From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 2020-05-21 22:13, danny burstein wrote:   
   > In  Ralph Mowery   
    writes:   
   >   
   > [snip]   
   >   
   >> Is that a digital or analog scope ?   
   >   
   >> You need to just hang a good old filiment light bulb across the   
   >> generator and see how it looks and measure the voltage with one of the   
   >> old analog meters.  That digital crap often gets confused on oddball   
   >> waveforms.   
   >   
   >> I don't recall exectally the way it works, but in the old days you put a   
   >> piece of greased paper between 2 light bulbs.  One bulb on the generator   
   >> and the other on a good sine wave from the power company and a meter and   
   >> variack and adjusted the voltage so the bulbs were the same brightness   
   >> and then you could read the voltage.   
   >   
   > It gives you a simple and crude way of comparing the   
   > relative brightnesses of both sides of the paper..   
   >   
   > Similar techniques have been used in photography:   
   >   
   > The "Polaroid Swinger [tm]" camera, 1960's, used   
   > a variant of this for its manually operated   
   > light meter:   
   >   
   > http://camera-wiki.org/wiki/Exposure_meter#Extinction_meters   
   >   
   >   
   That's called the "half shade" method, and is actually pretty good.   
      
   Cheers   
      
   Phil Hobbs   
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC / Hobbs ElectroOptics   
   Optics, Electro-optics, Photonics, Analog Electronics   
   Briarcliff Manor NY 10510   
      
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