Saturday, August 21, 2010

Lego Keyboard for Electronic Organ

This morning I got a first draft of real organ software running on the 16f684 / programmable sound generator circuit I've been building. Once I got the software up and running I tested it with just a probe, then very quickly wanted a keyboard. I have plans to make a permanent one from wood and brass, but I wanted something NOW. So I spent about 20 minutes in my son's room and came up with this lego creation. The only parts not stock legos are the reed switchs and magnets for the circuits. I got really lucky and the magnets I had were a perfect press fit into the bottom of the lego keys.

I hot glued the reed switches to some poster board which I then glued to a stack of legos. A rubber band provides spring back for the keys that pivot on a lego shaft. I soldered wires from the reed switch out to a header I could plug into my bread board. When you push a key the magnet attached to it closes the reed switch beneath the key. The micro reads the state change and commands the sound generator to produce the note. Right now it only has one voice.

Here's a shot of the breadboard. The big 40 pin bug is the sound generator and the little one to the right is the 14 pin 16f684 pic micro. The board to the right is my pic programmer, and to the left is my arduino. The big battery and small board in the top right corner is my portable 5 volt power supply. With this package and my laptop I develop hardware and software while I ride the bus to work in the morning.

Sunday, August 15, 2010

Electric Organ Prototyped

A couple weeks back I bought an old programmable sound generator chip from BG Micro. I got a breadboarded circuit working this morning, using a 16f684 as a controller. My plan is to build a simple digital synthesizer, but right now it's just running a simple hard coded loop that sounds like a car alarm.

Sunday, August 8, 2010

Scrolling Sign Software for the Big Blink

While on vacation a week ago I had a chance to design, code, and test scrolling sign software for the big blink charlieplexed display I built. Here's a video of the resulting test program.

The display is memory mapped to a buffer in RAM with the main loop updating the buffer with scrolling characters, and an interrupt routine lighting the pixels. It still needs some optimization to smooth out the blinkiness, and eliminate a race condition that crashes the code after some run time, but I'm pretty happy given it only took about 8 or 9 hours work.

Detroit Maker Faire Flickr Photostream

I've posted most of my stills from the Maker Faire on Flickr. Maybe later I'll get around to posting some of the cooler video on utube. Enjoy.

Tuesday, August 3, 2010

Detroit Maker Faire Pics

On Saturday the 31st I attended the Detroit Maker Faire. It was awsome - way to much to tell, so I'll just pick a few things I really liked.

My favorite was the Iron pour - that ladel has 90 pounds of molten iron in it!

This guy built a physical drum machine from a MIDI sequencer, a highlyliquid MIDI decoder, toy motors, and junk. Coolest drum machine I've ever seen. Sorry the video is small - my camera accidently got switched to "compact" mode.

More later...

Tuesday, July 6, 2010

First Surface Mount Board

Here's a couple stills of my last build. It's a self contained audio amp based on an NJM386. I got the chip surplus (I never pay retail for anything) so I had to settle for the small outline surface mount package. I made a carrier board for the chip and free-form wired the rest of the circuit inside an up-cycled Japanese eraser box my son gave me. The whole thing is about three inches square and an inch deep, and contains everything, power supply, amp, and speaker. Now I need to make an instrument to plug into it.

The plastic didn't hold up to the drilling like I had assumed it would, and my layout wasn't real precise, so it's a little funker looking than originally planned, but I think it works ok.

Saturday, July 3, 2010

First Double Sided Board Lives!

Some time ago I purchased the Pulsar system for making printed circuit boards. Since then I've made a number of simple single sided boards then felt ready for something more complex. This is the result. Design wise it's a straightforward Charlieplex display for 9 outputs. The driver holds a 16F688 pic microcontroller. Currently the software is just running a simple test program, but it's implemented with a library that allows me to address individual pixels. I plan to use the 688's uart to stream animation to the display, along with playing animation from ram or eeprom.

Here's a still of the display and the driver unplugged - the driver is pretty light weight.

Sunday, June 6, 2010

Ann Arbor Mini Maker Faire

Yesterday my eight year old and I attended the Ann Arbor Mini Maker Faire. We both had a great time, and experienced some very cool stuff. He got to do his very first soldering, doing a great job building a Wee Blinky. I showed him how to do the the first contact, and he did the rest 100% on his own.

There were also a bunch of teams there from a robot competion. My son spent a lot of time driving some of the big 'bots around. He didn't get into the some of the smaller ones scooting around, but he really liked the big stuff.

My favorite was the juggler. She had a cigar box fanny pack on that contained four motors and a spark generator. The motor shafts had zip ties on them so when they spun they'd make a rythmic clicking. The circuits where all incomplete, with wires led up to bare conductors in gloves or rings she was wearing. While juggling, when she caught a conductive ball the circuits would be complete causing the motors to spin or the spark to spark. This resulted in her juggling being accompanied by her own cool little rythm section.

Wednesday, June 2, 2010

B.bro in action

Here's a video of B.bro drawing a very simple starburst pattern on posterboard.

Tuesday, June 1, 2010

B.bro Stills

Here's some quick shots of my robot B.bro - he's named after the character in the song "Baby Brother" by the White Stripes.

The brass tube is a holder for Sharpie pens so he can draw patterns on the floor. He's got a dead simple user interface (an LED and a pushbutton). When I turn him on he sits there and waits for me to push the button. Then he takes off and draws a simple pattern - stopping and lighting his LED when he's done. This allows me to pick him up and move him, or change pens to a different color. Then I push the button again and he takes off once more. In the near future I'll be posting some video of him in action, and technical stuff like schematics and source code. Hope you like him.

Thursday, May 20, 2010

New Year - new projects

It's hard for me to believe it's been a year since I last posted anything here. Lots has happened which will go untold. Suffice it to say I've wakened from my tech involved slumber and have some cool stuff going on.

If you're looking for an update on the NetLogo project, I had to let that one go for now. My personal journal is still open on the subject but progress is quiet and reflective.

What I've got going on now is much closer to my roots as an engineer. I'm currently working three projects:
  • Building a low cost cnc mill
  • Developing a small robot
  • Learning to hack on the road

I'll be writing about and posting pictures of each project as time allows, and as interesting things happen.

Stay tuned...