Oddest Ball magic trick

 Having only seen the Oddest Ball magic trick in action, we're not 100% sure of what goes into it. But it's relatively simple to take a guess, and make something similar (even if it's not an exact copy).

But the basic idea is to have a long, thin "box" into which we'll have some holes, into each of which we place a golf ball (or similar-sized ball). Underneath one of the holes, we'll have a light-dependent resistor (LDR) and use this to detect whether the ball is present in the hole above.

Creating the box is relatively straight-forward: drop the design (above) onto the laser cutter and carve it out of 3mm mdf.

then quickly assemble the box and glue together using PVA glue

Some masking tape along the edges holds everything in place, while the glue dries.
Now, below the hole that will contain our red ball, we glue a small "drum" with a hole for an LDR (light dependent resistor) in the base. The idea is that when the ball is in place on top of the box, it will block all light from reaching the LDR.

When the ball is picked up, light will flood into the drum, and cause the resistance of the LDR to increase. We'll be able to detect this change in light level, using a voltage divider to create a variable "analogue" signal into a pin of a microcontroller.

When the LDR changes and we can detect that the ball has been lifted off the base, we'll generate a signal (and maybe trigger a siren or buzzer or similar alarm on the device itself).

And now for something completely different

 Just as our previous Nerd Club blog would often jump around between topics and ideas, so - it seems - this one is destined to do the same!

You see, we're still working on our Full Title electronic jousting game.
We've got some re-scaled minis (80% of full-scale from Highland Miniatures) that look much better on our jousting arena, and some different sized complete-loop timing belts (840mm and 920mm) which help improve the look and feel of things.

But the butterfly mind strikes again. And we're focussed on something completely different! (but a much simpler, smaller, self-contained project). 

For many years, a few of us have been attending the Blue Sky Music Open Mic nights, in and around Worthing. They're run by a smashing guy called Beany (and his wife Beth) and they're fantastic fun. And it's a true open-mic; not just singing, but performing, spoken word, poetry and even.... magic.

I always fancied having a go at performing some magic and have been watching a few performances from comedy magician Craig Petty. I really like his style, and love the way he goes into great depth with not just his tricks, but his performance advice too. When I invite others up to play when it's my turn to play a few songs, most open-mic jam sessions end up slightly chaotic, but we all have a bit of a laugh. So I thought I'd try something similar with a magic routine.

This one - called "Oddest Ball" - looks like a great "opener"

I love the comedy effect - and everyone immediately "gets" the gag. The only downside is that at over a hundred quid for a one-off laugh, it's a bit pricey! (I know that professional magicians "price in" how many times they get to use a prop and may come to a different conclusion).

But the hardware behind this seems pretty simple. And there's probably even a way we could improve of this - as well as produce it for a fraction of the £100+ price tag. I'm thinking of even having some kind of bluetooth-aware app running for the performance - so use the app to play some spooky "magic music" though the same P.A. system running the walk-around microphones. Then, when the appropriate ball is lifted, have the app play a loud siren/klaxon sound through the P.A. (rather than have to provide and power a built-in klaxon device).

In truth, we'll probably incorporate both.
But that's the basic idea - some hardware that can detect when a ball is lifted from above a sensor (LDR immediately springs to mind) that then triggers a super-loud klaxon sound. Nice and simple......

.... now where did I put those Arduino Mini boards that have been hanging around for the last five years or so...?