How Does a Chrono Work

[Baz JJ]

Does anybody know how a chrono actually measures the speed of a BB passing through it ?

[Zak Da Mack]

I believe it uses some clever maths by measuring the time between the entry and exit of the BB and it then works out the FPS from that

[Suzuki Yamamoto]

This should explain it for you

[jcheeseright]

Not particularly clever maths, speed = distance/time.

[TacMaster]

Just GCSE physics level maths, as cheese said

[Unrustle_Thine_Jimmies]

Tiny fairies inside get the speed of the BB with pencils and paper and then put it on a screen.

[M_P]

Just GCSE physics level maths, as cheese said

Pre-gcse level. I remember doing the speed equation among others in like year 7.

[TacMaster]

They've changed the syllabus since then, science isn't split down into physics/biology/chemistry for the lower years, and the speed equations etc are part of P2 now.

[Baz JJ]

How does it detect the passing of the BB to start and stop the calculation ?

[Mack]

Not 100% sure but think there is two lazer beams, one at each end to detect the bb passing

[Zak Da Mack]

If you're looking to make your own chrono, I believe there is a thread on here that shows how to make one out of in-ear headphones and tin foil.

 

EDIT: found the link. http://www.airsoftsniperforum.com/32-general-sniper-talk/4264-how-make-homemade-chronograph.html

[david0512]

As others have said, the maths is not really that complicated. Speed = Distance/Time Two laser beams in the chronograph record when the bb passes through them. The time between the first and the second beams being crossed can then be worked out. The time is scaled up so that it = 1 second. The distance is scaled up by the same amount. This distance is the feet/second speed.

[Ian_Gere]

I'm 99% certain that no lasers are involved. I've certainly never seen any holes through which a laser could shine, nor any for receivers to detect when/if the laser is interrupted (bear in mind that when lasers are randomly wandering around in films, and thieves must play mime-twister to get past them, that is complete bollocks - a laser detection system needs an emitter and receiver, so either the receiver must detect a beam steadily shining on it, or the receiver system must be sophisticated enough that it can detect a predetermined degree of reflected laser light from a preprogrammed 'random' beam sweep, in which case Ms. Zeta Jones could be as bendy as Blu Tac but her presence in the room would cause disruption in the reflection pattern whether she interrupted a beam or not).

 

As far as I know it's a mini radar.