How to make a tail wag randomly

This might sound like a weird title, but hear me out. I am working on a project called “piggy bank” my idea is to have an anonymous animal (no specific animal, just an animal) which can:

1)wag it’s “tail” randomly throughout the day, basically to say, “hi I’m here, don’t forget me”

2)Wag it’s tail when you drop a coin in.

Ideally this would have three randomly generated factors that come together: random speed of tail, random length of tail wagging, and random frequency of tail wagging (40 minutes later, then 10 minutes later, then 30 minutes later)

I currently see it as two systems: dropping the coin in causes reaction, and random timer causes reaction.

I need to figure out the driver (aka programming and the like) and the motor (wagging tail)

I now have to make a working prototype and am currently looking for ways to realize all of these things and none of the specifications are set in stone so if you have an ideas or links on how to do any part of it could work I would be greatly indebted to you.

Any ideas???

Hey man,

I’m always down to help- but this sounds like you’re asking someone else to do your job for you. I’ll create the whole system, but I’ll do it by the hour.

There’s really no pointers here - a whole system design, problem solving, more or less a start to finish design.

For example, find a cheap small motor that meets your unique specs (weight of tail, distance of wag, speed, reliability, cost, availability, force, etc should all be considered), find a cheap small power source (watch batteries for example), use some form of switch, decide how random each ‘wag’ should be (if it wags ten minutes after it just wagged I would attack), etc… all easily said. not so easily done on a web forum.

Thanks for your input. I know it sounds like a lot, but that’s because I am quite a beginner at this kind of thing, and because I really only have to make a working prototype, not a production ready design. I thought I would send the question intp the void and see if anyone knew.

Anyway, I have now decided to use an Arduino controller board to do the programming, and am now looking around for sensors and motors etc.

Anyhow thanks for the help.

Check out the Arduino board. It’s a good place to start learning how to do it on your own. You can do crazy stuff with this thing.

A CPU is probably overkill for this project. Some discrete logic with a handful of states will probably suffice. An analog timer can be constructed from a current source charging a capacitor. Vary the capacitance to change the time.