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Cat collar

flippineck

Sep 8, 2013
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Had a cat run over not too long ago :-(

I had the idea of winding a suitable coil onto a cat's collar, feeding it's ends across a bridge rectifier, and using the bridge DC output to charge a capacitor or small rechargeable cell, which would then power an LED attached to the collar. The hope being, the coil would pick up enough stray EM / radio waves to keep the capacitor or cell sufficiently charged to make the LED glow more or less permanently during the darkness hours.

I'm thinking I'd have to arrange for the coil to be tuned optimally to pick up the best of whatever EM frequencies it's likely to encounter (maybe encourage the cat to sleep next to a power socket!), and the rectifier would have to have low forward voltage thresholds. Or maybe I'd be better with a purpose made power harvesting chip? Maybe I would need some form of 'super' capacitor?

It might be good to have some sort of light sensor to stop the LED discharging the power storage when it's daytime. And maybe use a slowly flashing LED to save power.

The only design goal apart from it being acceptable to the cat, would be that a car driver at night would stand a good chance of seeing the blink of the LED from a good distance.

Is it a practical and mathematically sound prospect to pursue with commonly available cheap components?


I was looking at a 1.8V 2mA 84mW 180millicandela LED.. not sure if that would be bright enough or not
 
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Bluejets

Oct 5, 2014
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Go directly to jail, do not pass "go" ....do not collect $200.....
 

kellys_eye

Jun 25, 2010
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Had a cat run over not too long ago :-(
Sad fact of life - cat will do what a cat wants to do and no amount of lit-up collars will stop a car killing a cat that runs under it. Speaking as someone who has four cats (and has done for the last 20 years, only one of which was ever killed by a car).

Cats are naturally car-cautious but you can't train a cat to not run under one when scared or being chased by something else or just by being plain dumb.
 

flippineck

Sep 8, 2013
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I did suspect I was leading with the chin on this one :-/

Just interested if anyone could point out in any detail, the pitfalls, without resorting to ad hominem..
 

kellys_eye

Jun 25, 2010
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if anyone could point out in any detail, the pitfalls,
<my bold>

To beam enough power at the collar to make it work would be to fry the cat from the inside.

Google 'joule thief' and build a battery powered one that will last a 'long time' if you feel you must take this route. Bear in mind that LED's are notoriously narrow beam (a few degrees 'off angle' and you don't see a lot of light) so any collar would need a string of them thus making the idea yet more complicated.

If there was any merit to it then it would be available as a ready-made product - have you look for anything like it online?
 

flippineck

Sep 8, 2013
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Yes I found plenty of battery powered and USB rechargeable ones, even tritium powered ones online.

Catching each of our 10 cats once a day every day to change / charge collars would be too much to keep up with though, and the tritium ones are too expensive. We have cats that would almost be able to charge their collars themselves, and then cats that would take your eyes out rather than submit.

Maybe there are solar-recharged ones..

Probably just build a chicken wire fence along the roadside instead.
 

Martaine2005

May 12, 2015
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Probably just build a chicken wire fence along the roadside instead
Cats are curious by nature.
Curiosity killed the cat!.
They’ll simply scale it or look for a way out.
Perhaps modify a dogs LED collar.

Martin
 
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