Introduction

FON (Full Of Noises) is a festival of sound and art run in the Town of Barrow in Furness, the place where the British Nuclear Submarines are made. This year (2011) one of the projects was to transform the town's pitch an put golf course in the park into a crazy golf course for two days. Two weeks before the event I received this email from Ross Dalzie, the leader of the project:-

Design

Well I had nothing suitable ready built, and with only two weeks to go I thought it was a bit of a challenge and fun, so I started thinking about designing something with an Arduino of course. There are lots of problems to think of, high ambient light meant light sensors were difficult, it would have to withstand showers and it should be have self contained power. Also being outside sound might be difficult to hear. In the end I opted for a system that would detect when a ball had been sunk, give a visual indication and play a sound. To get round the sound volume problem, the sound would come from close to the hole, where the players would surely be when the ball was sunk. The plan was coming together, the whole thing would be contained in a box at the top of the hole pin with the speaker pointing down to avoid problems with the rain. The visual indicator was to be a spiral spinning on a disc and to cover the fact that the hole could be approached in either direction there were to be two of them. The plan was that when the ball was first detected a sound would play and the discs would spin. Then as the player removed the ball from the hole they would get a round of applause.

Creating an Arduino Hole

By Mike Cook

Implementation

So how to implement that in a hurry. Compared with some of my other projects this is a bit of a hack and hot melt glue features heavily in the final construction. I had an empty plastic 1 litre ice cream tub and I thought the frustum of a cone on a pole would look an interesting shape. In the end it just looked like a standard lamp! For the sound I had a "Sound Machine" a low cost hand held toy that produced sound effects and most importantly applause was one of them. The best thing was that it could be easily hacked and the key pads could be wired directly to the Arduino output pins. The volume was also rather good and the speaker cone was plastic so that helped with the water proofing. Two motors from old CD drives provided the motive power for the discs and an array of micro switches could detect when the ball entered the hole.

Construction

The electronics part was straightforward, One pin as an input from the ball sensor, two outputs for motors, leaving all the rest of the pins for triggering the sounds. In the end I only used 15 out of the 16 sound effects to reduce the complication of having to use the serial pins. In hindsight I could have combined the two motors to use one control as they only ever worked together but this had to be a quick hack. The fact that it was to be in the open meant to me that it had to be battery powered and to make the most efficient use of the battery it needed a switch mode regulator. The circuit is shown here but you can download a PDF of it from this Link Golf.zip, along with the software. The motors were driven by two Darlington drivers and plenty of decoupling was used to try and keep the interference out of the rest of the circuit. That is what those inductors were doing. The power supply consisted of eight rechargeable AA batteries, I used 2500 mA/h so that it could work for the two days without needing a change or recharge.

Mechanics

The Mechanically it was a bit more involved with the whole thing fitting on the inside of the tub's lid. Random holes were drilled for the speaker along with a plastic bar across it to clamp it. Also the on / off switch was fitted to the lid and a right angled bracket to hold the printed circuit board. The tub was painted white before anything else, two coats of primer and two coats of gloss paint. The gloss paint takes an age to dry and even after three days was still slightly tacky. The motors were mounted on the side, an Arduino sticker, and a tube was mounted in the middle. This tube consisted of a round tube that contained cut off discs for a hand held drill, extended by a couple of turns of polyester drafting film wrapped round the 22mm dowel rod. I used a 5' 6" length for the pin, painted white and I had the microswitch platform at the far end. This consisted of three microswitches and three weak compression springs, with a white plastic disc on top. It was held in place by a hose clamp and the sensor wire wound round the pin to the tub at the top. Given enough time I would have routed a channel up the pin, embedded the wires and used filler to cover it up. But this as I said was a hack.

Final Assembly

The spiral discs were made from foam sandwiched mounting board and were hand cut using a scalpel. Then as I did not have access to a printer I put the spirals on by hand. To do this I mounted them on our vinyl player or as they used to say "record player" and set it spinning at 33 1/3 RPM, then with a marker pen I moved from the centre outwards creating the spiral. I did this twice and filled in between the two traces by hand. This came out differently for each disc as you can see from the photographs. Finally to waterproof them I gave them two coats of varnish.Hot melt glue attached them to the motor spindles.

The whole system slotted together and I was ready to take it on site and install it with a day to spare!

Deployment

When I arrived I found the hole liners were exactly the same size as my microswitch disc and so wouldn't fit, so out with the file for half an hour. Then the hole was too small to allow the ball and the pin to be in at the same time, so I had to mount the plastic disc above the hole liner. Luckily there was some depth to the hole before the hole liner so it still looked like a hole all be it shallow.

I had described to Ross what I was doing, and he allocated me the final hole. So all set up and tested I waited for the first victim / customer. Reactions were surprisingly good. People had little expectation of what was to happen when they sunk their shot. Most jumped at surprise at the sound, saw the spinning discs and laughed. Prodded the hole with their stick and some even bowed at the applause. In short, result.