Proximity sensors, y'know, for cats!
September 15, 2012 12:17 PM   Subscribe

I'm looking for proximity trigger/sensors system with triggers are small enough to be worn by household pets, possibly attached to their collar. The sensors can be stationary and plugged into a power outlet.

Some additional details about the requirements: It doesn't have to be engineering components, if something like Lego Mindstorms can do this, that's fine. I don't need to know exact distances either , the sensor simply needs to know when the trigger is nearby, while ignoring nearby objects that don't have the trigger. I've looked up proximity sensors in various parts catalogs, but I'm not familiar enough with the terminology to know what specific sensors do, or what other components they require to function.
posted by yorick to Technology (4 answers total) 2 users marked this as a favorite
This kickstarter is still open and might fit your needs.
posted by special-k at 12:27 PM on September 15, 2012

you mean ... like a prox key fob for an electronic door lock? Because I assume you are looking at a kitty door.

have you seen: ... which have a bunch

this one works with the cat's microchip:
posted by jannw at 12:42 PM on September 15, 2012

A small RFID tag seems like the best approach. Something like the 'laundry tag' style would fit on a collar easily enough. What kind of effect do you want when the cat is nearby? If you're building a doohickey yourself, a reader from adafruit or parallax can talk to an arduino or whatever.
posted by hattifattener at 6:09 PM on September 15, 2012 [1 favorite]

As hattifattener said, this is pretty much what RFID tags are for. They're about the size of a coin and don't require any power but when they pass near a reader (typically 1 foot or so, but different readers can read different distances from fraction of an inch to many feet) it sends out a coded number. The reader can then take action based on that unique number. (So, for example, if you have one on the dog, and a different one on the cat you can have the doggy door unlock only for the dog, and the cat food dispenser only feed the cat.)

Other sensors (hall effect senors, active radio tags, NFC) either require very close proximity (inch or less) or require power on the device to transmit.

The reader has several components. An antena, usually about 3-4 inches square which activates the tag, and a tiny bit of a computer to figure out the number that it transmits. After that what happens is up to you. They're typically powered by 5v, but likely draw enough power that they would only last a few days on battery power alone.

If you're new to this kind of stuff I'd recommend Phidgets which take most of the electrical engineering out of the equation. They make a basic starter RFID kit with the reader and a selection of tags. They also have tags small enough to be places round bird legs if that's useful.

I've also used the readers sold by Adafruit and Parallax (mentioned above) and they're easy enough to use but require some external hardware to interface with. Not sure if that's one of your goals or not.
posted by Ookseer at 1:13 PM on September 16, 2012 [1 favorite]

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