plan to measure the muzzle exit time from barrel

hi

i am involed in a project on finding out ballistic time of muzzle. ballistic time means time taken from trigger the carrtrige to exit of muzzle from barrel. i have made arrangement to get a rising pulse from triggering point using a slotted optocoupler. i am using arduino uno. my code is to start the timer1 when interupt on pin2(trigger) and stop the timer on interrupt on pin3(muzzule exit). The software is working fine giving accurate result(compared from oscilloscope).

my problem is many times i am not getting the muzzle exit signal . to get the muzzle exit signal i have used laser transmitter and receiver .and when the muzzle passed through it i get a pulsae. the receiver circuit is a photodiode comparator using op07 ic.i dout the responce time of comparator.

the muzzle interuption time is about 70 microsecond. and the toatal time(ballistic time) to be measure is 6000 microsecond.

pl suggest me a suitable conditioning circuit to detect such a high speed muzzle .

you don't 'trigger' a cartridge. the projectile exits the muzzle. the muzzle doesn't go in or out of anything, six seconds seems like a very long time to wait for the projectile to exit the muzzle,,,, how long is that barrel anyway?

I would be very interested in this project!

I work with Airsoft guns, and for the gun to be allowed into a competition it needs to have its feet per second of projectile recorded.... Normally airsoft guns are under 700 fps, anything over they are considered dangerous to use and not classified as airsoft. Well people like to modify their weapons and still use them in competitions, possibly hurting others. The current devices that are used for measuring this are very costly, and even though their price is high they fluctuate with temperature and in some cases humidity.

Thanks, Rick

123Splat: you don't 'trigger' a cartridge. the projectile exits the muzzle. the muzzle doesn't go in or out of anything, six seconds seems like a very long time to wait for the projectile to exit the muzzle,,,, how long is that barrel anyway?

sorry for my english. the projectile exit . trigeered to primer . it is not 6 second. the time will be in the range of 6000 microsecond.

The current devices that are used for measuring this are very costly, and even though their price is high they fluctuate with temperature and in some cases humidity.

That is natures warning sign that such devices are not easy or cheap to construct. You might look at the radar speed gun kits to see if they could be modified for higher velocity measurements. High speed photography projects may have quick reaction/timing info.

Hi, What is yor projectile? Is it 100% opaque to your laser? You could look for a higher slew rate comparator.

Have you used your CRO to look at the muzzle projectile pulse?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Tom.... :)

TomGeorge: Hi, What is yor projectile? Is it 100% opaque to your laser? You could look for a higher slew rate comparator.

Have you used your CRO to look at the muzzle projectile pulse?

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Tom.... :)

It is 100 percent opaque to laser. Muzzle projectile pulse is about 70 microsecond. I have seen in cro.

Have you observed the muzzle projectile pulse on the oscilloscope when it fails to stop the timer? That is, can we rule out one or the other of "the pulse is bad" versus "the Arduino is missing an apparently good pulse"?

If the pulse is corrupted, perhaps there is a problem with ambient light and/or muzzle flash illuminating the photo diode.

You might consider firing a special paint ball (do you use a standardized paint ball for the measurement, to prevent cheating?) down a tube which can trigger a hall effect transistor or optical detector.

gumbie02151: I would be very interested in this project!

The current devices that are used for measuring this are very costly, and even though their price is high they fluctuate with temperature and in some cases humidity.

Thanks, Rick

What is high cost ?

Mine cost about 30 and thats for a rifle.

amubgr: Muzzle projectile pulse is about 70 microsecond.

That would imply a muzzle velocity of 14 Ms if i have my sums right.

What is the gun you are using and give a circuit diagram of your detection circuit.

amubgr: pl suggest me a suitable conditioning circuit to detect such a high speed muzzle .

I have never seen a ballistic measurment system with less than sub microsecond precision.

Most use led not laser.

Laser chronographs exist but are very costly, mainly because they are difficult to engineer. The electronics are trivial.

As zoomkat said , there is a reason for that.