edit: You're playing with the uncertainty that the eye can sink current and its high output is within 1 Vbe of the rail. I hedged my bets by using a Darlington and a resistor, which of course depends on the current needed for the relay coils, which we don't know. I'd whine about labeling your relay terminals, but I figured it out. Very slick!

We just need to get some measurements of the eyeball outputs.
the eye puts out 12A IIRC. I looked it up earlier but since lost the link.
 

#12

Joined Nov 30, 2010
18,224
The eye puts out 12 A in the positive direction but, does it SINK current?
That's one limit we need to either clarify or design around. (That's what the resistor is about.)
Those car relays with the 86 numbers are very common. I could probably guess at the coil resistance by looking up a random car relay but I'd rather hear that Ifly can measure them.

Little help here, Ifly...

I have a bid of "less than 200 ma" here:
http://www.the12volt.com/relays/relays.asp
 
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Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
First, I'd really like to thank all of you for all the great help and hope someday, in some way, I may return the favor. As far as the circuit and the components that it will need, I have the night watchman and the car window mechanism just like the youtube video. I was going to use car relays basically because this is simply a car window that is controlled by a photoelectric eye (as opposed to a 2 position switch) and they are cheap. I can purchase any components that is decided to make this project a success. On a separate note, I can solder very well and any circuit building that is needed is well within my abilities. Since the actual circuit needed is outside my normal knowledge base at this point in time, I'm relying on all of you for help. I really love to learn about anything that I can do or build with my hands and am going to enjoy building this door. I don't understand what you mean by "sink" current. Todd
 

#12

Joined Nov 30, 2010
18,224
Sink current: Apply 12 volts to a relay coil and connect the other end of the coil to the output of the "night watchman". Under conditions of daylight, the nightwatchman will not apply 12 volts to its output, but will it allow the relay to activate by letting the current through the coil "sink" into the ground connection of the nightwatchman?

Now, connect a relay as a load from the output of the nightwatchman to ground. Cover the eyeball and see if the output voltage is exactly the same as the input voltage. For instance, 12.3 volts in, 12.1 volts out? 11.9 volts out? Measure it.
Now, if you can, measure the current through the relay coil when it is "on".

Now, take the relay loose and measure its resistance through the coil.

ps, don't worry about paying us back. This is how nerds get their chubby on.
 

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
Ok, I understand now, thank you. I don't have any of the relays yet but I have to go to town tomorrow afternoon and can pick up a couple. I did do a continuity test on the night watchman and it has no continuancy through the load lead to the ground if that helps at all (night or day mode). Todd
 

strantor

Joined Oct 3, 2010
6,829
Oh well if you haven't got the parts yet then we can find a better way to do this. I was trying to design around what I thought you already have in hand. The fact that you can solder gives me an even bigger chubby. Do you have limit switches yet? If so, what model number and manufacturer? Are they spst or what?
 

Thread Starter

iflygiantrc

Joined Jul 30, 2012
53
The only components that I have at this time is the window mechanism and the night watchman. I don't have relays, limit switches, switches, or diodes. I can get what ever is needed from this point on. The door and window mechanism will be mounted and ready to go sometime late Monday. I'm headed to bed, I'll check back in tomorrow morning. Todd
 
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