Archive for month: May, 2011

The Broadcaster Project, revisited

May 18, 2011 | Tips and Tricks, Video, Web Development, Web Programming | By: Mark VandeWettering

One year ago today, I first published a link to The Broadcaster Project, a site which had several tips on using command line tools such as ffmpeg to assemble videos. I use a similar technique to do my more recent videos: I take the raw footage from the camera and resize it, denoise it, and […]

All LEDs are not created equal…

May 17, 2011 | electronics | By: Mark VandeWettering

Of course I knew that all LEDs aren’t the same: they differ in color, size and brightness. They also differ in the forward voltage, reverse voltage and capacitance. When I simulated the Joule Thief with LTSpice, I just picked a random LED out of LTSpice’s catalog. When I simulated it, I got a waveform like […]

Update re: the HamCan.

May 17, 2011 | Amateur Radio | By: Mark VandeWettering

Dave, NM0S and designer of the HamCan, a kit that I previously assembled, but had some difficulty with nicely contacted me via email today so ask if he could be of help. I’m pretty sure that whatever the issue is, it’s my own fault, but hopefully with some patient help from Dave I can figure […]

My trip down memory lane leads me back to TOPS-10 and the PDP-10

May 17, 2011 | Computer Science | By: Mark VandeWettering

I’m going to be nostalgic for a few moments. If you are too young to have any sense of nostalgia, skip ahead to the bold text below. You were warned! A few days ago, I mentioned that I was having a bit of flashback, thinking of my first experience with time sharing computers back in […]

Toronto Mini Maker Faire

May 14, 2011 | Amateur Radio | By: Mark VandeWettering

Next weekend is our Maker Faire here in California, but there was just a Mini Maker Faire in Toronto, and it looked like there was some awesome stuff. Check out these neat video: Makers: Mini Maker Faire Toronto from Ryan Varga on Vimeo.

Inductive Spikes: Simulation and Reality

May 11, 2011 | Amateur Radio, electronics | By: Mark VandeWettering

Kindred spirits Atdiy and whisk0r over at the tymkrs blog were playing around with inductors: They demonstrated that inductors can generative large inductive spikes: in spite of the fact that there coil is charged by a relatively low voltage, when you sharply disconnect a coil from a charging voltage, it generates a large voltage spike […]

Flashback: the DEC 1091 at the University of Oregon

May 11, 2011 | Amateur Radio | By: Mark VandeWettering

In my previous post, I mentioned that I had programmed a machine that used core memory. It was the DEC 1091 we had at the University of Oregon back in the mid 1980s. I was overcome with a feeling of nostalgia, and decided to try to look up how to install TOPS-10 onto the simh […]

Magnetic core memory reborn… on an Arduino????

May 11, 2011 | Computer Science, electronics, Hacking, Hardware | By: Mark VandeWettering

I may have mentioned before, I’m kind of old. One measure of how old I am is the fact that I’ve actually programmed machines that used core memory. Real core memory. Little ferrite donuts on arrays of wires. Some time ago, I remember running across this awesome blog post from “Wayne’s Tinkering Page” which showed […]

Simulating the Joule Thief with LTSpice

May 10, 2011 | Amateur Radio, diy, electronics | By: Mark VandeWettering

I always think it is good to follow up a practical build of an electronic circuit with some simulation to try to learn some of the underlying design principles. LTSpice is a great circuit capture/simulation system which runs on Windows, but also runs pretty well under Wine. I was a bit intrigued by the behavior […]

The Joule Thief — Lighting an LED with 1.5 volts

May 9, 2011 | Amateur Radio, electronics | By: Mark VandeWettering

I was bored, but not quite up to the challenge of debugging my existing radio project, or starting a new one. I idly began winding some wire onto a FT-37-43 toroid, and then remembered that I had never constructed a “Joule Thief”, a simple little circuit that allows you to light an LED using just […]

Ugly is Better

May 9, 2011 | Amateur Radio | By: Mark VandeWettering

So, over the weekend I assembled the HamCan, and got some pretty wonky performance. I’m going to go through it all again and see if I can figure out why the receive performance is so bizarre, (loose connection? poor adjustment?) but it got me thinking that part of the issue is that typical PCB construction […]

Today’s Project: The HamCan

May 8, 2011 | Amateur Radio | By: Mark VandeWettering

I ordered a little HamCan kit about a week ago. It’s a little QRP CW transceiver produced by the Four State QRP kit. Today, I spent about an hour assembling it, and fired it up. This is just a short status report: it’s acting a bit wonky. The tone sounds pretty rough, the frequency seems […]

Astronomical Musings: What day is Pixar-Henge day?

May 6, 2011 | Astronomy | By: Mark VandeWettering

I’ve had a couple of conversations with Tom over the last couple of days, and they were curiously related. He just got back from a trip to Ireland where he visited Newgrange, a prehistoric tomb mound in County Meath. It actually predates the Great Pyramid at Giza, and predates Stonehenge by a thousand years. One […]

Word squares…

May 4, 2011 | Computer Science, My Projects, Puzzles | By: Mark VandeWettering

I like to read the Programming Praxis website. Every post challenges you to write some simple programs to boost your skill, akin to finger exercises for a musical instrument. Today’s challenge was an interesting which intrigued Charles Babbage: creating word squares. I spent about 10 minutes writing one in Python that worked rather well: here […]

A small standalone homebrew computer: FIGnition by Libby8dev

May 1, 2011 | electronics, Hardware | By: Mark VandeWettering

I’m old. I learned to program as a teenager in the 1980s. Back then, we learned to program on small microcomputers. These machines weren’t very powerful, but they had a neat feature: they were self-hosted. In recent years, a large variety of small microcontrollers have become popular. Many of these have capabilities far in excess […]