When you press the trigger the duck on the screen turn into bright white squares for one frame or so, while the rest of the screen gets dimmed. If you hit a duck (point the gun directly at it), a sensor picks up the light and it counts as a successful hit. You can cheat by basically pointing the gun at a lamp while shooting :p
I don't know why it wouldn't work with new TVs, maybe it has something to do with quicker refresh rates? That shouldn't be it because the frame output from the NES doesn't change.
It's because for the zapper and LCD tv looks black, it's probably because LCD TV can't turn black for except just one area so everything turns to the same color and it doesn't work.
I don't know why it wouldn't work with new TVs, maybe it has something to do with quicker refresh rates? That shouldn't be it because the frame output from the NES doesn't change.