i went to a shop to search for some sort of a distance mesuring sensor(for collision detection &prediction) the guy showed me a long rod-like device(had metal covering) i noticed that it had 2 leds in the front[and , as far as i remember, it had 4 wires coming out of it ] it was priced at about $…

Proximity Sensors -all about them

system January 13, 2013, 5:44pm 6

it was around 20 $

is it worth it?