LDR ideas

[Don Tillman]

   From: steve.ridley at bbc.co.uk
   Date: Mon, 27 Apr 1998 16:17:23 +0000

   The LDR-based "mini-theremin" project discussed recently got
   me thinking of other creative uses of LDRs
   1.   A light controlled filter 
   2.   Light controlled all-pass filters 
   3.   Light-controlled mixing.  

Neat idea, but I think we can do better...  These are all things that
are currently trivial to do with regular voltage-controlled modules.
It would be cooler to take more of an advantage of the LDR device by
placing it in circuits that would be otherwise more difficult to
voltage control.  Say for example...
   
  A graphic equalizer with an LDR for each band.
  A chaotic oscillator built with a few LDRs
  A set of, say, three or four BBD delay lines, with the amount of
   delay and the feedback between them all controlled by a dozen
   LDRs. 

That sort of thing.  

   There are a few serious problems with all of these, and the 
   worst one will be the light source.  Under artificial AC lighting,
   there will be 50/60Hz modulation, especially with flourescent
   lights.  

Actually 100/120 Hz.  There's a flourescent flash on both the positive
and negative halves of the cycle.  (Gotcha!)  Yeah, it can be a problem.

  -- Don