[GreenKeys] Secret DC Basement in NYC - Great History

[Doug Alderdice]

I don't have a video but can maybe describe it.  It's strange, because 
at least for me when I look directly at an incandescent lamp operating 
on 25 Hz I don't see the flicker, it's something I am more aware of in 
my peripheral vision.  I find it is a little disconcerting at first, but 
then after a while I don't notice it so much.

It can probably be compared to viewing a movie shown with actual film in 
a projector.  Movie frame rates are anywhere from 16 to 20-some per 
second, so it's comparable to 25 Hz AC lighting a lamp.  Looking at the 
movie screen you aren't as aware of the frame rate because of your 
persistence of vision, but if you are looking away from the screen the 
frame rate flicker is more apparent.

At least that's what I see ... your mileage may vary, as they say.

73,

Doug, KA2WFT


On 5/13/2015 9:38 AM, Roy Morgan wrote:
>
> On May 13, 2015, at 9:29 AM, Doug Alderdice <ka2wft at arrl.net> wrote:
>
>> Twenty-five cycle electricity was available to commercial customers in the Buffalo-Niagara Falls-Western NY State area,...an old, restored movie theater in North Tonawanda, NY, ... still has the tell-tale 25 Hz flicker.
>
> Does anyone know of a video that shows this 25 cps flicker?  I dimly remember seeing it but very dimly.  heheh,
>
> Roy
>
> Roy Morgan
> k1lky68 at gmail.com
> K1LKY Since 1958