Live Wire Go Board
goban.jpg
founder: chido
depends on:
interested: pasky
software license:
hardware license:
status: active

Live Wire Go Board

Go is a super-cool ancient board game that is played with black and white stones on a square board. The point of this project is to make such a board, but one that is a bit extraordinary! The board and the stones will be conductive and when making a move, there always will be a small chance of receiving an electric shock. This should give the game a bit of a sadistic twist. ;-)

The project includes:

  • Building the board (including a box for the electronics)
  • Wiring the board up
  • Acquiring conductive go stones
  • Acquiring safe high-voltage source
  • Controlling the high-voltage source with Arduino

Quick Setup

The electric goban is on the top of the library. Be very careful when handling it or some of the wires might be damaged. You will just need to put an Arduino inside; see below for the (trivial) sketch. Connect it to the battery (9V, should be included) and then connect the four free wires to it like this:

green: +5V, white-brown: GND, brown: GND, orange: pin 12 for interrupted shocks, pin 11 for continuous shock state

(c.f. picture https://picasaweb.google.com/113346529929240846716/20110708Electric_Goban?authkey=Gv1sRgCLSa65Hh1fmQlAE#5627773462751453730)

Parts List

Box:

  • Two square plywood plates (35x35cm)
  • Four thin wooden ledges for the sides of the box (we use 7,5cm)
  • Hinges not effective due to the top cover being heavier than anticipated

Board:

  • Faux-leather go board 9×9
  • 81 nails (4,5mm head, 20mm leg, must be conductive!)

Handrests:

  • 4x Thin metal plate for the other hand (grounding) - maybe possible to build without it? investigation pending
  • 4x LED diode (indicator of shock)

Stones:

  • nail covers made of two different metal alloys

Internals:

  • Wiring - 81 wires (e.g. from a piece of old ethernet cable)
  • Health-safe high-voltage source ($2 shock-your-friend dealextreme merchandise!)
  • Timing and control - 555-based circuit
  • Energy source (9V battery?) + power switch

Construction

Glue the four ledges to one of the plates; attach the 9×9 board to the other plate. Nail down the 81 intersections so that the heads are on the go board (will touch the stones) and the tips are sticking out of the bottom. This should produce a nice box with the board on top and room for the electronics inside.

Wire up the nails. Get your 81 wires, roughen up the surface with sandpaper, remove the insulation from the ends, and wrap one end of each around a nail. Solder them until they are fixed. Line all the wires to one of the sides and then make them go to the bottom of the box, where you join them together using a conductive copper tape, for example.

The wires shall be connected to electrically switchable high-voltage source. We use a ripped apart shock-your-friend DealExtreme gadget (we tested sku 8572 and 8566) - after some chopping and hacking, you should end up with three leads coming off: +, - and high voltage. The high-voltage lead should be connected to the wires. The + lead should be connected to + of a ~4V battery (you can use the battery stack from your gadget). The - lead will be connected to a simple circuit that will enable us to control when is the high voltage enabled.

We were not sure what the evil black thing actually is, so we decided to design the circuit as having the logic control circuit galvanically separated from the high-voltage control circuit. This means, there is no actual electrical connection between the two. A very easy way to achieve that is to use a so-called opto-isolator. At the logic control side, there is just a led, while at the high-voltage side there is a photo-transistor that conducts electricity only when the led is lighted. So when the high-voltage should be enabled, the logic control just turns on the led. (Of course, the led and the photo-transistor are encased in a four-pin chip; the part costs 20 cents.)

(Later, we took the gadget further apart; the evil black thing is just a coil, while the tiny white thing on top of it is likely a step-up DC-DC converter. Needs further investigation.)

Unfortunately, just using the photo-transistor was not possible since it reduces the voltage too much for the high-voltage generator to work. Therefore, it just controls a second transistor which actually switches the - lead of the high-voltage source (when it gets a low-voltage signal from the photo-transistor, it connects - to the ground).

There are two extra resistors in the circuit, forming a voltage divider along the pathway between the two transistors. It allows fine-tuning the voltage on the second transistor base, therefore the amount of current the transistor allows to flow through the high-voltage source (i.e. the magnitude of the shock).

The controller used to be an Arduino with sketch:

void setup()
{                
  pinMode(12, OUTPUT);     
  pinMode(11, OUTPUT);
  digitalWrite(11, HIGH);
}
void loop()                     
{
  digitalWrite(12, HIGH);
  delay(500);
  digitalWrite(12, LOW);
  delay(1000);
}

However, Krakonos kindly rewired it to Arduino-less awe-provoking 555-based breadboard circuit on JDI2011:

Stones: Original plan was to coat ordinary plastic or glass go stones with a conductive layer using conductive paint, this has turned out to be ineffective after some reseach into the availability and properties of conductive paint. Instead, nail covers made from copper and aluminium alloy will be used. Two of them will be stuck together with their bottoms to produce a stone-shape. If made properly, the bottoms connecting sufficiently, the stone should be conductive all over its surface. Soldering seemed ineffective, lead did not stuck to the surface properly. Using a glue gun to fill both halves and then pressing them together firmly (wearing mittens prevents burned fingers) proved to be a fast and efficient method that ended up being used.

Status

The box and the board with conductive nailhead-intersections are finished. Conductive stones (42 + 42) made from metal nail covers are finished. The nails have been all wired up and connected together on a copper rail within the box.

The high-voltage source has been acquired and surrounding circuitry has been constructed (by spark and rei) and tested. It works really nice!

The high-voltage controller is tiny PCB that is really messy and has a lot of useless cruft. The power regulation does not work properly, even with maximum resistance the shocks are very intense.

The Arduino is loaded and works as supposed. Stock 9V battery has at least few hours lifetime (idle current is ~27mA, hv-on current is ~105mA).

The 555 circuit is super-ugly breadboard with wires tending to get loose on transport. Needs to be soldered on a PCB.

The board had its premiere at Deskohraní (local go tournament) in Prague, 10. 10. 2010 - and it was an unexpected success. Around a dozen people tried it out, some even daring to play more than one game. Pictures from the event

Moar pics: https://picasaweb.google.com/113346529929240846716/20110708Electric_Goban?authkey=Gv1sRgCLSa65Hh1fmQlAE

Future work:

  • Put the 555 circuit on PCB.
  • Buy a precise large-scale trimmer and find the appropriate resistance values for fully flexible shock intensity tuning.
  • Get an appropriate proper-scale potentiometer and put it on the board top/side for easy intensity tuning.
  • Get a nice-looking power switch and hook it between the Arduino and the battery.
  • Make it possible to “lock in” the top side on the box.

Further Expansions

Given that each nail is connected to a separate wire, detection of stone placement can be done this way. This could be interesting e.g. for joseki learning. The problem we cannot solve yet is multiplexing high voltage, but if shocking the subject is not required, multiplexing and precise coordinate detection should be no issue. This could enable automatic recording and digitalization of the game.

Live Wire Board elsewhere

chido has featured it in her webcomic "The Empty Triangle".

 
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