Archive for May, 2007

Pdxbot.07 recap and my 3 day drawing arm.

Wednesday, May 30th, 2007

There is something perverse about creating an event and then winning it.
It seems as thought Thomas, Jason, and I along with a few other dorks put in more hours in meetings, creating art and preparing for pdxbot.07 than pretty much any of our personal projects let alone anything that we could have brought to it.

In addition to representing dorkbot at the event and sponsoring the artbot competition Jason did the logo design and we collectively then created the awards and tee shirt designs for this year. The parts people seemed to be happy but I think it wore us a bit thin.
Two weeks before the actual event I lost a production server at work and wound up pulling an 80 hour week. Even so I started a framework for what will eventually be my virtual drummer.

I was going to try to get it to paint with a brush but work ate the time I would have needed to get a functioning wrist and elbow.

With 3 days to go I pulled a project from out of my drawing arm series and armed with 3 servos a chunk of brass and about $30 bucks worth of carbon rods I managed to have the hardware done the morning of the pdxbot.

On little sleep and with my son I made it to the ‘bot with a tarp in case of real entrants to the artbot competition, and of course my drawing arm. Many calls were made to Jason and Thomas for coffee and thanks to them there was coffee. When we got there Steve (where the hell is … HEY STEVE!!! ) Davee had already arrived with boxes of junk for kids to make art bot’s.

We set up and I wired my arduino up to my bot. After an hour or two of futzing I finally had motion. Which of course brought the usb powered board to its knees. Fortunately for us thomas was prepared with his network slug and soldering iron but unprepared to be off of the net and loaned us it’s 1 amp 5v power supply. With steves wire and thomas’s soldering iron and power supply I had sustainable motion from the bot. But my brain was fried.

Fortunately again Jason was not prepared either.

Jason fried at least two transistors on what is one of the coolest robots I have seen in a long time.

The upside is that he was able to help me code. Within an hour of the event we had a basic drawing machine. Fortunately for me. There were only 3 adult entrants.

And what have you done for the revolution today?

Friday, May 4th, 2007

Its one am and though i studied and built circuit diagrams and layed out the parts and I went to work and communicated and wrote and coded but no arms have moved and while joints have been soldered no sound or movement has come out.

In the morning the list of shit I havent gotten done goes on.

Sorry emilliano.
/me sings in my worthless spanish

“Yo dice nada nada nada

manyana en la manyana

nada nada nada hoy!”

But what if it dont work?

Wednesday, May 2nd, 2007

A couple of weeks ago I took one of the projects that came to the meetings last year using the arduino called the bzztbomb. I am trying to take this Arduino project to the next level in two ways.

# to create a board which would cleanly amplify the sound from the arduino board as an above board add on.
# To create a low cost board which could be used to for the finished product.

The schematic for the V-1 in its current form is at
The eagle files are at

When I finished my prototype I was able to get stereo output by modifying the example sketchbook called play_melody_faded_volume but found that the sound out of the pwm volume control sounded aweful.

I started looking at filtering the output to get smooth outputs. One of the missing pieces of the documentation of the arduino AnalogWrite is the duty cycle of the timer. A web search had the timer running at everything from 400 hz to 10-32khz. Once I finally put the sketch on a scope I found that the pwm duty cycle is 2ms long.


The sound being modulated is in the range between 261(c) and 523(C) hz. which makes 500hz a very unuseful value.

In otherwords the model included in the examples doesdnt work with ardueno – 0007.