light-sensitive tv gun

[thiaguetz]

Hi,

Anybody know the details of this old-tecnique videogame toy?

I want to build something like it, but, of course, with PIC

My doubts is about the tv frequency...

I builded a litte prototype using a phototransistor that oscillate 5v when the sensor see a white block on TV and it drops 0v when he see a black block.

BUT, i remenbered that the TV oscillate the entire screen causing a litte delay between the static color that i want to detect.

Just a detail, when i test the circuit with static source lights, it works perfectly. When i aim the sensor to a non-light object, it drops 0v (my debug led stay off), and whe i aim to a static red led light source, my debug led stay on while the sensor is detecting light.

In resume, i want to transform the oscillated white and black colors to static light sources. So, my sensor and the PIC can work only using 5v and 0v pulses.

Thanks!

 

[Someone Electro]

CRT TVs and computer monitors can display only one pixel at a time.To make an image out of it the CRT drwavs the pixels left,right,left,rifht...and evry rov of pixels is completed in goes one line down and thins conitunes until the vhole picture is drawn.This goes so fast that we see an image insted of an single lighted pixle.
Tthese guns use this.So wen its poited at the curently drawn pixle it sends an 1 if an and non lighted pixle it gives an 0.and becose the game console knows what pixle on the tv is drawn it wits for the 1 form the gun and wen it gets the 1 it checks which pixel its curently drawing.the pixel that is drawing its the pixel that your ponting the gun at