Chronograph ???

hammerheadpc said:

How about this?
I use my laptop computer and a microphone.
The mic pics up the sound of the bow firing AND the impact of the arrow, 18M (20 yds) away.
I use audio recording software (Audacity) than can spectrum analyze the sound and has markers that i place on the fire and impact events and measure extremely accurately the time the arrow took to go the distance (down to nanoseconds).
It's a simple v=d/t calculation to come up with the arrow's AVERAGE velocity.

This will be somewhat less than peak velocity as measured by a chrono, but in testing i've seen that it is actually within 1 fps of chrono readings, since indoors and 20 yards doesn't slow the arrow down much.

And it could be argued that the average velocity is more useful for K.E. purposes and how well your arrow delivery system maintains it's energy down range. Sort of like comparing BHP at the crank of an engine, to rear-wheel hp.

Works really well and is as portable as my laptop.

Yes. I am a total geek.

:wink:

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Bugle 'em said:

easton has a nice chrono

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headofahessian said:

we use the beta at work, no problems!

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Tallcatt said:

I have sold two Archery Chronos by Shooting Chrony right here in the AT classifieds since this thread started yesterday. If you need one give me a shout.

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gshock300 said:

i have a shooting chrony and it works very well. Ive shot it next to another shooting chrony, a prochrono and a gehler and they were all within 3fps of each other.
the shooting chrony's and the prochrono both use an infra red receiver to detect IR shadow as the projectile or arrow passes over. the particular IR they use has a diode which is centered around 850nm in the IR spectrum.
you can use a normal incandescant bulb directly over both sensors... but not just one bulb shining down over the two because the angle of light hitting the two sensors from one source will give you a fast reading.
the light sources must be directly over the two sensors.
that is the reason fluro lighting will not work. they do not emit enough IR.

instead of using standard incandesant bulbs, you can also you Leds. Red or orange will emit enough for the detectors to work. just standard 5mm Leds, you do not need ultra high output leds. both these color leds emit enough IR for the detectors to work.
Better still is to actually use IR leds. they are a fair bit more expensive then plain red or orange leds but they will have alot more output at the correct light range
I just used two strips of 3mm by 20mm aluminium about 45cm long and bent it to an eliptical shape to follow the shape of the plastic diffusers that come with chronographs and drilled 5mm holes to mount the leds in them.. space them about 12mm center to center. I had 21 per end of the crhono. three sets of 7 and you feed 9 volts into each seven leds in series so you get a voltage drop of around 1.3 volts per led.
you dont need a high current supply. just a 9volt 500mA plug pack will do it for both spans of leds.
it works really well and gives me the same reading i would get in the sunlight.
the most important thing is to make sure that all the leds are roughly pointing towards each sensor. standard leds usually have a difraction angle of around 20degrees so thats plenty of leeway. if you spread them at 12mm center to center on each span.. you should cover most of the aluminium bar from one chrono verticle rod to the other rod.
i dont have any pics to post it up but ill try to take some when i have time. its actually quite simple.

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arkansasbowman said:

Most will need a light kit. You might get away if you have good lighting but you cannot use Florescent lights. They will throw off your readings.

I know PACT makes an IR system that does not need a light kit. You will pay about $60.00 more compared to the Chrony's or $25.00 more than the Pro Comp. models with light kits.

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jing1117 said:

4yggfgfbghgh gnggh gdgf dvfgfbbvbm. tuththuyipu`rfdg vfvcv

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hammerheadpc said:

How about this?
I use my laptop computer and a microphone.
The mic pics up the sound of the bow firing AND the impact of the arrow, 18M (20 yds) away.
I use audio recording software (Audacity) than can spectrum analyze the sound and has markers that i place on the fire and impact events and measure extremely accurately the time the arrow took to go the distance (down to nanoseconds).
It's a simple v=d/t calculation to come up with the arrow's AVERAGE velocity.

This will be somewhat less than peak velocity as measured by a chrono, but in testing i've seen that it is actually within 1 fps of chrono readings, since indoors and 20 yards doesn't slow the arrow down much.

And it could be argued that the average velocity is more useful for K.E. purposes and how well your arrow delivery system maintains it's energy down range. Sort of like comparing BHP at the crank of an engine, to rear-wheel hp.

Works really well and is as portable as my laptop.

Yes. I am a total geek.

:wink:

Click to expand...

gshock300 said:

instead of using standard incandesant bulbs, you can also you Leds. Red or orange will emit enough for the detectors to work. just standard 5mm Leds, you do not need ultra high output leds. both these color leds emit enough IR for the detectors to work.
Better still is to actually use IR leds. they are a fair bit more expensive then plain red or orange leds but they will have alot more output at the correct light range
I just used two strips of 3mm by 20mm aluminium about 45cm long and bent it to an eliptical shape to follow the shape of the plastic diffusers that come with chronographs and drilled 5mm holes to mount the leds in them.. space them about 12mm center to center. I had 21 per end of the crhono. three sets of 7 and you feed 9 volts into each seven leds in series so you get a voltage drop of around 1.3 volts per led.
you dont need a high current supply. just a 9volt 500mA plug pack will do it for both spans of leds.
it works really well and gives me the same reading i would get in the sunlight.
the most important thing is to make sure that all the leds are roughly pointing towards each sensor. standard leds usually have a difraction angle of around 20degrees so thats plenty of leeway. if you spread them at 12mm center to center on each span.. you should cover most of the aluminium bar from one chrono verticle rod to the other rod.
i dont have any pics to post it up but ill try to take some when i have time. its actually quite simple.

Click to expand...

Zappem said:

That sounds like it would be a sweet set up. When you take some pics, psot them up please so I can get an idea. Might want to try it.

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jing1117 said:

4yggfgfbghgh gnggh gdgf dvfgfbbvbm. tuththuyipu`rfdg vfvcv

Click to expand...

gshock300 said:

Here are a couple of pics of my chrono led lights.

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arkansasbowman said:

See I told you so :wink:

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