Bell for a tiny dog

peterz

I would like to have something like a passive(or almost) bell for a tiny dog.
The idea·is that·I want to hear·him approaching but·I don't want the bell ringing all the time, just when the dog is near to me, and I better if the bell ring on me, instead of ringing on the dog.
The perfect solution would be to have something passive on the dog, like a RFID, but I don't know whether this would be a suitable solution, because,·suppose the dog is·5 feet·away, would it work ? BTW, does the size of the RFID tag matter?

If an RFID is not a solution, which alternatives are there?



·

Mike Green

RFID doesn't have the range to do what you want (at least not with the units available from Parallax). How about if you wear an IR beacon that puts out a pulse of modulated IR light a couple of times a second. The dog collar would have an IR detector and a microcontroller which would verify the IR signal and sound a tone through a piezo speaker. If you want the speaker on you, you could put the IR beacon on the dog.

D Faust

FYI if you don't want to use an uController of the emmiter you can make one with a 555 timer IC.· I think there is a schematic in the IR remote book.· You might be able to eliminate the the IR detector ucontroller by having the detector pull the base of a PNP transistor low when it senses the IR.· You could use a piezo buzzer with the built in resonator things (not·the one·with the boe-bot)·so that· when you supply power to it through the transistor it beeps.· You would probably add a switch to each of these devices so that you could turn the buzzer off.

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peterz

The IR method would not work as it would require a straight line of sight. If I wear my IR emitter in my front it would not work when I am looking backwards. I would need something that works in any direction.

Mike Green

peterz,
I was imagining several IR LEDs driven by one 555 timer or several pins of a microcontroller so that they pointed in several directions. In addition, I was assuming that there'd be some reflection so the room would be filled for some distance around with modulated IR at an intensity enough to activate the detector.

PJAllen

peterz said...
I want to hear·him approaching...

Assassin Chihuahuas: If they see you before you see them --then·you're toast.

D Faust

What if you use RF.· It would be more expensive, but it would work without line of sight.· Unless this is a killer dog situation, RF is probably overkill.

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Phil Pilgrim (PhiPi)

This is probably the kind of thing you're after, except repurposed to warn of proximity, rather than a lack of proximity. I believe there are similar devices available to prevent theft of laptop computers, cellphones, etc.

-Phil