Archive for category: General

An LTSpice screencast using

December 2, 2009 | General | By: Mark VandeWettering

I was trying to remember how I did screencasts before, but instead discovered the interesting online service at It doesn’t require that you download any software: you can quickly record what occurs on the screen and upload it either to or their own server, and then embed in a blog post. Here is […]

Wolves And Rabbits

December 1, 2009 | General | By: Mark VandeWettering

I really like Today, they had an interesting little task, not so much for the program itself, but for what it reminded me of. But first, the task: basically to simulate a simple set of differential equations which model a predator prey relationship. It’s not that hard really, this just implements the model using […]

New Google Voice Number

November 27, 2009 | General | By: Mark VandeWettering

Courtesy of Zeid, I finally got an invite to use Google Voice. I’ll write more about this when I figure more about it, but at a minimum, it gives you a real phone number (amazingly, for free) which anyone can call and leave voice mail. You can configure it to ring a different phone (say, […]

LM3909 Oscillator

November 10, 2009 | General | By: Mark VandeWettering

I was wandering the net at random, following various links, and ended up researching a rather interesting integrated circuit that I’ve used before: an LM3909 LED flasher chip. It’s an interesting chip which can flash a regular LED with a 2v voltage drop using only a single 1.5v battery. I used to have this breadboarded […]

From the Brainwagon Archive: Silly Arduino Project #1: A Trivial Beacon

October 30, 2009 | General | By: Mark VandeWettering

One year ago tody, I tinkered together a very simple program and keying circuit to use my Arduino to send out a simple Morse Code beacon message. brainwagon » Blog Archive » Silly Arduino Project #1: A Trivial Beacon It seems like complete overkill to me to use a $30 microcontroller to do this task […]

Using the 74HC240 in radio applications…

October 19, 2009 | General | By: Mark VandeWettering

There are a number of interesting radios based upon using things like hex inverters or octal drivers as both oscillator and amplifier. In digging around, I found the most common chip used in this application is the 74HC240. Here’s a link to a page which contains many interesting links: Testes com 74HC240 Another link to […]

PROPNOMICON: From the Mountains of Madness

October 12, 2009 | General | By: Mark VandeWettering

Shifting gears a little from my normal subject matter, I’ll confess to a certain literary guilty pleasure: I like the writings of H. P. Lovecraft. I’m not saying they are the highest literature: I just find them to be an interesting style, creating a mythos that I find a compelling backdrop for a collection of […]

cpu_from_scratch [ projects]

October 3, 2009 | General | By: Mark VandeWettering

Every few months, I read about some one who embarks and completes a homebrew CPU project. A few months have gone by, and here’s another. Someday, I really, really, really am going to have to do this myself. Recently I decided to take on a very ambitious project to design my own microprocessor from scratch. […]

Bokode @ Home – Recreating MIT’s bokode tech with everyday materials

October 1, 2009 | General | By: Mark VandeWettering

One interesting paper I read from this years SIGGRAPH paper on the creation of an interesting real life tagging technology called Bokode. Here’s a DIY page detailing an implementation. It’s really quite simple (and neat!) I might have to code this together. Bokode @ Home – Recreating MIT’s bokode tech with everyday materials.

Small caution on using PyEphem…

October 1, 2009 | General | By: Mark VandeWettering

My previous post on using PyEphem to compute satellite locations was based upon my experience with the latest version ( Apparently this includes a fairly serious change to previous versions: by default my FreeBSD box seems to install still, and the next_pass method for observers doesn’t exist. So I thought I’d go back and […]

Why work for a game any company like this?

September 16, 2009 | General, Rants and Raves | By: Mark VandeWettering

This link is making the rounds of a couple of different mailing lists I’m on. Activision games to bypass consoles – News at GameSpot When he wasn’t promoting the company’s games or technology, Kotick was celebrating its laserlike focus on the bottom line. He pointed to changes he implemented in the past as being particularly […]

Project Icarus

September 13, 2009 | General | By: Mark VandeWettering

A group of MIT students did a high altitude balloon launch. That’s really not all that unusual: radio amateurs do similar launches several times per year. What is unusual is the price tag: $150 total. They used an inexpensive Canon camera running the CHDK firmware to snap images, and a cheap no-contract Motorola phone to […]


September 8, 2009 | General | By: Mark VandeWettering

HAKMEM is a legendary technical memo from MIT that’s packed full of interesting bits. On this occasion, I ran across item #175, which you can find here: HAKMEM 175 This is a little chunk of code which given an integer, computes the next highest integer with the same number of one bits. This code is […]

Dennis Ritchie Home Page

September 5, 2009 | General | By: Mark VandeWettering

Using Stumble Upon!, I, well, stumbled upon Dennis Ritchie’s page. He’s famous as the creator of C and an early influential developer of Unix. Back when I was in school, we all learned C by reading Kernighan and Ritchie’s The C Programming Language. His homepage has some nice papers about the history of Unix, as […]


September 5, 2009 | General | By: Mark VandeWettering

For some reason, I found myself looking at a rather pedestrian page about slide rules today, and it once again rekindled my interest in the closely related nomograms and nomography. I’ve mentioned them once or twice on this blog in the past, but in case you don’t know, nomograms are a computational aid from the […]