This project is a really simple accelerometer based altimeter. The assembled board only weighs 10grams; the power supply is an additional 6grams. The data collection is done by a Basic Stamp II. It records 1 second before and 11 seconds after it detects the initial launch thrust. On their first launch they got some legitimate looking data (it would have been nice if they had an inclinometer to compare it to). The second launch resulted in a catastrophic engine failure on the pad. It’s a shame they couldn’t do more testing, but at least they’ve got video. Schematics and source code natch.

The photo above is from a recent BoingBoing post on high power rocketry.

As with most precision equipment, microgram scales are usually very expensive. The close tolerance machining of sapphire pivots and computer control add to the cost. Not all of those components are necessary though. This article from Scientific American demonstrates how to build a simple microgram balance using a salvaged galvanometer. Once calibrated, the output voltage will have a direct linear relationship to the weight. There is a more recent version of this project that uses a microcontroller to overcome static friction and auto center.

Continue reading “Microgram Electrobalance” →

With Halloween only a month away you’ll want to start rounding up materials to build something like this now. Nate took the time to make this project look right. He enlarged a photo to make sure the scale was correct for the claws. The claws are mounted securely to a drawer slider Taxi Driver style. It looks like a lot of work went into the uniform as well. You’ll get the gist of it from the first few pictures the rest are just excessive glamor shots. I’ll admit that I put a lot of effort into my Halloween costumes once I got to college, but I usually fell down way to much to be wearing something like this.

[thanks fstat]

This generator is built from an old alternator and a 2-stroke gas engine. The site has some suggestions on component mounting and properly sizing the drive pulley. The importance of getting an alternator with a built in voltage regulator is also covered. You could use this to charge a race car battery between rounds or add a power inverter to power AC items. Of course you could build a gas powered blender instead.

[thanks Howard and jon]

Continue reading “Build Your Own Generator” →

The Telecrapper 2000 is designed to intercept telemarketer calls. It checks the caller ID when a call comes in and picks up if the ID is “out-of-area”, “unavailable”, or “private”. A script then begins playing a series of WAV files. A new file is played when the script detects silence indicating the marketer has finished speaking. The entire conversation is recorded for later amusement.

[thanks h-tech]

Continue reading “Telecrapper 2000” →

[Phil Pemberton] has been building quite a few battery packs over the last year and decided he needed a better method than soldering. Soldering can often damage the end caps and cell seals. He decided to build a simple capacitance-discharge resistance welder to assemble the packs more efficiently. It doesn’t take many parts, but you’ll have to do some tuning to get it to work correctly.

Continue reading “Homebrew Battery Tab Welder” →

[Ben Hou] had originally sent in Godfried-Willem Raes’s automated sousaphone project, but digging around the site reveals a ton of other instruments (seriously, autosaw!). All of them are wired to accept MIDI input and there are schematics of the microcontrollers on almost every project. Quite a few mp3s are available too. Watch out for the unexplained pr0n