HP150 Touchscreen diagnostic

21 Jan 2011

...

  Vidicons are modern.  
 Do any of your photographic light meters have an adequate IR sensitivity? 
I haev no idea. Quite likely some do, the ones that use a photodiode 
sensor. 

Whenterh they would repsond to a sub-=millisecond pulse (which is what 
the LED output is, I think), I don't know. I think it would be easier to 
homebrew a photodiode+op-amp circuit if I want an IR detector. I don't 
need to make an absolute measurement [1] so calibration isn't a major 
problem.

[1] I susepct that the standard for luminous intensity is one of the 
hardest to get an reasonable approximation to. Photographic exposure 
meters with a log_2 scale, are actually not a lot of use here...

-tony

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HP150 Touchscreen diagnostic