How effective would a rolling magnetic-sphere be inside a coil?

[GreenAce92]

We lost our cat today but I was thinking about a generator that would power a cat's gps collar indefinitely just from everyday movement. Solar panels! Ha.

I was thinking about a rolling ball inside a curved coil, that was attached to the collar. Normally in say those flashlights that you shake and it generates electricity, the magnet is a cylinder, so assuming you'd just round one of these into a ball shape the size of a pea or even smaller, and this was placed inside a coil. Obviously the rolling magnet would not always be facing into the coil as far as the magnetic field goes so it probably wouldn't always produce current when going through the coil...

Another reason this is a bad design I think (aside from being bulky) is that the cat collar wouldn't always stay in the same orientation, where ideally the peak of the curve would be towards the ground where the ball can swivel back and forth.

Thoughts?

 

[BradtheRad]

Sympathy about losing your pet. I lost a cat who was hit by a car.

I looked at pet locators and the gps type requires that you pay a monthly fee to a service.

There is the motion-powered generator inside a self-winding wristwatch.

Here is a thread discussing how to make a generator for attaching to a larger animal, so it could power a transmitter.

https://www.edaboard.com/threads/312544/

 

[GreenAce92]

I actually thought of a "passive energy" design, depending on the current draw of a GPS unit, maybe it can run on a bunch of rectennas along the length of the entire collar. Like flat antennas like those maze-looking antennas for Bluetooth.

Yeah it seems baffling but I guess when you've been a prisoner all your life getting fed expensive canned food. You'd run away first chance you get ha.

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That is an interesting thought with the piezo crystals. I thought where would the pressure come from. But the weights. Ahh.

Could possibly use static discharge or heat... Not enough of a difference probably for the heat. Just talkin' as usual.

 

[BradtheRad]

The pet locator which seemed suitable for cats, was a transmitter on the collar, which broadcasts a beacon when it receives a signal from the handheld unit. (Most of the time it's in low-power battery-saving mode.)

Then we read a meter while moving the antenna from side to side, eventually homing on the transmitter.

The description said 'customer must have a ham license to operate'. I don't have one so I didn't purchase.

 

[GreenAce92]

Like a technician class ham license? Wow that product is kind of limiting requiring the license although I suppose is it any different from a car or maybe more like an airplane.

There's a similar technique/technology for RC planes. Not sure if they require a ham license to operate.

 

[Warpspeed]

Piezo transducer would be fine until you shock load it, then it shatters. Probably o/k for an elephants neck, but cats do some pretty dramatic things like jumping out of trees.

A mass bouncing on a spring, or a pendulum might be better, because it would be more able to take shock and survive a massive overload.

You don't need a license to operate on the ISM (industrial, scientific, medical) bands, but as its free go without any policing, no guarantee of interference free operation.
Some mad scientist next door may be running some fiendish device that causes problems during a full moon.

 

[GreenAce92]

Piezo transducer would be fine until you shock load it, then it shatters. Probably o/k for an elephants neck, but cats do some pretty dramatic things like jumping out of trees.

A mass bouncing on a spring, or a pendulum might be better, because it would be more able to take shock and survive a massive overload.

You don't need a license to operate on the ISM (industrial, scientific, medical) bands, but as its free go without any policing, no guarantee of interference free operation.
Some mad scientist next door may be running some fiendish device that causes problems during a full moon.

I'm trying to picture how the mass/spring would be attached to the piezo transducer.

I'm looking at these images, maybe a see-saw lever that taps on the sensor. I've never implemented one of these before. Should watch a youtube video or something.

 

[Warpspeed]

I'm trying to picture how the mass/spring would be attached to the piezo transducer.

I was thinking more a freely sliding bar magnet mounted within a tube, between too light springs, that bounced up and down inside coils mounted around each end.

 

[GreenAce92]

Oh I can see that.

By the way our cat came back, it seems strange. Just started scratching at the door, ferociously devouring food.

 

[Warpspeed]

I am retired and do not use the car much, mainly walk to local shops etc...

Anyhow, one day opened the garage rear door and someone’s cat shot out past me at about 200 Mph.
Must have been trapped in there for three days.
As I am extremely hard of hearing, I had no idea there was a cat trapped in there.

While I often see neighbours cats prowling around, I never saw that particular cat again.

 

[GreenAce92]

I am retired and do not use the car much, mainly walk to local shops etc...

Anyhow, one day opened the garage rear door and someone’s cat shot out past me at about 200 Mph.
Must have been trapped in there for three days.
As I am extremely hard of hearing, I had no idea there was a cat trapped in there.

While I often see neighbours cats prowling around, I never saw that particular cat again.

Cat's like "Thank God!" Guess Schrodinger's cat was alive after all.

 

[BradtheRad]

That's good news.

We had one cat who disappeared in winter. I walked around the development, calling Butterscotch for two weeks, then gave up. Then he showed up again at our front window. He was a bit gaunt, but ate food with gusto. I'm certain he was trapped in a garage or shed.

Cats can go several weeks without food or water, from what I read.

 

[GreenAce92]

That's good news.

We had one cat who disappeared in winter. I walked around the development, calling Butterscotch for two weeks, then gave up. Then he showed up again at our front window. He was a bit gaunt, but ate food with gusto. I'm certain he was trapped in a garage or shed.

Cats can go several weeks without food or water, from what I read.

Wow two weeks. That's amazing.

I hear sometimes they go as far as 10 miles away from their homes. Not sure why.