how to lift and drop a pet door, motorized, remotely

[GaS753]

I guess this would be a project or hobby type question "pepe" and I hope at at the correct place to ask it. I have a pet door that operates in a track (sort of picture a guillotine where the door is like the blade, going up to let the cats trough and down to prevent them from doing so. I would like to motorize the door and have it remotely controlled. I need some kind of a simple inexpensive circuit that would allow the door to be lifted and let the cats go through and then stop at the top of the track, and then allow the door to be lowered to close the opening so the cats are prevented from going through. Can anyone help me with this project? Thank you for your time and consideration. Sincerely, Garry.

[pebe]

Have a look here to see if it is what you want.

viewtopic.php?f=1&t=3520&hilit=chicken

[GaS753]

Thank you pebe for approving my question, though new-bee may still be out of my league as I have looked over the “chicken coop door” material you referred me to. So I have tried to use some of that formula to restate/re-ask about my project.

The pet door is positioned in the main hall way of our home to keep the dogs out of our bathroom and bedrooms - so the door is usually closed. The cats have access to those rooms, especially the bathroom where their liter boxes are positioned. Three of the cats just go up and over the gate/door but our 17 year old can’t make it any more and our 1 yr. old has a bad leg and never could jump, therefore they have to have the door opened so they can travel back and fourth. ((note: The dogs are small and would have no trouble going through the door.))

As I stated originally, the door travels up and down in a track (picture a guillotine) and I would like that to happen by motor whenever I make it happen from a remote location. The door is made of 1/4” plywood that weighs 6/10 of a pound. I am open to any solution that is inexpensive. I have used a soldering iron in the past for other projects.

I am afraid I did not understand the chicken door example as it seemed more complicated than I need with timers and all. I don’t even know if I should be using AC or DC, but to be able to reverse the direction of motor sounded like a good idea to me. Would you please furnish a list of necessary components along with you schematic.

I would like to “push a button” to raise the door clearing the opening (about 12”) and then after the cat or cats pass through to activate the door again to close.

That you very much for your time and consideration for this beginner.
Garry (GaS753)

p.s. I am resending this as I guess I sent it to the wrong place - I'm new at blogging also. Thanks again!

[pebe]

It should be a fairly easy project. But could you clarify a couple of points?

You want to keep out your dogs, but you say they are small and can easily get through the door. So I assume you will have the gate in view when you lift the door to let the cats in, you can be sure the dogs are not near. So how 'remote' does the control have to be? Can it be hard wired, or need it be by radio link?

A push button is to open the door. But how is it to close? by the same push button? By another one? Or is it to close automatically after a timed period?

[GaS753]

Certainly glad to have your 2nd response pebe, I was not sure I was using this blog correctly.

Let me try to clarify. The gate is in view from its position in the hall, across the head of the stairs, across two doorways, and the width of the living room - total of about 25’. Having to have a wire(s) lay across the stairway and two doorways and the width of the living room seems unpractical and perhaps unsafe.

So when the cat is asking to get through the opening, I am hoping we can remotely signal the door to open, then stay up until the cat is through (a few seconds), then remotely signal the door to drop back down and close the opening again.

The no. of pb’s doesn’t matter and no automatic time to stay open. As you said it is a matter of us watching.

Thank you so much for your help, I surely appreciate what your doing!
Garry (GaS753)

[pebe]

Hi Garry,

I think the simplest (and cheapest) way of doing this would be to use a remote garage door opener like this

http://www.ebay.co.uk/itm/Wireless-Gate ... 564b0692bc

For less tha £6 you would have a transmitter and receiver with a couple of change-over relays that will open and close the gate. All you would need extra are a 12V motor, a power supply, and a couple of switches as end stops to turn the motor off at the end of its travel. In fact, if you are watching the gate you can switch off the motor yourself.

I have bought and use an identical item from ebay and can recommend it. If you want to go that route then I can do you a wiring diagram.

[GaS753]

Thanks once again for your help pebe. That sounds like a good route to go but are you going to send me some guidance with what 12V motor, power supply, and switches I would need and where to find them or does that info come with the wiring diagram? Garry (GaS753)

[pebe]

I have looked for the various components for you and here is what I have found:

The motor should be 12V so it can be run from the same supply as your receiver, and needs a reduction gear to provide enough torque for your application. Here is a suitable one. It has a max torque of 60 Newton*cm. Your door only requires 3 Newtons to lift it so it has plenty of power.

http://www.ebay.co.uk/itm/25mm-12V-120R ... 46018556ea

You need a power supply with enough output to handle the starting surge current in the motor. This is a switch mode 12V 3A supply made for laptop power. Because these are made in vast quantities the price is competitive.

http://www.ebay.co.uk/itm/12V-3A-AC-Ada ... 3f1ae04684

You may have your own ideas on how to lift the door, but the chain and pulley method here would be ideal. You could Google and probably get something similar for a cheaper price.

http://cpc.farnell.com/mfa/917d-3/chain ... 5-00001003

Personally, I would use an alternative method. I think I would try using a piece of nylon blind cord fixed vertically to the door and kept in tension with a spring, with it wrapping a single turn round a pulley on the motor. Some rosin applied to the cord would help.

