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newbie invention question?

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mearkus

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i'm working on an invention that would require a animal(dog,cat etc.) to where small transmitter around its neck. when the animal/transmitter gets close enough to a receiver an action happens...similiar to when someone presses their unlock or disarm button for a car alarm except without a human pressing a button. what is the best kind of sensor to use for this application..i don't need a very large range only 2-3 ft.
 
Try a google search of RFID products. It similar to the tags they use in stores.
 
my neighbour did something like this. He put some kind of transmitter on his dogs collar. He then uses a reciever to operate a doggie-door.

I think he did this to stop other cats from entering through the doggie-door and going through his pantry.

I don't think it was battery powered either, idon't know how he did this but them anti-theif stickers used in supermarkets don't have one either.

...this might be able to stop cunning burglars going through your doggie-door :lol:
 
pike said:
my neighbour did something like this. He put some kind of transmitter on his dogs collar. He then uses a reciever to operate a doggie-door.

A common method for that is to have a magnet on the collar, it triggers a reed relay on the flap.
 
pike said:
It would have to be a very strong magnet I imagine.

I've never actually seen the magnet for one, but I repaired the door mechanism from one for a friend - just a wire broken off, it consisted of a battery, a reed relay, and a solenoid.
 
Nigel Goodwin said:
pike said:
It would have to be a very strong magnet I imagine.

I've never actually seen the magnet for one, but I repaired the door mechanism from one for a friend - just a wire broken off, it consisted of a battery, a reed relay, and a solenoid.

Yes but for a reed relay to work right, it needs pretty high field strength which is why in the door types, the magnet is placed very close. I can't imagine this working right on a dog collar. The dog would have to get the magnet within say an inch or so of the relay.
 
Seems to me that a grid dip (Google search "grid dip") oscillator would work well. The collar would be a passive resonant circuit, and around the doggie door you would wind a coil which is the inductor in an oscillator which is tuned to the resonant frequency of the collar. When the collar passes through the door, it "steals" energy from the oscillator. This can be detected and used to trigger a solenoid to open the door.
Don't ask me to design it, though. :)
 
Optikon said:
Nigel Goodwin said:
Yes but for a reed relay to work right, it needs pretty high field strength which is why in the door types, the magnet is placed very close. I can't imagine this working right on a dog collar. The dog would have to get the magnet within say an inch or so of the relay.

Well the one I repaired was actually for a cat, but have a look in any decent pet shop, they are freely available - but I don't know about ones for large dogs?.
 
Check out RFID - namely 134.2 Khz transponders and receivers, the transponders are as small as a cylindrical key fob and are programable with a 64 bit code ( this is helpful if you need to detect more than one, such as which animal came by at what time ?, or dispense the correct food for the animal, do not let unauthorized animals in a certain area ). Digikey electronics handels a number a of combinations of transponders, receivers and antennas. www.digikey.com
 
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