Our local high school has a drum line that provides the community with an outstanding indoor performance each year. Yes, you read that correctly. An indoor performance. As in, one million decibels of drumming in a closed auditorium. Well, it is actually a full band concert, but the drum line steals the show. It’s a blast, and I was asked to come up with some unique lighting for the drummers this year. Continue Reading
This project was one of the more enjoyable projects that I’ve worked on in a long time. Instead of taking the easy way out and displaying the current weather conditions on a web site or cell phone, this project focused on simplicity. Minimal information, displayed in a visually appealing non-screen format. This project makes use of several d’Arsonval meters and a Particle Core microcontroller to view the current weather and forecast at a glance. Continue Reading
Our first generation robotic lawn mower wasn’t the complete success that we hoped it would be. It started off simple enough, as a remote controlled lawn mower, using a hobby RC controller and some used wheelchair motors. With some simple steel framing, the lawn mower was durable, easy to drive, and worked surprisingly well for a remote controlled mower. Well, it was a little hard to steer in a straight line. That’s why I added a GPS. However, when I attempted to add the GPS and inertial guidance functionality to see if it would operate autonomously, it failed miserably. Although it would navigate to preset waypoints, it would only find one waypoint on the North side of lawn, and one waypoint on the South side. Obviously, this wouldn’t be sufficient to operate as an autonomous lawn mower. The goal here was not a random pattern, but a parallel path mowed lawn. Continue Reading
We were only about one month into the 2013 lawn mowing season when we decided that we had had enough. Mowing the lawn wasn’t fun. It’s hot, dirty, smelly work that is better left to someone, or something else. We decided right then and there that we needed to make a robotic lawn mower. One that could be controlled by remote control, or if we were adventurous enough, one that was fully autonomous.
We had only one requirement for this project. The robotic lawn mower would need to mow in a pattern similar to how a human would mow – with straight lines. A lawn mower that operated like a Roomba in a crazy, random pattern was not going to work. We planned to start with an existing lawn mower, modify it for remote control, and then eventually include an inertial guidance system and microprocessor to allow it to mow on its own. Continue Reading
Now that we have our first nixie tube clock built, it was time to step it up a little and make something a little more challenging. Nixie tubes, using a glow discharge instead of LCD or LED displays, have an old world charm to them, yet can be made to operate similar to a modern display. The plan here was to pair these tubes with a nice wooden clock case, made using the CNC machine. The end result is something that has a warm wooden feel to it, with a colorful numeric display which is both attractive and, when used with a GPS for accurate time setting, highly functional as well. Continue Reading
After constructing a solar panel and battery system to power a Raspberry Pi, I wanted to find a way to monitor how the battery and charger was performing. There are several ways to accomplish this task, usually involving a voltage sensor, a current sensor, or both.
A voltage-based sensor can be used to monitor the charge of the battery. Over a typical day, the battery voltage should rise as the solar panel charges the battery, and then discharge at night while the Raspberry Pi consumes power from the battery. A common technique for monitoring voltage is to use a voltage divider. If appropriate resistances are chosen for the voltage divider circuit, the drain on the battery from the sensor is negligable.
Another option is to use a current sensor. A current sensor placed off of one of the battery terminals will measure how much current is flowing into or out of the battery. Continue Reading
While browsing one of our favorite electronic supplier’s web sites, we found that Ladyada sells a really interesting looking clock that uses a vacuum florescent display with eight glowing digits. This clock proved to be an excellent soldering instruction project for a younger Rusty Nail Workshop helper.
The most interesting feature is the display, which is similar to those found on VCRs, old car radios, and microwave ovens. The vacuum florescent display was invented in 1967 in Japan and hundreds of millions are used annually around the world. They are different than an LCD in that they use a filament to emit electrons which are diffused by grids. The electrons strike a phosphor-coated plate and emit light, and can be manufactured to emit light in different colors. Continue Reading
For Halloween this year, my boys decided they wanted to be a Jawa from Star Wars. One of the requirements was that they have glowing eyes. Not just any glowing eyes, but orange glowing eyes. This is how I created some realistic Jawa eyes with just a few dollars of materials.
First, to get the orange glow, I purchased some high intensity orange LEDs (part number 404-1097-ND) from Digi-Key. They were only $0.71 each. I also purchased a 9-volt battery clip (part number BS12I-HD-24AWG-ND) for $0.33. To control the current going to the LEDs, I purchased a 500 ohm potentiometer (part number 3386W-501LF-ND) for $1.29. Continue Reading
Everything I had read thus far told me that I needed a circuit which supplied a constant current to the laser diode. It would have been easier if I could have just connected the laser diode to my DC power supply and adjusted the voltage, but that would have been too easy.
About six months ago, I purchased a Sharp Aquos BDHP20 Blu-Ray player to watch movies I rent via Netflix. The DVD player worked perfectly for several months, enabling me to watch all sorts of movies in high definition. Life was good.
Then one day, a disc refused to load. I figured it had a scratch, and I tried other Blu-Ray discs. None would load. I found a firmware update, and updated the firmware. No go. The player still wouldn’t read the discs. It played DVDs just fine, but not Blu-Ray discs. I eventually got frustrated enough to purchase a new Blu-Ray player, figuring I’d dissect the old player and extract the Blu-Ray laser diode. Continue Reading