This simple circuit times a light source. When you illuminate the photodiode, Q² creates a pulse. When you remove the illumination, Q₁ creates a pulse

Authors	Ralf Kelz
Main Document	Article «Hack into a stopwatch to make a phototimer»
Description	Figure 3
File Format / Size	PDF / 12 Kb
Document Language	English

Slices

This simple circuit times a light source. When you illuminate the photodiode, Q2 creates a pulse. When you remove the illumination, Q1 creates a pulse