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ArcticMyst Security by Avery

Athlete Photogate

Joined
Jun 29, 2012
Messages
4
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Hi guys I need some wisdom from some laser masters :) if something like this has already been posted or this is in the wrong section I apologize. I am an engineering student and an athletic trainer I am building a photogate lap timer for timing sprinting drills I mounted some radio shack project enclosures on top of mini camera pods. One containing a cheap 15$ laser I got from office max that I stripped and mounted a toggle switch and battery to and the other containing a photocell. The photocell is attached to a circuit that trips a lap timer when no light is received. The cheap laser wasn't that good to begin with and when I soldered a ground to the shell of the laser it distorted its beam diverging it badly so my photogate only works at a range of about 8" max and I need them to work at least at 2-4'. Now that I have been able to test my circuit and know it works I want to use a decent laser laser module that comes with its own connections. I don't think I want to go pricier than 30-40$ if I can keep from it. It would also run fine off of a 9v batter preferably. I want the photogate to function reliably in bright light conditions. Any help my project would be greatly appreciated I can share some pictures of it if you are interested when I get home from work.
 





JLSE

1
Joined
Dec 13, 2007
Messages
3,580
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Id go with a couple of PHR803t diodes (405nm) simply because they are the lowest
diverging vs cost. An LM317 driver set to 50mA or less would work fine.

If you want to be safe, I would keep them down to 5mW or less. If interested
I can setup 2 modules for you, and test at what current will give you 5mW.

Anything higher, and you have to be 100% sure that there is no way it could hit
somebodies eyes.

PM me if interested.. I can also make a self contained driver mounted into the
rear aixiz cap, all you need to do is supply the 9v...
 




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