Quote:
Originally Posted by Eric H
Can you imagine the Flicker of light bulbs at 25 Hz?
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I've seen it. Back in the early 60's, parts of the New York City subway system used 25Hz. Their light bulbs lighting the stations did flicker. An oddity of the human eye is that the brighter the light source is, the higher the frequency you need to avoid the perception of flicker goes up. The rest of the station didn't seem to flicker as much as the bare bulbs themselves did. As the rest of the station hits your retina as a lower bightness level. Also 3 phases of electric supply would also smooth things out.
You also see this effect on 50Hz TV displays (PAL) vs 60Hz (NTSC) at higher brightness settings on CRTs.
A power transformer designed for 120V@25Hz in theory will be happy at 240V@60Hz. All the secondary voltages will be twice the rated voltages. One limitation is how good the insulation is on the secondary used to make B+.