[sdiy] tempco resistors

[Oakley Sound]

 > Am I wrong or all these TYCO resistors have 5% tolerance....?
 > Not quite precises.

Absolute resistance of the temp co is not particularly important since 
you will be trimming the scale factor of the expo anyway. And, of 
course, it all depends on your typical ambient temperature too. You may 
have your design in a box at a typical 40C which the resistance of the 
TC isn't 1K anyhow. In this case, you will trim the VCO/VCF for that 
temp co resistance at that temperature.

What is probably more important is the tolerance of the TC itself. 
+/-10% is not uncommon, ie +2700 to +3300ppm/K, and this is not easily 
trimmed.

Tony