Fluorescent Bulb Flicker

They don't extinguish. They may dim, but due to persistance of vision (even 16 fps is ok for movies, right?) you can't see it. You need to use Schlieren photography to see it.

Even Rudolph's poo welcome...all religions welcome in India

I don't know the answer but I thought this is a good question. In places where rotating machines like lathes are used I think some strip lamps have to run from different phases of the three phase supply in order to prevent a strobe effect causing a lathe to appear stationary or slow running. Also I think that different areas of the eye have different ability to perceive flicker. The peripheral vision being more able to see it if I recall right. Also there are complex questions about what areas of vision are unconscious. It sounds odd but some of our perception and processing of perceptual input is done unconsciously. I suspect that fast flicker falls into this category. David in UK.

dave; there are not any 3 phase AC lights, there is a capacitor in the ballast of a 2 lamp

to shift the voltage to the second lamp perry

Thankyou Perry. I thought I had read something somewhere about different phases being used but I was wrong. david

Perry, My memory might have been working after all! I looked and found a few sites that talk about using different phases of a three phase supply to prevent flicker. One is http://personal.cityu.edu.hk/~bsapplec/lighting1.htm which says: "6.6 Flicker and Stroboscopic Effects The light output of all lamps on an a.c. supply has an inherent cyclic oscillation which is small for filament lamps and more marked for discharge lamps including fluorescent lamps. The oscillation may cause flicker, or stroboscopic effects, or both. The stroboscopic effect is an illusion which makes a moving object appear as stationary, or to be moving in a different manner from that in which it is really moving. Flicker and stroboscopic effect is reduced by: (i) shielding the electrodes or screening the ends of fluorescent tubes or using a special circuit, (ii) mixing tungsten lamps with discharge circuit, and (iii) dividing lamps across three phases."

Off the subject, but kinda neat. You can take a hand-held RPM reader and point at a flourescent bulb and actually count the cycles.

With small neon lights, LEDs, and vacuum fluorescent digital displays, the lights all extinguish below their threshold voltages. If you look at such objects in the dark and saccade your eyes, you can see the strobe effect.