Laser Beams and 555’s

March 2, 2011 by

This page serves as my contest entry for the 555 timer design contest.

I have created a laser trip wire that actuates a camera. An ambient light sensor by Vishay ,  the TEMT6000 [datasheet] from Sparkfun Electronics, acts as  an NPN transistor attached to a 555 in BiStable mode. The output is sent to a logic inverter for quick visual status, then off to another 555 in Monostable configuration. The output from that 555 can be used to actuate any number of devices (Electric squirt gun, Sirens, Nerf guns, etc.), but in this example I have my camera set up in continious fire mode, as the output stayes on for several seconds. This could be used for catching a burgler (who probably wants to steal my camera), or more usefull items such as taking pictures at the end of a race.

I have a green laser for visuals, but it is probably possible to use alternate frequencys or light that are less visible to the human eye.


laser ——-Light sensor(npn) ~555 bistable> inverter logic chips and Status leds> 555 monostable >transistor (npn)-relay >camera trigger > CLICK!

The block diagram:

The schematic:

Video of my submission below: