In the photo above: On the firing line with the Arduino-based chronograph for potato velocity assessment. Arduino Uno and LCD control panel in the foreground

The Chronograph project was simply intended for fun. Having built a compressed-air potato cannon some time ago, I wanted to assess how well it performed- more specifically, how fast the potatoes exited the muzzle. While there are many affordable chronographs available on Ebay and elsewhere, the potato cannon posed some special issues:

  • The potato is accompanied by a lot of gunk at the muzzle exit and most if not all chronographs would mis-read the high-velocity gunk as the intended projectile; a chronograph sensitive to only large objects was needed.
  • Aiming accuracy for a potato cannon is incredibly poor. It is therefore dubious to consider placing the chronograph at a large distance from the muzzle because you will likely hit and destroy the chronograph within just a few shots.

In the above photo: Time gate master circuit board in place, ready for attachment to the Arduino Uno

The chronograph design described here addresses these important issues as well as others. Design details including schematics are provided here plus a detailed two-part written report.

An Arduino Uno equipped with a LCD add-on display is used to arm and read back information from the time gates. As simple as the interface is, almost any microcomputer would suffice for the task.