brainwagon

It’s 3/14 again, and that means that it’s π day! Huzzah. This year, I thought I’d try implementing a way of computing π which was entirely new to me: finding π hiding inside the Mandelbrot set. David Boll made a posting back in 1991 to sci.math: I posted this to alt.fractals about a month ago, […]

Okay, I’ve been thinking (somewhat abstractly, since I have had relatively little free time lately) about what I eventually want my beacon transmitter to be. One of the issues with it is that I’d like it to be relatively autonomous and lower power: I’d like it to be able to run for weeks at a […]

My experimentation with oscilloscope displays made me wonder what the oscilloscope clock by Sparkfun/Dutchtronix used. It turns out to be a $5 dual parallel input DAC from Analog Devices, even available as a 20 pin PDIP. It can apparently do 833K samples per second, making it quite a bit faster than a conventional sound card […]

Nearly thirty years ago, I remember hacking together some simple code to display graphics on a WYSE 35 terminal. The terminals supported the TEK 4014 graphics commands to draw vectors, and I found the original “Hershey Fonts”, created by A.V. Hershey at the U.S. National Bureau of Standards, and placed in the public domain. I’ve […]

I lost the original edit to this post. Recreated. So, while watching the Oscars, I decided to hack together a simple little graphics program that would allow me to generate more sophisticated graphics for the oscilloscope. I ended up with 263 lines of code that implemented a simple matrix-based set of graphics commands. Eventually, I’ll […]

I’ve been meaning to do a project like this for quite some time. The basic idea is to write a program which can generate sounds which drive the oscilloscope in X/Y mode so that it will draw graphics on the screen. After an hours worth of tinkering: There is obviously some bugs, so I am […]

Well, the other I2C based breakout board I got from Sparkfun was for a Microchip MCP4725 DAC. It’s a 12 bit device, and will eventually do duty controlling the voltage controlled oscillator in my beacon transmitter. For tonight though, I just wanted to make sure I could program it, so I soldered on some header […]

Okay, I’ve been wanting to actually do a little radio project for a while. So, instead of cleaning and organizing my home office some more, I decided to go ahead and tack something together. So, the project I settled on was N1TEV’s “Ultra Simple W1AW Reciever” from the May 1997 QST. I had most of […]

Okay, revamped the basic idea, now using the irclib, which in spite of a lack of documentation, actually proved to be pretty easy to use. You should be able to figure out what it does, and modify it to use your own nicks and channel. [sourcecode lang=”python”] #!/usr/bin/env python import sys import os import optparse […]

Okay, it’s been a while since I posted anything: I’ve been busy with travel and the holidays, and now I’m trying to get my home office/shack setup so I can pursue some other projects. It is one of those rooms that has piles of crap, some of which I haven’t seen in years, so I’m […]

A long time ago, I wrote some code to send simple morse messages by toggling a pin of an Arduino. It could either blink an LED, or if you wired a bias resistor and transistor to it, you could use it to (say) act like a key for the FT-817. But then I lost the […]

Hope everyone has had a wonderful holiday. I must admit that my own vacation wasn’t productive in the sense of completing projects: I spent far too much time sleeping in, relaxing and playing far too much Epic Mickey on my Wii. But I have also spent some time thinking about the past year and year […]

Every once in a while, I feel like making high quality pictures of ground tracks of satellites. The Generic Mapping Toolkit is handy, especially when combined with the pyephem library. The thick line is the ground track of the amateur satellite AO-51, at any point in its next pass where it is visible from my […]

Okay, I finally found my copy of Ken Steiglitz’s A DSP Primer (a great book, but sadly more expensive now than when I got my copy) and read through the implementation of the tunable plucked string instrument. A couple of things really need to be added: first of all, I was off considerably in my […]

Tom showed me a link to The J1 Forth CPU, a very small processor which is coded in Verilog (only 200 lines!) and can run very fast on existing FPGA boards. It is quite an intriguing design. Forth is an intriguing if somewhat archaic programming language. In the bygone ages of my youth, I experimented […]