On 2007-06-04 23:27:20 -0700, "James Sweet" said:


"John Robertson" wrote in message
news:2007060422585943658-spam@flipperscom...
Hi Folks,

I'm fixing up an old light beam activated rifle gallery and want to
convert some IR Laser diode Colt-45 style pistols to a white light LED or
possibly tiny photo-flash tube.

The targets all work on visible light and use CDS cells (are these being
banned?) as the sensors.

What I have been toying with is using a 60,000LCD(?) white LED as the
light source but I'm having trouble focusing the light so that it is no
larger than about 6 - 8 inches in diameter at twenty feet. I'm not an
expert on using lenses but the flash tube version of these use a metal
shield with a small hole - I suspect to act as a point source of light -
then the lens is about six inches away. This produces a nice bright flash
at the target distance.

My problem is I can't FIT a flash tube in the barrel of the pistol! Ths
smallest flash tubes I can find are used in disposible cameras but do not
work well as there is not much light coming out the ends - the elements
are in the way. Can't bend them into a "U" shape as they would simply
collapse once heated enough to soften the glass.

The smallest u-shaped strobe tubes I can find are just over 1/2 inch wide
and the barrel is only 1/2 in internal diameter - won't fit!

So, I'm thinking I need to find out a couple of things - first; can a high
intensity LED but over driven, repeatedly, on a very short duty cycle? And
second; how the heck do you focus the bugger to something resembling a
small - but intense - circle of light at twenty feet (6 meters)?

Ideas?

Thanks,

John :-#)#
--



What's wrong with the original setup?

Does the light have to be white? If not then how about a laser diode?
Another option would be to use a white LED to make a visible flash, but have
an IR source be the actual trigger.

CdS cells are still widely used, mostly for lighting control though, they're
a bit slow for other things.

The IR laser does not set off the CdS cell. They need a longer flash
(or shorter frequency of light) than the laser provides, plus the laser
is way too precise for my customers. This is an amusement gallery and
they do have to be able to hit the targets on average. So the beam is
around 4 - 6 inches across at twenty feet.

The reason I'm trying this is simple, I'm cheap. The new photoflash
pistols (look like toys) are almost $400US and I have ten of the Colt
style laser pistols sitting idle that look way cooler... but they do
not work with the CdS cells...

I have just found some info on Luxeon LEDs and some lens systems they
work with that gets me down to 9 degrees of dispersion... getting
closer!

John :-#)#
--
(Please post followups or tech enquires to the newsgroup) John's
Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
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