7bcc669e   
   From: jasen@xnet.co.nz   
      
   On 2009-12-15, Father Haskell  wrote:   
   > Connect white LED to DVM, point the LED at a light source,   
   > and read light intensity as voltage -- pointing the LED at   
   > the noonday sun produces 1.4 v.  Very cool.  Are there   
   > any problems with this design?   
      
   white LEDs cost more than coloured LEDs and are less efficient in this   
   application.  try with a RED led in an uncoloured case.   
      
   if you measure microamperes instead of volts it's approximately linear   
      
   > I read 0.7 v from a given light source, is that light source   
   > one half as bright as the sun at high noon?   
      
   the LED only responds to frequencies above some limit.   
      
   brightness of light sources is not being measured with that arrangement   
   of optics.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)