help dog get out - newbie project review

Hello all. Help please!!
I could really use any suggestions about this project. I've never built an electronic project, but understand basic electricity, can solder, have wired
some of my house and home intranet, have moderate mechanical skills, and have 20+ years professional programming experience in various BASICs and in research.
The dog now needs out hourly instead of just before and after work. This is causing great stress, so we're looking for a fast solution (that's not too expensive). Commercial units to let the dog open our sliding glass door range from $400 for one that won't fit our situation to $1600 that will do the job, but all need weeks to deliver. (Non-electric units aren't readily available or won't keep the riff-raff, i.e. cat, out.)
Here's my idea ...
- Use a junkyard auto window lift to open and close slider; I seem to remember a unit that uses a ladder-shaped plastic chain or belt that I thought I could easily tie 1/16 inch cables to either end of.
- Motor would open door, pause 2-5 seconds, and close.
- Mount motor at opposite side from slider opening; cable end 1 goes to near bottom corner of slider to pull it open; cable end 2 goes up and around through 2 pulleys to top far side of door to pull it closed.
- Train dog to push foot switch on inside or outside to trigger open/close event (this is an extension of her sign language for going out); later, to help keep out the riff-raff, add capability for proximity switch ... while protecting against pooch holding the door open by sitting at door watching the squirrels.
- Put springs in cables to protect dog if she sits with tail in door; later, add safety mechanism similar to elevator door.
- Microswitches to detect when completely closed and completely open.
- Use Dept of Ed carrier and one of the Basic Stamps (which one?) that I might be able to find locally (Radio Shack), to reduce lead time, learning curve, and development time.
I'd like to begin building in a couple of days. It seems like I could do this for under $200, maybe even under $150.
Any help would be greatly appreciated. Am I even taking a reasonable approach? Thanks!
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I recall a cat flap which unlocks automatically when sensing a small radio transciever on the collar; this could be made larger for a dog! ----------------------------------------------------------------------- Ashley Clarke -------------------------------------------------------

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Ashley,
Yeah, I looked at the dog version of one like that, but it used an IR transmitter on the collar to unlock.
But, it was made for a swing door, not a sliding glass door. We don't have a swing door. And, I think if I modified the slider to hold a panel to mount the dog door in, the slider would not be very useful for us to use any more.
Good idea though, thanks.
Bruce

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if you're willing to cut a hole in the wall you can do things much easier. in between the studs is probably enough space to let a person squeeze through(usually 16"), trim and hinge space included. get an old hollow core door and some pine. cut a square hole from one stud to another, build a swinging door, add a mechanical latch, let the dog push a lever inside to unlock it, then push out. if you need time to get a way to prevent anything but the dog from getting in you can at least start by requiring that you get up to let the dog in, that's one less trip.     later add an electronic method for the dog to open the door, as well as a keypad so you can get in when the keys are forgotten inside. don't put an electronic sensor in the dogs collar, somebody, probably a child, will figure out that's where the thing is, then have a field day, likely with your soldering iron and the shiny bits of test gear on your lab bench. you could set it up so you can lock outside access off when you're not at home, somebody might hold the door when the dog passes through.     maybe set it up as an airlock, too small to hold a person without keeping at least one door open, refusing to unlock a second door.
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BS2
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Jim,
Thanks for the ideas.
I'm stuck with the slider. It's the only door option.
And, the walls are almost a foot thick, and I figured it would be difficult to execute wall-mounting without major carpentry in the winter.
I can't get up to let the dog in, because I'm not home (afraid I have to work). So the dog is alone almost 10 hours straight. So, it must operate unattended, and be reasonably failsafe.
Bruce
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dog sized litterbox definitely not an option?
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No, I'm afraid the dog would be given a pass to the Happy Doggy Farm first, where all dogs go that are not happy at home, and where they get to run free all the time, and have 24 hour attention, and lots of treats, and all their wishes come true.
wrote:

