Suggestions for proximity alarm circuit?

[Donny Bahama]

I have a little dog who can NOT stay out of the waste baskets. She's a sweet, wonderful little dog in all other aspects, so please, no mean/anti-dog comments. I've tried all sorts of things, including a good whack when catching her in the act. I really think it's a compulsion for my aptly named "Confetti".

What I want is a battery powered circuit that:

1. detects her presence
2. Waits briefly then rechecks (I don't want this thing going off every time I toss something in the trash!)
3. If she's still there on the second check, triggers a loud piezo screecher.
4. Shuts the screecher off after 10 or 15 seconds and resets the circuit.

I have several wastebaskets to cover, so I need to keep this as inexpensive as possible. Anything Arduino-based Arduino is not a good option.

I'd appreciate some suggestions. Thanks for your time and consideration.

 

[peter.rabbit]

If you want it to detect her presence only you'll need some sort of RFID tag based system I would think?

 

[(*steve*)]

RFID based is likely to have too short a range (I've considered using it to open cat doors and uncover pet food bowls. Longer range RFID can be fairly expensive.

 

[OLIVE2222]

Well, a short range emitter/receiver can be developed but is not that easy. Is a waste basket with a cover not suitable?

Olivier

 

[Donny Bahama]

RFID isn't going to work because the dogs don't wear collars in the house. Is there nothing that visually senses a nearby object?

I was hoping to detect, pause briefly, then redetect - then either sound the alarm or reset the circuit.

I could probably simplify it somewhat by skipping the 2-stage detection and just turning it off to throw something away. And it occurred to me that if I put a blinking LED on the one she gets into the most, then a simple circuit with a blinking LED (and no detection/alarm circuitry) would probably be enough to keep her out.

But then there's Louie... he gets into them, too. And I'm not sure he's smart enough to learn to stay away from the blinking LEDs...

@Olivier - We've used waste baskets with covers where we could, but some of these waste baskets have a very narrow form factor to fit where they need to - and we haven't seen waste baskets with lids in that shape/size. In other rooms, decor is a factor; we use wicker baskets as waste baskets.

 

[OLIVE2222]

Maybe it can be done other way around. Use any method to detect the basket filling (PIR, IR barrier..) but add a temporary alarm disabling push-button who can not be pressed by Confetti (will work for other dog's too )
Olivier

 

[kpatz]

How about an IR emitter on one side of the can and a receiver on the opposite side, facing each other. As long as the receiver sees the signal from the emitter, the alarm stays quiet. If something breaks the beam, have the alarm sound after a brief delay, a second or so, plenty of time for a piece of trash thrown in the can to clear the sensor. A 555 timer circuit can do this.

Chances are when doggie sticks her nose in the can, it'll break the beam long enough to sound the alarm.

 

[(*steve*)]

Great idea kpatz. It also gives you an alarm when its time to empty the bin.

I was thinking of 2 other ideas, probably both inferior to kpatz's. But I'll float them anyway.

If the dog is small enough that it has to reach up and place its paws on the top of the bin, you could have a pressure sensitive rim or ledge that will close a switch (you may need several switches mounted around it) when weight is placed on it.

If the bin is metal, you might be able to use a technique similar to touch lamps to detect a change in capacitance, or a leakage current when the dog touches the bin (this assumes that the top of the bin is open and that you drop things in). However, you would also have to ensure that the rubbish you place in the bin doesn't trigger it either.

I think it's pretty obvious that the triggering is the hard part. The other various delays are a lot more straightforward.

 

[Donny Bahama]

Thanks a lot, friends! kpatz, I really like the IR idea. I think in most cases, we could set that up so that the dogs would trigger it as they approached the waste basket. And my wife and I, knowing where the IR beam is, could avoid it when throwing something away. Now I don't need any fancy timer circuits (except to reset the alarm after a few seconds) - the alarm gets triggered the instant the beam is broken.