My You Don't Know Jack!^® Project!

Abstract

So, why a YDKJ project? Why not?

For years, I've enjoyed the company of friends for numerous YDKJ parties. It started simple: 3 friends hovering closely together on the couch, each with a finger poised on the keyboard. Ok, it works, but it gets cramped. It didn't take long before I decided to hack appart an old keyboard and attempt to extend the crucial game keys! I'm already enjoying the success of version 2, but this page will describe the process of developing the controller...

Purpose

To build a Jeopardy-style YDKJ game controller suitable for multi-player party action! Essentially a hacked keyboard.

Construction

Since the original game controls are limited to the keyboard, the easiest way to build a custom box would be to start with an old keyboard. At the time, I only had PS/2 keyboards available to me, so I started by disassembling one to see how it was made. It doesn't take a genious to see how it works. There's a matrix of paths leading from a circuit board. A combination of the two axes returns a character.

Version 1

The first verson of this controller was pretty complicated. Since the keyboard I used was an older PS/2 model, it required some extra circuitry to work properly.

The hand-held Q, B and P buttons were about 10 feet long, and used relays to punch the key. The keyboard matrix also had a 40-50 kohm resistance on it, but every key was slightly different. I used 8 small variable resistors, 3 relays, and an PC ATA connector to link to the actual keyboard. I also took a chance and split the PS/2 signal to run two keyboards at once. To avoid interferance, I used some diodes to keep the keyboards from interfering with each other. I also used an external 12 volt DC power supply to light up the buttons on the box.

It worked well for a while, but eventually the PS/2 port was giving me problems. The keys would sometimes cut out and require rebooting the PC. Eventually I cut the cables down from 10 to 3 feet, which helped, but I still felt a redesign would be appropriate.

Version 2

This designed worked much better, and was significatly cheaper to build. The recycled USB keyboard (one of my clients spilled coffee on it) had a much simpler circuit. Also, I can attach as many USB human interface devices to a PC as I wish, so I knew it wouldn't suffer from interferance (repeating or multiple keystrokes).

The hardest problem was finding a USB 'B' female pc-mount connector. After inquiring at every local electronics store, I finally found a small A-B adaptor which I took appart. I ran the +5V wires to an RCA jack next to plug with a resistor for a white LED to light-up the controller. Each of the Q, B and P buttons runs through a 6 foot cable, which does not seam to suffer from any problems.

All in all, this version probably cost me $20 to build, plus a few hours of labour. Version 1 probably ran close to $50. I've had requests to build more, but so far these are the only two that I've worked on. I do have most of the parts ready for a third, but I've been waiting for a good reason to improve upon this excellent model!

Results

Details...

I found some recycled keypads at my local
electronics store. Only 50 cents!

The recycled USB keyboard are wiring
mounted in a project box.

I followed the paths on the keyboard matrix
to map the specific key combinations.

The graphics are just a page printed on a
colour laser printer and taped to the box.
It took a few tries to make sure
the buttons were aligned.

The buttons are made from
½" PVC tubing, push-on
buttons and clear heat-
shrinkable tubing.

Combined with a video projector and a 72"
screen, YDKJ becomes a real party game!

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