Testing Distance Sensors

I’m working on a project involving the need to precisely move a tool based on the measured distance to an object. Okay, yeah, it’s a CNC mill. Anyway, I’d heard of time of fight sensors and decided to get one to test out, but also to be thorough I wanted to include other distance sensors as well: a Sharp digital distance sensor as well as a more sophisticated proximity/light sensor. I plugged them all into a breadboard and ran them through their paces, using a frame built from aluminum beams as a way of holding the target materials at a specific height.

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Getting Started with Blinking Lights on Old Iron

If you ever go to a computer history museum, you’ll be struck by how bland most modern computers look. Prior to 1980 computers had lights and switches, and sometimes dials and meters. Some had switchboard-like wiring panels and some even had oscilloscope-like displays. There’s something about a machine with all those switches and lights and displays that gets your hacker juices flowing. Have you ever wanted to get started in retrocomputing? Is it difficult? Do you need a lot of money? That depends on what your goals are.

There are at least three ways you can go about participating in retrocomputing: You can pony up the money to buy actual antique computers, you can build or buy old computers recreated with anywhere from zero to one hundred percent of period-authentic components, or you can experiment with emulators that run on a modern computer. As a hybrid of the second and third option there are also emulations in FPGAs.

You can see that the first option can be very expensive and you will probably have to develop a lot of repair and restoration skills. Watching [Mattis Lind] twiddle the bits on an actual PDP-8 in the clip above is great, but you’ll need to work up to it. The two techniques which get you going without the original hardware don’t have to break the bank or even cost anything presuming you already have a PC.

Although some sneer at emulation, for some machines it is almost the only way to go. You couldn’t buy the original EDSAC, for example. It is also a good way to get started without a lot of expense or risk. But regardless of how you do it, there’s one thing in common: you have to know how to operate the thing.

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Hack Your Memory

Imagine a fire hydrant being lifted high into the air by a large helium balloon. It goes higher and higher, but suddenly gas starts to leak out of the nozzle, which makes it sound like it’s trying to talk… but with a distinct lisp. A colorful bumblebee then lands on the balloon, licks it, and says “really yum!”  Then the bee takes out its stinger and bores on to the balloon. It pops, causing the fire hydrant to come crashing down. It smashes into a military jeep causing a massive explosion… as if it had been destroyed by a car bomb. Fortunately, the owner of the jeep, a general, was out on his rowing boat at the time. He likes to row his boat at night, and is known as the “night-rowing general” around the base. He was rowing with a bit more exertion than usual, and had to don an oxygen mask to help him breath. But the mask was full of fluoride, which turned his teeth bright neon colors.

You’re probably wondering what the hell you just read. Maybe you’re thinking the author had a stroke. Has the site been hacked? Maybe it’s a prank? What if I told you that you’ve just memorized the first 10 elements of the periodic table.

The Night-Rowing-General via Memorize Academy
  • Fire hydrant – Hydrogen
  • Helium balloon – Helium
  • Lisp – Lithium
  • Bee says “really yum” – Beryllium
  • Bee “Bores on” – Boron
  • Car bomb – Carbon
  • The night-rowing-general – Nitrogen
  • Oxygen mask – Oxygen
  • Fluoride – Florine
  • Neon teeth – Neon

Much of your memory is stored in the form of associations. Encoding things you need to remember into a silly story takes advantage of this fact. The memory of a ‘night-rowing-general’ is already in your head. You can see him in the theater of your mind… rowing his boat under a black sky… the silver stars on his green hat reflecting the moonlight. Associating this visual representation of the night-rowing-general with the term ‘Nitrogen’ is very easy for your brain to do.

You’re probably already familiar with this type of learning. Does “Bad Boys Run Over Yellow Gardenias Behind Victory Garden Walls” ring a bell?  It’s nothing new. In fact, storing memories in the form of mental images was the preferred memorization method of the scholars in ancient times. Today, it has allowed people to perform staggering feats of memorization. Want to know how [Akira Haraguchi] was able to memorize 111,700 digits of Pi?

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Pogo Pin Serial Adapter Thing

A few weeks ago, I was working on a small project of mine, and I faced a rather large problem. I had to program nearly five hundred badges in a week. I needed a small programming adapter that would allow me to stab a few pads on a badge with six pogo pins, press a button, and move onto the next badge.

While not true for all things in life, sometimes you need to trade quality for expediency. This is how I built a terrible but completely functional USB to serial adapter to program hundreds of badges in just a few hours.

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How to Do Beautiful Enclosures with Custom Fiberglass

There are times when I feel the need to really make a mess. When I think of making messes with a degree of permanency, I think of fiberglass. I also really like the smell, reminds me of a simpler time in 8th grade shop class. But the whole process, including the mess, is worth it for the amazing shapes you can produce for speaker pods and custom enclosures.

Utilizing fiberglass for something like a custom speaker pod for a car is not difficult, but it does tend to be tedious when it comes to the finishing stages. If you have ever done bodywork on a car you know what kind of mess and effort I am talking about. In the video below, I make a simple speaker pod meant for mounting a speaker to the surface of something like a car door.

You can also use a combination of wood and fiberglass to make subwoofer cabinets that are molded to the area around them. You can even replace your entire door panel with a slick custom shaped one with built in speakers  if you’re feeling adventuresome.

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Linux Fu: Better Bash Scripting

It is easy to dismiss bash — the typical Linux shell program — as just a command prompt that allows scripting. Bash, however, is a full-blown programming language. I wouldn’t presume to tell you that it is as fast as a compiled C program, but that’s not why it exists. While a lot of people use shell scripts as an analog to a batch file in MSDOS, it can do so much more than that. Contrary to what you might think after a casual glance, it is entirely possible to write scripts that are reliable and robust enough to use in many embedded systems on a Raspberry Pi or similar computer.

I say that because sometimes bash gets a bad reputation. For one thing, it emphasizes ease-of-use. So while it has features that can promote making a robust script, you have to know to turn those features on. Another issue is that a lot of the functionality you’ll use in writing a bash script doesn’t come from bash, it comes from Linux commands (or whatever environment you are using; I’m going to assume some Linux distribution). If those programs do bad things, that isn’t a problem specific to bash.

One other limiting issue to bash is that many people (and I’m one of them) tend to write scripts using constructs that are compatible with older shells. Often times bash can do things better or neater, but we still use the older ways. For example:

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Fabricate Your Own Tabletop Gaming Props

Delve into the mysterious world of tabletop roleplaying games. Warhammer Fantasy Roleplay, Shadowrun, Pathfinder, Ars Magica, Vampire, whatever gets your dice rollin’ — metaphorically in the case of a diceless system. This might very well be your daddy’s D&D. If you’re not a gamer, you’re certainly familiar with the concept. People sit around a table pretending to have an epic adventure, often adding a random element with the help of dice. A map is often displayed on the table, sized for figures that show the various heroes and villains.

As a person with access to a variety of CNC machines I find myself wanting to create things to make gameplay more fun. I want to build a scale castle and have a siege. I want to conduct a ship-to-ship battle with wooden ships built to scale. But I also think smaller. What is something I could make that would help us every day? Say, a box for dice. Not every project needs to be the dragon’s lair.

It turns out a lot of other folks have been thinking about the same thing.

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