The Bt878 chipset is fairly common on TV tuner cards. The chip has a built in analog to digital converter with a sample rate of 119kHz to 448kHz, well above the standard audio rate of 44kHz. The hardware has to be hacked a little to inject your signal since the chip is usually receiving audio from the turner. With some driver hacking this chip can be pushed to 896000 samples per second. Recent developments make things even easier with ALSA support.
[thanks rockarolla]
Max and Phildog hit the shooting range this weekend to see if they could accurately measure bullet speed using Audacity. Using Audacity to examine the wave form they can determine the time between the shot being fired and striking the target. This time needs to be adjusted based on the known distance to the target. They’ve got data from quite a few different guns, but this is just a test run and they’re still improving their technique.
This coil launcher is based on a disposable camera flash system. It uses the charging system from one camera plus the the flash capacitors from four cameras. The coil is 200 turns in 10 layers wrapped around a glass tube with a 3mm inside diameter. The projectile is a 2.5mm diameter nail. It certainly isn’t as high powered as some of the systems we’ve featured, but firing at 20-25m/s it can still be dangerous.
[thanks phuzzy3d]
[Aj] found this great article for building a really cheap microscope. The goal of the project is to construct a compound microscope that is superior to the cheap toy/children’s microscopes. Besides standard construction materials it uses the lenses from four disposable cameras. The article also covers a lot of possible improvements to the ‘scope: focus control, fine focus control, condensers, different eyepieces.
We’ve hit on a few EM projectile systems recently, so [Jason Rollette] thought it would be a good time to cover his railgun. I couldn’t agree more. Jason has been keeping his Railgun Blog up-to-date from nearly day one. Right now he is assembling a larger capacitor bank to power the gun. The PVC piping you see in the picture is part of the injection rig; If the projectile is stationary when the gun is fired it would get welded to the rails (if not worse). Check out Jason’s Railgun Blog for details on his project plus a lot of informative links.
Polyphasic sleep is a method for increasing the amount of time you spend awake during the day. By sleeping only twenty to thirty minutes every four hours you can stay awake longer. The short time you do spend sleeping the body is in REM sleep, which is the most restful phase. This technique has been used by many famous inventors. I first stumbled across this idea in an article on Kuro5hin. This mode of life can be very difficult to adjust to. In the first few days you probably won’t be asleep when you are trying to. You must strictly follow the sleep schedule. Skipping a nap will probably cause a major crash. With limited sleep a nutritious diet will become very important. Hack-A-Day reader [Nick Busey] is a week into his second attempt at switching to the Uberman cycle and is blogging his progress. If I were to attempt this I would probably get something like the Earlarm to help out. Of course if you’d rather sleep more you’re probably better off with the 28 hour day.
The P.E.S.T. is a “centrifugal” launcher using a rotor powered by a DC motor to accelerate plastic BBs. It has a 50 round magazine and 3 fire modes: semi-auto, 3 round burst, and full-auto. Fire is not instantaneous because it takes 0.75 seconds for the rotor to spin up. If you follow this “read” link you’ll find a detailed description of the device. Photos can be found here.
