beam break to stop a display clock (this is a track and field application)?

DAVID COOKE

Can I use the basic stamp to construct a beam break to stop a display clock (this is a track and field application)?
I was thinking of a transmitter receiver type ?IR ?laser
the gap between transmitter and receiver would be 10 metres
perhaps there are schematics already published and readily available

thanks
david cooke

Post Edited By Moderator (Chris Savage (Parallax)) : 6/2/2008 4:44:37 PM GMT

Unsoundcode

The TSL230R can be used as a beam/laser·detector at this link http://www.parallax.com/Store/Components/IntegratedCircuits/SensorChips/tabid/618/CategoryID/83/List/0/SortField/0/Level/a/ProductID/88/Default.aspx

Jeff T.

Phil Pilgrim (PhiPi)

Whatever optical means you use needs to be sun- and water-proof if used outdoors. This will entail focussing lenses on both the light source and the detector to ensure that light from a stray angle doesn't prevent detecting a break in the beam. It would also be a good idea to modulate the beam as a further precaution against misfires. Banner Engineering makes "opposed mode" photoeyes that, when paired with the recommended emitter, should satisfy these requirements. I would hesitate to use anything less robust in an application like this. Snorkels on both units will help even more with collimation and to keep water droplets off the optics.

-Phil

Post Edited (Phil Pilgrim (PhiPi)) : 5/31/2008 7:35:06 PM GMT

erco

I've made photo-finish lines this way, shining a laser aross a finish line so the first break in the beam triggers a digicam pic. Very reliable and simple to build. Per PhiPi, LONG snorkels are necessary to filter out sunlight, and paint everything including inside the snorkel tubes with multiple coats of ultra flat black paint. A laser can be used at any range, 30 meters is no problem, but aligning the laser and keeping it aligned will be a challenge unless·you build it into a permanent structure, like on a concrete base. You need a rock-steady base on both sides (laser with adjustment screws on one side, phototransistor on the other).· Phototransistor hookup as previously shown at··http://forums.parallax.com/attachment.php?attachmentid=52981 (but you don't need the IR LED).

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·"If you build it, they will come."

DAVID COOKE

thanks to all respondents

david cooke