The comments say the author got it wrong, essentially, and that the gun looks for a 15.7khz modulation, rather than just contrast in a certain time range. The c

The comments say the author got it wrong, essentially, and that the gun looks for a 15.7khz modulation, rather than just contrast in a certain time range. The commenter says he's used the zapper in a light-harp application and knows that the sensor cares about the modulation frequency. The linked to video (of one working on an LCD) has been hacked to work with an LCD and is not stock, per the comments on the video. Interesting!