Brandon's Notepad

January 26, 2015

DeLorme Tripmate GPS

Filed under: Electronics — Brandon @ 5:02 pm
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Like a lot of folks out there, I picked up an old DeLorme Tripmate GPS at a rummage sale for only a few bucks. No, I haven’t done a thing with it since then, but I’ve kept it around because one day I will have the time to play with it…really, I will. Honest.

Self Start Modification

This mod is definitely first on my list to try. When power is first applied to the unit, it enters a standby mode and must hear the word “ASTRAL” on its serial port before it will start receiving satellite data. The great news is that while it is in standby mode, it also sends the word “ASTRAL” every second; thus, the most straightforward hack seems to be to jump the two solder pads on the PCB so that it tells itself to enter receive mode.

External Power

This GPS runs on four 1.5v AA batteries. According to several sites, the battery life is not great. And if I recall correctly, there is no external power port and no off switch. The most popular mod is to add a power regulator so that the Tripmate can be powered by a wall mole, auto adapter, etc. Some of the solutions linked below are duplicates of the links for the Self Start Modification.


The Tripmate is obviously designed to connect to a computer’s DB9 comm port, which is becoming increasingly uncommon since the advent of USB. Here are some alternative insterfaces.


August 19, 2011

Easy Button Hacks

Filed under: Electronics — Brandon @ 8:57 am
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Staples office supply store chain reinforces it’s “That was easy!” slogan with giant novelty buttons that repeat it when pressed. Inside is a circuit board with a built-in momentary switch, a speaker, batteries, and metal weights. These are easily hackable.

Custom Message Buttons
Because the default one gets boring pretty quickly. (5th doc from the bottom)

Sound Mods

Garage Door Opener
This is a popular hack, because it’s linked many places.

Game Buzzer System

Musical Instrument Foot Switch

Home Automation


August 18, 2011


Filed under: Electronics — Brandon @ 8:06 pm
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Back to My Lists

Electricity is fascinating stuff, invisible to the eye but so very powerful.


Soldering Basics (PDF)


555 Timer IC (Wikipedia; see Modes)
4000 Series (Wikipedia)
4017B Decade Counter (good explanation)


Easy Button Hacks
Guitar Circuits
Talk-Over Circuit
Altoid Tin Stereo Mixer
DeLorme Tripmate GPS
DIY Knight Rider Lights (good explanation)
30 LED Projects (also includes Knight Rider)

December 31, 2009

Beowulf Clusters

Home > My Lists > Technology > Hardware > Parallel Computing > Beowulf Clusters

The Beowulf Cluster is one of the reasons I jumped onto the Linux bandwagon in the late 1990s. The idea of making good use of old computers to solve real world problems fascinated me. As computers continue to shrink in size, price, and power consumption, the reuse aspect is less appealing than before, but the concept still draws me in from time to time. I only wish I could justify the cost of building one.

General Information

A Beowulf Cluster generally refers to a collection of consumer-grade computers connected by a local network that run parallel-processing applications. The typical Beowulf Cluster runs on the Linux OS and distributes processing tasks using either Message Passing Interface (MPI) or Parallel Virtual Machine (PVM) libraries.


How To Build A Cluster

Building the cluster is half the battle (the other half is writing programs for it). Thankfully, there are a lot of how-to pages out there. Some cover just the basic steps while others provide more explanation and background information. It’s been interesting to watch them evolve over time to, in length, complexity, and style. Here is a sample:

Finally, this isn’t a how-to article, but it’s worth the read. Cluster Urban Legends: Build Your Cluster With Facts Not Fiction, written by Dr. Douglas Eadline in 2007, debunks some of the major myths and misunderstandings surround Beowulf Clusters. In short, it helps you determine if you are really building one for the right reasons.

Cluster Programming

So, you’ve built a Beowulf Cluster. Now what? Well, now You have to write programs for your cluster to solve all of the world’s complex problems. Beowulf Clusters are built for crunching numbers, not serving up web pages. That means they are used primarily in the sciences, though I can think of a few business applications that could benefit from the extra processing power (think derivatives pricing).

I have a lot more research to do in this area. Currently, I have only a link to some information about an old text book to offer. I need to add more tutorials to this list, especially in the use of MPI and PVM, and how to determine when it’s appropriate to use one over the other. Check back later or watch my Twitter feed for updates.

Real World Beowulf Clusters

Years ago, I started compiling a list of real Beowulf Clusters that had been built for various purposes. I still have the list, though some of the links are now gone or only available on the Wayback Machine Internet Archive. I was hoping to do a little write-up on each cluster on the list, but if that doesn’t pan out, then will just add the list in this section.


And of course, most scientists, engineers, and computer geeks are gifted with a great sense of humor (even if we are the only ones that understand our own jokes).

January 5, 2009

Guitar Circuits

Filed under: Electronics,How-To — Brandon @ 12:04 pm
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I just finished building a portable guitar amp as a Christmas gift for a friend. It runs on a 9v battery, fits into an Altoids tin and drives headphones so that the whole family isn’t disturbed during a midnight jam session.

Here’s the schematic I used:

For reference, here are some links for guitar-related electronics:
Wiki article on guitar effects
Awesome collection of schematics!
The good stuff is under “projects”
Cannibalized Tape Player
A Discrete FET Guitar Preamp
Active preamps, MODboards, and other parts

Some more general information:
Electronic Cookbook
Altoids headphone amp

Links to process:

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