In a message dated 10/12/2007, gmvoeth@........... writes:

I am  thinking possibly an optical feedback system using a laser pointer or  
something
to feedback positional data to an  electromagnet



Hi Geoff,
 
    Filament bulbs are fine as light sources for Si  photodiodes. Lasers are 
hideously noisy. LEDs tend to be noisy with the  exceptions of the superbright 
and the IR ones. The light output varies by x5 for  the same current between 
0 and 100 C. You need to stabilise the  output.
 
    Regards,
 
    Chris Chapman
 
    



   






In a message dated 10/12/2007, gmvoeth@........... writes:
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  thinking possibly an optical feedback system using a laser pointer or=20
  something
to feedback positional data to an=20
electromagnet


Hi Geoff,
 
    Filament bulbs are fine as light sources for Si=
=20
photodiodes. Lasers are hideously noisy. LEDs tend to be noisy with the=20
exceptions of the superbright and the IR ones. The light output varies by x5=
 for=20
the same current between 0 and 100 C. You need to stabilise the=20
output.
 
    Regards,
 
    Chris Chapman