There is also a new type of sensor... I watched the whole evolution take place on one of my neighborhood streets. This is a camera sensor and it apparently looks for some object that appears in the field of view and has a certain contrast before it changes.

On this particular street, I could never get the loop to trigger... and later the engineers told me that the loop was bad and could not be adjusted, so they replaced it with a video sensor.

Now I find that if I approach right in the center of the lane, the light triggers just moments after I get to the stop line. If I arrive in the dark and don't have lights... no trigger. If I wear dark clothing, no trigger. But with that in mind, I know how to trigger the thing and now dress and light accordingly.