There are two main types of receiver available. The 'momentary' one where the relay is only changed over while the transmitter button is held in, and the other, a 'latched' type where the relay stays in until the other button is pressed, the relay drops out and the other relay comes in. The advantage of the latched type is that you only need a quick jab at the button to start the motor running, whereas the 'momentary' type needs the button to be pressed all the time that the motor is running.If you use the latched type then you need limit switches to stop the motor at the end of its travel. You can either fashion these yourself from springy brass strips, or you can use these microswitches.

http://www.ebay.co.uk/itm/AC-250V-5A-3- ... 20c9c586e9

With a 250VAC 5A rating they should be suitable to switch 24VDC.

Do you want to go ahead?

[GaS753]

Thanks for all your time and effort - it all sounds great - full speed ahead!

I checked all the sites you gave me and everything looks good and available except for the power supply - they say its all sold out but have listed “other possibilities” one which I have listed here to see if you recommend it as a substitute or not, I was’t sure if they were the same.

12V 3A 36W AC Power Adapter Charger F. ASUS Eee PC Mini Netbook/laptop New 1

http://www.ebay.com/sch/sis.html?_nkw=A ... R-CHARGER-

Product Description FOR ASUS AC ADAPTOR (NEW)
DC Output DC 12V - 3A, 1.7X4.8MM 36W MAX
AC Input AC 100-240V - 50-60Hz, 80-120VA
Color Black

I can't wait to get started, well as soon as I get your further info and drawing - Thanks so much. Garry

[pebe]

Yes, that power supply would be OK. I'll draw up a circuit for the connections.

[GaS753]

Have a related question I hope you can answer pebe. My wife looked over the paperwork and pointed out that everything I will need to order for this project appears to be distributed from warehouses in Hong Kong. Not a problem except that in eBay’s literature they state the following:

“Import duties, taxes and charges are not included in the item price or shipping charges. Buyers are responsible for these charges. Please check with your country's customs office to determine what these additional costs will be prior to bidding/buying.”
Have you had a similar situation - I can not find any info from Google searches or from any source including eBay to tell me what this is about and what’s the cost. Is this something to worry about or not?

Another worry we also noticed under the micro switches, eBay’s literature also states: “Due to Custom restrictions, we do not ship lighters to US.” I assume lighters is referring to the switches light weight and they won’t send them to me. Would you know if the switches are a part of my total order - the motor, and wireless gate switch and transmitter, and the switches will that boost them out of “lighter” category or now does one find out?

Thank you so much, and I thought I was ready to build. Garry (GaS753)

[pebe]

Hi Garry,

You appear to live in the US so I cannot really answer your questions. I live in the UK and have ordered many things from Hong Kong, including a PC oscilloscope costing £120, and I have never had to pay import tax on any of them. The items have all been of good quality and delivered promptly.

I don't know what the import tax rate is in the US, but even allowing for it, the items would still be fairly inexpensive. Alternatively, you could Google to see if similar items are available in the US. I think all the items I mentioned are free of postal charges to the UK. You can check each item advertised to see if they are post free to the US.

On the question of lighters, I think the authorities are refering to cigarette lighters because of the imflammable fluid they contain, so they would not apply to micro switches.

[GaS753]

Thanks for the above and beyond pebe. I will keep working on it and hopefully I will have what I need when your drawing arrives. I also forgot to ask about the reduction gear you mentioned. Does that come with the motor or is it something I need to get and if so can you give me some specifications and so forth?
You have been a great mentor and I can’t say enough about the time, the help, you have provided. Many thanks again. Garry (GaS753)

[pebe]

Yes, the motor has a reduction gear built in. It gives an output drive at 120rpm (2 revs a second).

[GaS753]

Pebe, you have come through again! I have managed to find 3 of the four items I need so the 4th will not be a problem. That was good news for me about the reduction gear. Thank you again for all your help. This will be a really good project for me thanks to you. Garry (GaS753)