[sdiy] basic electronics question - voltage divider

[René Schmitz]

Hi Aaron and all,

Aaron Lanterman wrote:
> That brings up a question - I sometimes see people using op-amp buffers 
> for voltage dividers to create various supply voltages. Buchla does get 
> to +/- 6v needed for the CA3160's in his timbre generator in the 259.
> 
> Oh, I'm still evil, analyzing the equivalent circuit in the Music Easel 
> is Problem 1 on Homework #3. ;)
> 
> Anyway... I'm not sure when one would want to use an op amp for that 
> sort of thing vs. using a dedicated voltage regulator.

Most likely you have those opamps spare. If you need less than say 10mA 
this is ok. If you need more juice you can add some BJTs.

One thing is you get voltages tracking to the rails you derive them 
from. In some cases this is beneficial (i.e. if thereby some supply 
dependance cancels). Regulators drift, introducing several regulators, 
each with different drift rates and his own idea of what 5.0V is, for 
different parts of the circuit isn't makeing the situation better.

Instead of the dividers use good voltage *references* (with tracking 
opamp regulators if neccesary), unlike in the old days they can be had 
for next to nothing todays. (LM336 or so)

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159