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&#x27;s used the zapper in a light-harp application and knows that the sensor cares about the modulation frequency.<p>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.<p>Interesting!