Projectile speed sensor

[Mike] built a sensor rig to measure projectile speed. The setup uses a tunnel with two sensors in it. Each consists of a laser diode on one side focused on a photodiode in the other. The two are monitored by an op amp and measured by an ATmega128 microcontroller. When the beams are broken the elapsed time between the … Read the rest

A cop in every car

[Michael] designed this display board to mimic the appearance of a police car pulling you over. It resides in the rear window of his car (facing forward) as the controller board measures the speed of the vehicle. An Arduino grabs NMEA data from a GPS module and compares it with a table of speed limits. If you are speeding, … Read the rest

PHP runtime rewritten, by Facebook?

Yes, its true. Facebook has completely rewritten the PHP runtime to make it faster and more efficient, and its completely open source. Named HipHop, its described as a source code transformer, changing PHP into optimized C++ which is then compiled using g++. Thus keeping the best aspects of PHP while taking advantage of the performance of C++. Using HipHop, the … Read the rest

Bike trainer computer: Speed, Cadence, Heartrate, Trainer temp

[Kurt] was using a bike trainer to get in shape for warmer and dryer biking months. Unfortunately it’s pretty hard to train if you don’t have reliable data concerning how hard you’re working. There’s commercial solutions for trainer computers but he’d read some rough reviews about them and decided to build his own trainer computer. He’s done a great … Read the rest

Capturing bullet speed

Sometimes it’s amazing how slow our sense of time is. We find [Maurice's] bullet capture system a great example of this. A pair of IR sensors spaced two inches apart can capture and calculate the speed of a projectile. Couple this with a user-input distance from the sensor to the target and a microcontroller can extrapolate the exact moment to … Read the rest

Beauty in Destruction

This is not a hack. In fact it’s a promotional montage for a collection of scientific equipment that few of us could likely afford. But like yesterday’s giant marionettes over Berlin, sometimes even a costly and delicately-orchestrated achievement transcends its own not-a-hack-ness, fulfilling our brains’ lust for wonderment all the same.

Kurzzeit of Germany produces ballistics measurement equipment. The … Read the rest