hi every one, i jsut finished my A levels and i just wan to know how can i construct my own light gate circuit. I have an I.R emmitter and a sensor but need to know how to get it workin. So if anyone out there knows how to do it, plz help me.

thanks

 

A light gate circuit? What is it?

 

well, i just know about those light gates which are available in shops for timnig purposes. I read that they work with an IR trans. and receiver. So i guessed i can try to make my own but i don't know which part has to go where.

 

hi,

pls. check in the "project forum" about infrared chronometer. i believe your problem is similar to the topic started by "congo blue"

moz

 

So a light gate is a device to measure time intervals. The timer starts when a beam of visible or infared light is broken and it stops when another similar beam is broken. In the interval between those two events the ticks of a free running timer counter are accumulated and the elapsed time is computed.

Many processors have hardware called an input capture module which is designed for precisely this purpose. In the midrange PIC series it is called the CCP or Capture Compare module. In the 8051 it is called the Programmable Counter Array or PCA.