Circuits motion detector light assembly 3 way proximity

[VxP]

Is it possible to create a series of circuits capable of detecting a moving object with 3 levels of proximity e.g. green light when object is 10ft. away, yellow light at 5ft., red light at approx. 1ft. away, etc?

Thanks, Dave

 

[anorlunda]

Yes. The simplest way I can think of is the photo detector method. Simply shoot a beam of light across the path, and sense when the light is interrupted by a passing object. You can have multiple beams at different distances.

Automatic doors at stores and office buildings and garage door openers use such photo detector circuits.