Digital Gaming Table Quick Prototype

I’ve been fascinated by the digital gaming tables I’ve seen on the net for a while now. This weekend I got the bug and decided to see what I could do with just the stuff I had lying around the house. I already had a small Ikea table and ceiling mounted projector up in the loft, so I figured I would try a top-down projection by placing a mirror in the beam path. A quick search out in the garage turned up a donor full-length mirror*. I cut it down to a decent size and proceeded to stand on a chair, holding the mirror in place to get an idea of how it would look.

It wasn’t too bad. Obviously I would eventually need to switch to a front surface mirror because I got quite a bit of ghosting, but the image was usable. Now I just needed a way to hold the mirror in place. Another rummage through the garage and I came back with an Ikea clamp-style goose neck lamp with a teeny burned-out halogen bulb. I knew it was unlikely I’d ever get around to replacing the bulb, so the lamp was harvested also**. Here’s the result:

I have checked several times to make sure the mirror isn’t getting hot, because I don’t want the glue to give way and drop the mirror crashing down on the table. No problems so far, it’s not even getting warm. Not bad for an hour’s worth of prototyping! And when I’m done, I can just un-clip the mirror, re-focus the projector and watch movies again.

*Every time I find something useful out in the garage, it reinforces my pack-rat tendencies. By this point in my life, I think it’s hopeless.

** See? There’s another one. Good thing I saved those, instead of getting rid of them!

Perl for Puzzlers

I was working on creating a puzzle a couple of weeks ago and needed sets of a dozen 5-letter words that all “interacted” in a certain way (sorry, don’t want to give away too much).  One of the software guys here at work suggested a Perl script to find sets words, specifically Strawberry Perl. I have been programming since I was a kid (basic on a VIC-20) but lately have been resistant to learning new languages because I can usually accomplish my goals with the languages I already know. This time I decided to take his advice and was pleasantly surprised with the simple learning curve and thought I’d pass on a bit of intro on how to set up and start using Perl to help create puzzles.


Portable Electrick Storage Device – Mark I

My daughter has swim meets every Saturday morning from 7am until around 1pm. During this time she is actually swimming a total of about 4 minutes, so the entire family tries to stay occupied the rest of the day. Almost every week someone complains “Oh, man! My iPod is dead!” Answering the tinkerer’s call to arms, I would like to present the Portable Electrick Storage Device Mark I:



USB Connectors

Charging my iPad


Closeup of foot

Battery and Connectors

Internal partition

The yellow piece is some scrap expanded PVC left over from a laptop desk I built for my wife a while back. The PCB is mounted to this, opposite the battery.

Partition & chamfer

The bottom of the partition is chamfered and held into place by another piece on the bottom. This lets it set into place easily, but still holds the battery in place tightly.


  • Box – $6 brand new at the local thrift store, I only added electronics and handles. (I need to head back and get a couple more!)
  • Battery – 12V 7Ah (~12 iPod charges or 3.5 iPad charges)
  • Output – 5V @ 1.5A (will charge iPad while watching video)
  • Connectors – 3x USB Type-A female
  • 3A fuse directly on battery
  • Power switch with blue LED indicator

Plans for the future:

  • “Working” steam power plant
  • Microcontroller based monitor (Battery charge level, internal temp, etc) with 128×128 OLED screen
  • Embedded wireless web server (WRT54G based)

Steampunk PDA – Again

I have been convinced to add the Steampunk PDA back to my list of projects I am allowing myself to work on, so the list currently stands as Deskpet, Mazetrix, PDA and notebooks. I ordered the accelerometers for the next 3 Mazetrix tiles (should be here Monday), and I should be building a couple of notebooks for some guys at work, but this sounded like more fun.

I have been thinking about the PDA for a week or two now, and decided to make a custom case rather than attempting to use a pocketwatch case. I picked up a 2″ brass pipe fitting from the hardware store and  started shaping it on the lathe. It should be just about the right size…

PDA Case

Steampunk PDA Case - Size Comparison

PDA Case

Steampunk PDA Case

Steampunk PDA Case

Steampunk PDA Case

Steampunk PDA Case

Steampunk PDA Case

CAD Assembly

CAD Assembly

Item 1 – I/O

Sufficient output to be “interesting”

  • Motors – move, dance, wiggle
  • Audio – At least beeps and boops,  possibly recorded audio, but no extra audio hardware (like mp3 decoders)
  • RGB LED Eyes – Maybe even moveable (if I have extra time on my hands)

Sufficient input to be interactive

  • Location sensing – using dual color sensors and a colored mat
  • Light sensors – need to know when it’s dark out, follow a light or find a dark corner
  • IR obstacle detection – don’t want to bump into stuff
  • IR homing sensor – to find the recharge station
  • Hall Effect Sensors – locate and play with toys
  • Capacitive touch sensing – how else is it going to know when it’s being petted?

Laser Cat Toy

Stuff like this usually generates the reaction “You have too much time on your hands…”

I was working on my pan & tilt for a Defconbot ( when I realized it would make a great cat toy. A PC is controlling the P&T, running a random pattern with the laser pointer.

Well begun is half done

My board showed up today from BatchPCB:

Bottom Side

Top Side

I managed to get the 3V power supply built and tested. Yay!

3V Power Supply

Tomorrow I will get someone at work to solder the processor on for me, as it is well beyond my skills (64 pin MLF).

And now for something a little different…

Looking for tiny Li-Po batteries? Try here.

P.S. I have uploaded a bunch of robot pics to my new Picasa web album here.

Spoka project – Begin

I was at Ikea the other day (they just built one in town, so i get to go all the time) and saw a rechargeable nightlight that I thought would be cool with some RGB LEDs. As I was working on the RF link yesterday, I realized that I could make a wireless, pc-controlled RGB LED light. So I headed over and picked up a Spoka from Ikea. This thing is just begging to be hacked. It comes with a 4.8V 400mA wall wart, and an internal 3.6V 550mAh NiMH battery. The silicone rubber outer cover diffuses the light nicely.

Contents Contents Nightlight Power Input

Once you get the plastic shell out of the silicone rubber cover (it takes some work), remove the bottom by releasing the tabs on either side. Then split the shell by releasing the tabs at the top (circles), and prying lightly. There are two alignment posts on each side (arrows) that are a snug fit.
Tab 1 Tab 2 Insides LED Board Switch

After a little circuit tracing, I had the schematic:Schematic I should be able to take out the LEDs and place my circuit in the same spot in order to keep the battery/AC/rechargeable portion working.
I am planning 2 RGB LEDs (That’s all I have at the moment) behind the eyes, and a red LED behind the mouth. I’ll use a small AVR (maybe a 2313) and the MirfV2 with a ceramic chip antenna for the RF.

Watson, come here. I want to see you!

I finally managed to send some data over the RF link. Somehow I managed to break the printf function, so I only saw the data on the scope as it clocked out of the transceiver on the SPI bus, but it was the correct data. Here’s a hint if you are using the NRF24L01 chip. Go to the Nordic website and make sure you have the latest datasheet. There is a step by step guide to the minimum config for enhanced shockburst mode. Once I had all of my generic SPI problems worked out, it just fell into place. Now to wrap it all up into a nice library and install it on a robot!

P.S. If the title didn’t make any sense, try here. Be sure to check out his notebook.

Next Page »