In #nesdev, bunnyboy asked how to test the video lag of an HDTV showing an NES picture. Someone suggested rigging a photosensor to the controller port and using the NES to count the time. So I wrote an NES program that measures time-to-light in milliseconds using the photosensor in a Zapper. It works on a CRT, where I get the expected sub-15 ms depending on how low it's pointed. My cousin reported being able to get the test screens in Zap Ruder to see his 6-month-old LCD HDTV, not the position on the TV but at least the fact that it's pointed at the TV. But I can't get the Zapper to see my (older) LCD HDTV's backlight at all. Perhaps his TV's backlight somehow gets past the demodulator in the Zapper; it might be a difference between CCFL and LED backlights.
Someone else would have to rig up a different photosensor circuit that sees any light source. Ideas?
Someone else would have to rig up a different photosensor circuit that sees any light source. Ideas?