SynthModules

No, I didn't even draw them out.  I used two inverting op amps in 
series.  The first is configured as an adder.  Signal at gain=-1 and
15 volts at gain=-1/3.  The second is configured as an inverter.  I
used TL074 op amps.  I figured out the resistor pattern for a Radio
Shack perf board and then built 8 identical stages.  1/2 of the
circuits connected to the +15 volts for a shift up and the other
half connected to the -15 for a shift down.  I used resistors from
the positive input to grounds to minimize offset.  My worst output
was offset by 7 mV so they are reasonably accurate.

There is a photo of just the perf board in the photos section under 
DJB photos.  You can see the 8 identical circuit patterns.  Let me 
know if you really want a schematic and I will draw one up. I did
for all my other boards.

Dave


--- In SynthModules@yahoogroups.com, "Scott E." <yahudinyhwh@s...> 
wrote:
> Dave,
> 
> Have the schematics for these level shifters been posted anywhere?
> 
> Scott
>