SpudFiles

Anybody tried making one of these, does it actually work ?

Of course.

noyce

I think that is a bit more complex than needed. You don't need the IR LEDs since ambient light is usually enough. You can use a slice of a pipe to mount the phototransitors so that ambient light can get to the detectors. Since you don't need the LEDs you don't need to use the USB port.
http://www.inpharmix.com/jps/Jims_chrono.html

it's so simple it will nearly build itself

Back when I played paintball you could BUY systems that worked exactly as described in this thread. And they were pretty cheap.

BUY stuff ? I think I'm in the wrong forum

farcticox1 wrote:BUY stuff ? I think I'm in the wrong forum

D_Hall wrote:Back when...

I don't think you can buy them anymore so you're still on the right forum.

close call, back to making stuff for nothing

If you are really cheap (raises hand) you can just use your phone (or laptop or tape recorder or ...) to record the sound of your gun firing at a piece of wood a measured distance from the barrel (watch out for the ricochet). The recording will have a strong signal when the ammo "uncorks" the barrel followed shortly thereafter by the sound of it hitting the target.

When I made mine I had all the parts lying around (including the Arduino). But starting from complete scratch would require an arduino (~$40), any laptop capable of running Arduino CC (which is any laptop made in the last 20 years capable of running debian: ~$50 - max not defined), and some IR LED's and phototransistors ($10).

Jimmy's method linked on his site is probably your best bet if you have a computer with a sound card (highly likely, includes integrated audio... sampling rates will obviously differ). Although, the software recommendations could be updated a little (*hint hint* , Audacity can do most of the things mentioned on the page at least on Debian).

If you're transitioning to Larda-level velocities, or you want something dead simple, you can build a break-wire chronograph, which is exactly what it sounds like (a wire carrying a sense current which when broken triggers either the "STOP" or "START" function of your "timer", which could also be a sound card).

mark.f wrote:Jimmy's method linked on his site is probably your best bet if you have a computer with a sound card (highly likely, includes integrated audio... sampling rates will obviously differ). Although, the software recommendations could be updated a little (*hint hint* , Audacity can do most of the things mentioned on the page at least on Debian).

Actually, the page does say:

Note Added 16 October 2007.
I no longer use SoundRecorder or AudioEdit. The best freeware program I've found for recording and displaying sound files is Audacity.

jimmy101 wrote:Actually, the page does say:

Note Added 16 October 2007.
I no longer use SoundRecorder or AudioEdit. The best freeware program I've found for recording and displaying sound files is Audacity.

My mistake, nice catch.

Has anyone here tried any of the various chrony smartphone apps? I have one called Chrono Connect but have yet to try it.

If I'm reading it right it works like a normal "microphone chronograph" which can be done without spending $3.85 to unlock the "Pro version". It's handy to have available on your phone, but as mentioned, the technique is really simple and can be done with few special "tools" (software).