Hey,
I got various arduinos (mega, Uno etc) and I was wondering what parts I should use to make archery arrow chronograph.
I have read that people use on painballs IR-led etc. combination but it seems like its not very accurate and its not viable for measure arrows.
is there possible to make radar like device, example using microwave doppler
http://www.ebay.com/itm/Microwave-Doppler-Wireless-X-Band-Radar-Motion-Detector-Sensor-Module-Fr-Arduino-/300865404193
I would like to make it accurate as possible so list of parts (yes im beginner and my mind is blank) would help me get started.
basically it just needs two switches start and end right?
when arrow hits START sensor it starts to count hown long it takes to reach END sensor and since you program the distance, it counts the speed for you.
any links for working chronograp builds with arduino would help lot too 
Could this be used to determine speed of arrow?
projectile sensor 2 from camera axe project
http://www.glacialwanderer.com/hobbyrobotics/?p=446
Yes. To help in your search, it is called a "photogate". (That sensor is actually a pair of photogates.)
What timing accuracy do you need?
Distance between points of measurment?
What is the environment...indoors/outdoors/sunshine and is it a controlled environment?
How can you ensure the arrow passes thru a narrow set of points?
AnalysIR:
What timing accuracy do you need?
Distance between points of measurment?
What is the environment...indoors/outdoors/sunshine and is it a controlled environment?
How can you ensure the arrow passes thru a narrow set of points?
I would like the accuracy of arrow speed to me +/-2fps
Distance points I can make whatever would be best, around 30cm I think would be suitable like on retail models.
Enviroment outdoors/sunshine might be involved.
i dont know how to ensure that but I looked at chrony and I guess it has multiple leds so you just have to hit between its spots.
I know im im really beginner but I dont have any clue what sensors I should use on stuff like that.
Is it possible to build "curtain" from leds when its cut, it starts to calc how long it takes to until the second "curtain" is triggered?
accuracy is the key here. I would it really like to be around 2fps +/- if possible,
Could i make IR curtain with 4 ir leds on top and 4 receivers below and when it hits curtain, it triggers event?
If you could put some silver (or reflective) sticky tape round the shaft, you should be able to get started with a very simple reflective setup. Might be a good place to start and then evolve to a better solution based on experience.
Also consider a setup where the LEDs/receiver are facing horizontal and aay from the Sun vs up towards the sky. This way you could have multiple channels to capture different trajectories.
+/-2fps....seems to be a higher spec than the Chrony class devices. You would need to make the calculations based on the max arrow speed vs the clock on the Arduino Model or alternative of choice.