On 18 Sep, 2012, at 15:06 , John Lofgren wrote: > <snip> > I would hence believe that a 50 Hz flicker must be pretty close to the edge > of what can be perceived, so I'm having trouble believing that a flicker at > more than twice that rate would be perceptible at all by anyone. > <snip> > > Oh, but it is. A couple of years ago I bought one of the Chinese 30 LED spot > light bulbs for about $8 on ebay. I thought I'd give it a try for a > workbench light. When I plugged it in at work (60 Hz power, here) the two > guys standing behind me yelled "gaahhh" at the same time I did. The flicker > was horrendous. The earlier comment about peripheral vision also applies, > though. It's worse in the periphery than in direct view. > > The "power supply" is nothing more than a bridge rectifier, two current > limiting resistors, and a filter capacitor. The capacitor obviously wasn't > big enough, though, because it flcikered plenty.
Or could the problem have instead been that one side of the bridge wasn't working, so you were getting a 60 Hz flicker rather than 120 Hz? Having seen what I am sure was a 50 Hz flicker, I'd believe that 60 Hz might look awful but I still have some doubt about 120 Hz. Dennis Ferguson _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
