infrared beacon for pet door

Going to have to attach a solar panel to the back.

How about a infra red reflector, so the cat has no juice at all ?? Bounce pulses off it. Its got to be special so other collars will not trip it.

How much do you charge for a nights sleep at the cat motel.

greg

Collar with a simple-minded bar code, repeating all the way around so that it isn't affected by orientation ?:-)

...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

I bet there's a market for automated dog/cat doors that just make use of the passive RFID tags that "chipped" pets already have. (Although I believe there's a handful of "popular" pet chips out there, and preferably you'd want it be be universal...)

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Thanks, I'll take a look!

Sharper Image went bankrupt back in February, although I guess it was only the "reorganization" type of brankruptcy as their web site claims they'll be back "soon." :-) (I'm not surprised -- they had shifted their focus from unique high-end gadgets to just run-of-the-mill crappy gadgets...) Brookstone and Hammacher Schlemmer still seem to be alive and well, though.

---Joel

snipped-for-privacy@zekfrivolous.com (GregS) wrote in news:ghpc7a$cm1$ snipped-for-privacy@usenet01.srv.cis.pitt.edu:

first problem is getting the IR pulse aimed towards the detector.

Beer companies hand out bottle caps with blinky LEDs in them,that run on tiny button cells for a long time;no problem switching the red LED for an IR LED. Use a 123 cell and it'd run for years.

At least RFID doesn't have to be aimed.

cis.pitt.edu:

I'm thinking that if I use three or four IR leds spaced evenly on the collar, it wont have to be aimed. Plus the IR light should be bright enough to reflect off the ground, and the detector should be very sensitive.

Lots of 'shoulds' I know but I think its reasonable.

Are you sure those blinky caps last for YEARS?

SNIP

You only need one wide angle IR led... and 1 pulse per 2-3 seconds is enough... average latency will be 1.5 seconds. Cats are quite patient....

Have you considered a strong magnet and a hall effect sensor?

shortT

With a steel door? His cat would be stuck to the door, the cat door would be open, and all the strays would be inside.

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Enjoy,

Steve Roberts

If I really had to do it, I'd use 32 khz watch crystals. They "sing" rather loudly, and have a high enough Q that just bringing one within a few feet of a oscillating one will cause it to resonate. So 4000 series cmos oscillator on the collar and another cystal on the door, loaded only by a preamp with no capacitance and maybe 10 megohms or more input impedance. You could also use a 40 khz piezo ultrasound transducer, and listen for the 40 khz version of the watch crystal.

When I worked at the university, we used all sorts of watch crystals with the can removed as various sensors, including sensing for the tips of atomic force microscopes.

or cheat and use a 4040 clocked by the 32 khz to get you a half second pulse and use it to gate a led.

Steve Roberts

Steve,

Is this for real or an interesting idea? Can I really get two watch crystals to vibrate sympathetically like that? Do I have to take them out of their cases?

to prolong battery life you could consider installing a reed swith in the pendant and putting a strong magnet near the door, you could up the signal rate then too.

that's a big cat! why do you need such range?

single pulses will be hard to detect bursts are much easier (repeat 1us 3us off 10 times instead of 10 us on)

I saw one cat door with an enlarged sill with a magnetic balance in it, any small piece of ferromagnetic material (I used a coin) would trip the balance and unlock the door

most of them work at 125 Khz and it's just the encoding that differs, it's may be possible to get a unique signature even if the makers serial number can't be decoded from the signal.

Nope, you can do it with the cases on. The crystals are under vacuum. Dont rigidly mount the sense crystal with short leads.

bench experiment.

Use two crystals from the same production lot.

One goes right into high impedance input on a oscilloscope set to a

Unit two gets a mW of drive in a cmos gate oscillator. It works better if the launch crystal is in a sine wave oscillator, but for your app, you dont care.

At 6" or of of being near each other, you'll start to see big sympathetic oscillations in the sense crystal.

It was a problem for me, as I needed to have several 32 khz crystals free running next to each other.

It can work better if the sense crystal is open cased, and our first ones were cut open by hand with a dremel tool, then we made a lathe like jig to do it.

Steve Roberts

parallax has a RFID reader for 35$ Sparkfun is selling tags for $1.25

Don't know what the range is, I suspect its the diameter of the search coil. The cat will quickly learn to twist his head around to hear a click and gain entry.

I hate feral cats, so I strongly support not feeding the strays. I had a neighbor who fed the strays, and soon there were 2, then 6, then 13 , then mega breeding. We'll see if the songbirds recover around here.

Akron, Ohio's city council are my heros. They require licensing of cats and offer free havaheart traps on loan.

Remember the kids movie about the dogs having to save the world from the evil cats at Christmas...........

This may sound cruel, but put on leather gloves, dunk the stray in very cold water for 5-10 seconds , toss them out in the cold ohio night air, they don't come back. You'll see them about 300 feet out, but they don't come near you again! It however, requires a level of body armor , planning, and nerves of steel that most people don't have. You will be holding onto a 4 legged buzzsaw that can do things never imagined in Alien Vs Predator. The neighbor kids thought it would be fun to feed their cat in my dog's house. Poor 15 year old Max didn't have a chance of clearing out the squatter. Hated to do that, but my dog has his house back.

Steve

One minor detail, leather welders jacket,faceplate, heavy leather reinforced welders gloves, watch for the rear paw coming in to get you at the juncture of the glove to the jacket. Perhaps best to have glove duck taped to jacket radiological warfare style. DONT ASK!

Steve Roberts

Water pistol with household ammonia works just ducky, and you stay out of clawing range.

Learned that clear back when I was a kid... training dogs to NOT chase cars ;-)

...Jim Thompson

Thoughts: The 32KHz oscillators... might the cat develop a ringing in his/her ears from hearing this all the time? Might make their life hell...

Re. aiming: all animal collars I've seen always rotate to one position: with the buckle down. The heaviest part of the collar always ends up at the bottom. If you make sure batteries (if you use them) are near the buckle, you're assured to control the orientation at all times.

If you're still worried about aiming, place highly reflective material, ie:

around the door (parallel to the cat's path). This would help direct the IR energy to the sensor.

Good luck.