Going crazy - How does this device work?

My $0.02: The plastic box of the freezer is inside a big coil - probably just a few rounds of wire around the plastic container - which is part of an oscillating circuit. Moving, adding or removing metal objects inside the coil will detune the oscillator, which is detected and triggers the giggle. Frozen products all have a small layer of ice on it, which will melt instantly when touched. If you touch something metal, the water will conduct nicely and make your body part of the oscillator. Sounds feasible to me.

If this is true, it would have a self-calibrating time period so it does not keep giggling for too long when the stock level in the freezer changes (someone restocks, or someone buys).

However, if you put your finger on a tube, it giggles continuously until you remove your finger (I left it there 15 seconds). It stops instantly when you remove your finger. I'll have to test what happens when you take a product out of the box.

Try putting in some other metal objects, such as keys or coins.

Also, did you play with this long enough to exclude a simple random mechanism (like timing) that only appears to be correlated to touching metal objects ? Our brains are excellent at picking up patterns, sometimes even when there's just noise.

Pretty much has to be capacitive, IMO. Maybe picking up (or shunting) something with your body capacitance.

Since just putting your hand inside does not trigger it, perhaps it has something to do with the shelves? Does touching them trigger it?

Best regards, Spehro Pefhany

I picked up the pattern before larwe finished the post. It's obviously capacitive. The plastic tub is surrounded by aluminum foil (or maybe that aluminum flashing stuff), and there's a capacitive sensor from it to ground. You are a capacitor. When you pick up a metallized object, that puts another capacitor in series between you and the foil surrounding the tub.

I don't know how you calibrate a capacitance sensor that closely, and admittedly, there were varying results - but when I was in the USAF the "fuel quantity" guys were always talking about picofarads, so apparently it's possible to get pretty close. And after all, all you need is a threshold. :-)

Cheers! Rich

He(she?) should try just lowering, say, a pie tin into the bin. He(she?) could borrow one in the "baking needs" section. :-)

Cheers! Rich

Okay, another possibility, some kind of low level RF signal, and the human finger/product contact introduces nonlinearity which produces detectable harmonics.

Best regards, Spehro Pefhany

Theremin used as a trigger?

-Dave

Has Joerg been moonlighting again?

martin

There are no shelves. The freezer is just a blue plastic box with a clear plastic lid; inside it's lined with white plastic. Product is stacked up from the bottom; no shelves at all.

Could it be a camera with a computer doing some recognition? Here in Montreal in the underground city, there are several spots where a projector points on the ground, and if you walk over the projected image it gets distorted only where you step, as if it were water. It can even follow several feet and you can play this "game" where you step on things and they float away. So it's definitely doable, even routine.

I've seen this sort of thing; Toys-R-Us has something like that in Manhattan (or did last time I was in there a few years ago; time flies!). However there doesn't appear to be an aperture of any sort inside the unit. There's certainly no cable running away from it except a power cable.

the renowned "larwe" wrote

He. http://66.102.7.104/search?q=cache:cH4Z6eMfWWMJ:

So, grab a pie tin and lower it into the chamber without touching anything. If it's thereminic, that should set it off.

Good Luck! Rich

maybe theres a luaghing gnome inside ...

There's a little man in the roof over the box looking down who hits a remote 'giggle' button every time you touch certain products, and not others! Just to drive you insane! ;)

Regards,

Can you see the bottom? How do you know there is no metal in the bottom . If the cans have metal ends it would make sense that they are touching a metal plate in the bottom. It sounds like you have to actually touch something on the package that is electrically connected to the metal ends which in turn would be touching the bottom possibly through other cans.

I remember playing with capacity operated relays when I was a kid. Those were the days of vacuum tubes and the circuit used a complex coil and a triode, IIRC. I think I have seen simple circuits using a transistor, but I don't recall the details. The basic concept is that the human body adds a lot of capacitance when it touches the circuit, much more than a few tins of biscuits would. So I don't see this device needing any calibration.

Yes, I dug down to the bottom looking for some magic. It's lined with a one-piece vacuum-formed white plastic sheet.