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my dogs are a little slow (or smart). Ideas and circuit help

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mramos1

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I have two dogs, that can get out of the dog door, but will not come back in as sometimes my wife closes the lock on them. I would like to make an automatic door opened.

My problem, the door, mechnical, and uC parts I can do. I can not think of a simple colar transmitter device and receiver to hook to the uC (will use a cheap AVR 1200A internal OSC etc). I thought about RF, but too many parts (and I forgot all that MANY years ago), then thought IR (but the sun will be a problem). Last thought was a 20-30Khz burst and audio pickup for receiver.

Any ideas. I want to have it also fire every 10-15 second to save battery life. 555 or transmiter OSC would be fine if soneone has done this, I would appreciate the help. I will tie the output of the RX to the uC, maybe use a hobby servor to left the flap (then then can see if the lock is off and come in..

Thanks for any ideas or the TX/RX circuits. Descrete or IC are fine. I have been out of the field for some time (15+ years, run an Internet company, so I do not do a lot of design anymore), so weak in designing with descretes (other than driving loads).
 
Nigel Goodwin said:
How about RFID tags?, no power required on the animal side.

Thought about that, rfidusa.com is my grandfather website. I thought he said they were costly, I will ask him again, maybe samples :)

I was hoping to make it slide on their colar. His are were credit card size, but I will research that one again.

Thanks for the input.
 
Have you considered attaching a magnet to their collars?

You could detect the field with either a coil (the dog would have to be moving) or a Hall effect device.
 
Nigel Goodwin said:
How about RFID tags?, no power required on the animal side.

Nigel, What exactially are RFID Cards?
I'm Guessing a Coil on a card?

How do they work?
I'm guessing a Resonant circuit?
 
My daughter had a Jack Russell very hyper-active dog. He would jump up over and over and open the door. Even if the door was already open, this dog would jump up and open it some more.
He wasn't smart enough to close it behind him. :lol:
 
chemelec said:
Nigel Goodwin said:
How about RFID tags?, no power required on the animal side.

Nigel, What exactially are RFID Cards?
I'm Guessing a Coil on a card?

How do they work?
I'm guessing a Resonant circuit?

Sort of, it uses a tuned circuit to collect power from the nearby transmitter, and transmits back it's digital signature - so it doesn't require any power supply (range is obviously very short, but that's all that's required). They have been discussed a number of times in these forums.
 
Another way to do it would be a proximity detector.

I believe they have 2 oscillators, one fixed and the other tuned by a metal plate. So when a body comes near the plate, that osc changes frequency and the freq difference is detected. I expect that the gnd line of the system should be connected to an earth stake (or perhaps the household electrical earth) in order to maximise the capacitance between the plate and the dog.

The advantage of this method is that you don't need anything on the dog's collar. Of course, the disadvantage is that it will detect people too.

There should be circuits available in a sites such as "discovercircuits"
 
ljcox said:
Another way to do it would be a proximity detector.

I believe they have 2 oscillators, one fixed and the other tuned by a metal plate. So when a body comes near the plate, that osc changes frequency and the freq difference is detected.
Train the dog to play a tune on the Theramin? :lol:
 
Yea that would be an termin not an toch plate button.

To detect animals of mumans toching a plate they use capacitive or the radio method.

The capacitive is meshuring capacietnce on the plate if there is a suden change it will thurn on.

The radio way will basicly detect anything big and conductive.Humans can be perty good antenas.So wen the plate gets toched all those radiowaves get chaneld in to that plate.Wen the cicuit senses that there are a lot radio waves coming in it will triger.This method would not work in the mide of the desert becose there there are abolutly no sources of radio waves.(In populated aras its radio over radio)

Oh and RFID is memory that is able to be read from a distance.So you can store an password in there and if the pasword match the door opens.
This is used to check packeges in some big warehuses.They put RFID tags in those big boxes and have RFIO readers on doors so they can seasaly keep track of what packege went out and what went in.
 
ljcox said:
Another way to do it would be a proximity detector.

That would be a great idea if I did not live in the woods with other fury animals. hehehe. Open door, racoon eatting their food.

I was thinking a 30K low level audio tone that pulses every 15 seconds (hope the dogs can not hear it). Maybe higher. And a mic, filter, amp to uC to a servo. Only problem is, my analog brain cells are gone.

RFID would be cool too, but costly. Anyone know of small, low cost rfid tag and receiver?
 
Tags are probobly not very pricy but the crecivers are probobly not that cheap.

Its the pricyest way but also the far most reliable one.

The transmiter idea is not that good becose you have to change baterys.

And dogs hear 30Khz.I know even an silent 20Khz tone makes dogs go nuts.
 
mramos1 said:
That would be a great idea if I did not live in the woods with other fury animals. hehehe. Open door, racoon eatting their food.
Hehehe. Open door, racoon eating your house? :lol:
 
Re: my dogs are a little slow (or smart). Ideas and circuit

mramos1 said:
I have two dogs, that can get out of the dog door, but will not come back in as sometimes my wife closes the lock on them. I would like to make an automatic door opened.

My problem, the door, mechnical, and uC parts I can do. I can not think of a simple colar transmitter device and receiver to hook to the uC (will use a cheap AVR 1200A internal OSC etc). I thought about RF, but too many parts (and I forgot all that MANY years ago), then thought IR (but the sun will be a problem). Last thought was a 20-30Khz burst and audio pickup for receiver.

Any ideas. I want to have it also fire every 10-15 second to save battery life. 555 or transmiter OSC would be fine if soneone has done this, I would appreciate the help. I will tie the output of the RX to the uC, maybe use a hobby servor to left the flap (then then can see if the lock is off and come in..

Thanks for any ideas or the TX/RX circuits. Descrete or IC are fine. I have been out of the field for some time (15+ years, run an Internet company, so I do not do a lot of design anymore), so weak in designing with descretes (other than driving loads).


i think a PIR can do the job, the hardest thing is buying a PIR package, they have a relay and you just need for a motor...
since they use from IR defferentials the sun light can not influence them
 
Sort of, it uses a tuned circuit to collect power from the nearby transmitter, and transmits back it's digital signature - so it doesn't require any power supply (range is obviously very short, but that's all that's required). They have been discussed a number of times in these forums.[/quote]

Nigel how it collects the power?
i would like to know more about its performance without any internal power supply
 
Put a honking big yagi antenna and a rotor on it to increase the range of the "crystal radio" card.
 
Here is a good, simple Proximity detector I designed on my webste.

**broken link removed**

It should work well for your dog.
 
Nigel Goodwin said:
epilot said:
Nigel how it collects the power?
i would like to know more about its performance without any internal power supply

Basically an RF tuned circuit feeding a rectifier - which is why it's short range.

so it sends a electromagnetic signal for feeding the RFID circuit?
 
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