From: blockedofcourse@foo.invalid   
      
   On 2/10/2026 9:49 AM, Christopher Howard wrote:   
   > Line approximation with a resistor-diode has some appeal. Maybe it could   
   > be accurate enough for my little educational experiments? I think, to   
   > pull it off, I would need to use trim pots — two per segment, for the   
   > biasing and the attenuating.   
      
   If you can limit the domain (and thus, range) over which it must   
   apply, you can get good results (for some value of "good").   
      
   We used it to monitor the instantaneous voltage at a thermal   
   prinhead to adjust "print time" (duty cycle) for a desired   
   level of contrast (knowing power dissipated is V^2/R -- R being   
   a device-specific constant).   
      
   But, we only had to accommodate the extent of the "load regulation"   
   of the power supply (when the load can vary from nothing to dozens   
   of amps at a 400Hz rate)   
      
   > The schematic from the neurological paper seemed to be a line   
   > approximation solution with some of the diodes in the op amp feedback. I   
   > didn't try to get the whole research paper so I'm not sure how one would   
   > work out the correct resistor values.   
      
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