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a gearmotor, maybe a windshield wiper motor that's geared down, an arm connected to it and a cable, the cable end to the door edge, apply power till it hits a limit switch, a weight and cable to the other side of the door to pull it closed.     to keep the door from slamming you'd need a motor controller, something to feed the motor low power so it doesn't slam open and get off the track, and something to give it a slight bit of power to make it hold the door open against the pull of the weight, then pulse it with an even lower power to allow it to slowly close. you could do it with a pwm circuit, simple discrete's for sequencing the pulse widths, and a power transistor. add a strip of conductive foam to the edge, if the resistance changes then you can safely say the dog ain't outta the way and reverse the closing part of the sequence, a simple bar with switches mounted to it might work also.
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difficult
To get something quick until you find a better solution, why not make an insert? Make it just wide enough the dog can get through, and put some kind of flap at the bottom (whatever you need). The sliding door can close onto the insert. If you need the latch, you might be able to remove the existing one from the wall and put it on the outside of the insert. So your sliding door basically won't ever be closed all the way, but you can still keep the weather out, give the dog access through the insert, and yourselves access by opening the door the rest of the way.
- Owen -
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basic stamp is easy to program and interface to.
Window roller upper motors from vehicles would work nicely, but you have to give them 12 volts.... Use a PC power supply. It can power the Basic Stamp as well.
I wouldn't make the door slide open. make it swing. THere is alot less friction.
My dog bumps it's nose into the door when it wants out.....
Put a bunch of microswitches in parallel on both sides of the door. Put a piece of plexiglass over them, so when you push up against the door, at least one of the switches will activate.
BS2 will accept microswitch input easily.
have it wait for the condition of the switch being ON. Bring one of the pins on the bs2 high. have this pin connect to a transistor to amplify current, control a relay to activate the window-motor. You could do it by time, or have limit switches on the door. Either keep the relay activated for a certain amount of time, or until the limit switch is closed. have BS2 wait for 10 seconds so the dog can get through. Use another relay connected to another pin on the BS2 to reverse the window motor until it closes. You'll have to have a CLOSED limit switch and an OPEN limit switch.
You could do this for 150 and under.
Rich
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Rich,
Thanks for the tips.
Will the PC power supply provide enough power to drive the window lifts under load? Do you know how much current they draw? There's a 125V outlet nearby, so I thought I'd use a 13.5V 3A power supply from RadioShack ($42). If they draw less than an amp there's an $18 version (12V 1A).
I'm stuck with the slider, it's already there. It's pretty good quality and condition, so I thought the window lifts could handle it. Would car seat motors be a better choice?
Our dog puts a paw up and taps the door jam. I was thinking of a microswitch behind a book-sized switch next to the door or on the floor. The parallel microswitches sounds quite functional, but a bit pricey. If I had some time and know-how, it would be cool to make it a touch-sensitive switch so the pup could just use her nose. We could smear it with bacon grease for training!
Bruce

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A PC power supply can be found for cheap (free?) You would have to look at the ratings on the supply, but 1-4 amps seems about right.
Instead of a Switch, you can use a PRE-made FREE switch network! The BS2 and other micros can handle serial input. Get a PC keyboard and hang it on the door. Hook the keyboard to one of the input pins on your micro. When any key is pressed, you will get serial data to the micro. have it trigger the door to open. This would be FREE (at least where I live, you can find PCs for free), powered from a PC power supply (free), and maybe some day you could teach your dog to hunt and peck.
ww--a--nnn-tt b--aa--ll-lllll f---eee----eed m---eeee I---a--mm g--oo--i-n-gggg t-000 e----a--t t--hhhh--at s-m--all ---c--h-iiiil--d
:-)
Rich
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Related to this, does anyone have a website address for a webpage explaining ps2 data (as in the used by a keyboard) Thanks Michael

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Would an OOPic or BasicX-24 be as convenient and appropriate for this application? I got the impression that the learning curve was about the same as the Stamp but they are quite a bit less expensive ... true?
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baphensley wrote:

Why not buy a run and kennel for the dog to use during the day? No security issues and you know the dog won't wander off around the neighbourhood.
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I appreciate all the great suggestions for alternatives.
But, this afternoon I ruled out all alternatives to the monster slider as less reasonable and decided to go forward with the slider automation as planned.
I bought the "What's a Microcontroller" kit (90005) with Homework Board, cable, and installed BS2-1C.
Now that I'm committed to this path, I would appreciate any advice related to this alternative.
Tommorrow noon I plan to buy a window lift or seat motor from the local wrecking yard ($30-$50) unless I hear that there is a better choice that is readily available locally. I believe they come with integral gearboxes ... that's how I plan to use them.
I measured the pull needed to move the door, from rest and while in motion. I got 4-12 lb, depending on acceleration and where in the track it was. Got the same range when reversing. Both measurements were taken by pulling at the location I plan to connect the cable to.
With this small amount of info, does the motor selection still sound OK?
Does anyone have experience interfacing these motors mechanically? My proposed approach is to pull some steel cables, so I think I want some sort of chain that I can connect to.
Thanks again.
Bruce
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does the one you plan on using originally worked with a lead screw? if so you might find it easier to just extend the screw.
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No, it has a narrow steel cable wrapped around a pulley.
This is just perfect for my plans, since I intended to pull the door open and closed with a similar cable.
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I would probably just put in a regular two way swinging doggie door myself. As a matter of fact you could do it up fancy and use the glass panel you cut out as the swinging door too. Plus use clear or almost clear hinges like acrylic plastic, etc. A good person who works with glass could likely get the panel out in one piece from your existing picture window or sliding door. Anyway, then you have no electronics involved at all.
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