Need help selecting sensor

Hello, I want to build a indoor invisible fence. However, I don't know what kind of sensor would work. I need I sensor that can tell if my cat's collar is over a sensor on the ground, or if it is crossing a line. Also the sensor needs to be small, and under $15 and I would prefer if it was easy to use. I have a Arduino uno R3, though I would prefer not to have to use it permanently, I only have one. My OS is windows 10, and I have the latest version of Arduino software. Sorry it's a tall order!

This is a joke, right?

Um what would happen to the cat when it crosses this forcefield?

Stratosphere:
Hello, I want to build a indoor invisible fence. However, I don’t know what kind of sensor would work. I need I sensor that can tell if my cat’s collar is over a sensor on the ground, or if it is crossing a line. Also the sensor needs to be small, and under $15 and I would prefer if it was easy to use. I have a Arduino uno R3, though I would prefer not to have to use it permanently, I only have one. My OS is windows 10, and I have the latest version of Arduino software. Sorry it’s a tall order!

I am confused. Does the sensor and Arduino go on the cat? Do you want to put a wire on the floor? Under the carpet?

Paul

Sorry if I wasn't being clear. I meant that when the cat crosses the line, a buzzer on the collar gives them a mild shock. This has been tested, it's perfectly safe. I just need a sensor to tell if the cat crosses the line.

What has been tested? Are you already shocking your cat? With what? Is there just one doorway or what area are you trying to shock your cat at? What's with the arbitrary $15 limit?

You can buy invisible fences for dogs that work as you describe. I doubt they make them for cats, though.

Any solution will cost much more than $15.

Pretty sure if you just took good care of your cat, it wouldn't be so desperate to escape the torture.

Cats wander.

On my place, we sometimes lose them to coyotes.

Darn near impossible to "train" a cat, they have to be "conditioned", step on his tail enough and he will stay out from under your feet. Those invisible fence things are made for terrier size dogs, don't see why it wouldn't work for a house bound cat, I wouldn't put a collar on an outdoor cat though, they are always getting their nosy azzes into tight places where a collar might get them trapped.

Just play the sound of a can being opened on the "right" side of the fence when the cat triggers it!

Seriously this sounds like a magnetic loop antenna is used under the floor (big loop of wire) with a signal of a particular frequency (some 10's of kHz might be reasonable).

smaller loop for the receiver, tuned amplifier to boost the particular frequency, diode detector, comparator threshold...

Quite what the regulations are for "transmitting" VLF signals depend on your country, but loops like this that are way smaller than a wavelength at very poor transmitters anyway, its the near-field you are interested in anyway.

Thank you all for responding so quickly. To clarify, I need to keep my cat out of my kitchen, it does not have doors, and he likes to eat food scraps of the ground, but he has a food allergy so if he eats anything but his food, he scratches himself up really bad. When I say it has been tested, these systems are very common, and sold commercially. http://www.invisiblefence.com/solutions/indoor I want to see if I can make one for cheaper. The $15 limit is for the sensor itself. It would work something like; a sensor (under the carpet maybe) that can tell if the collar moves into the kitchen. Then the collar beeps as a warning, and if the cat keep going it gives them a annoying shock, Like one of those prank buzzers. I just don't know what kind of sensor would suit my needs. When I say I have a Arduino I don't know if someone has heard of something like this before, and knows if I need one or not. I would prefer not to have to use it, it's my only one. Thank you all.

Invisible fences have been tested, therefore you can prank shock your cat with a completely unrelated system. Are you aware how idiotic that conclusion is? You don't need to track your cat, you need a broom.

But since you'll persist with the lunacy, go look at IR transmitters and receivers. Strap one to the poor cat and the other to the doorway.

Yuo can buy simple netting gates to put across the doorway. They are usually used to keep crawling baby humans out of trouble.

Stratosphere: To clarify, I need to keep my cat out of my kitchen, it does not have doors, and he likes to eat food scraps of the ground,

When I had cats I prevented them from eating food scraps by simply keeping the place clean.

None of you understand my question. I do not mean this as a insult. Thank you for your time. Goodbye.

i do not like the idea of tasering your cat (please use a buzzer), but you could use a

-IR laser: Let it shine on a receiver, when the receiver doesn't receive, it is activated -PIR sensor: detects movement

To be sure it is your cat you could:

-press a manual button if it is you -put another laser on another height (above and down activated = human, down and not above = cat)

a laser would be your best choise, but you will need to build the sensor yourself

None of you understand my question.

We did, unfortunately, and are trying to talk you out of a bad idea.