quote: P.S. Why wouldn't you use another opamp to invert? Just curious?
Because Chinese galvos use a 2 wire differential input, and the origional poster wanted to adapt commercial sound card level shifter boards. Those boards he wanted to adapt are single ended, so they would need to invert one channel to get diff, as the alternative is to have to cut a lot of traces on the level shifter and change 2 Rs to make half the amps on the board non inverting.
For many of the non EE or ET types here, adapting the level shifter kit to +/-10 to get full deflection to drive a diff pair single ended with one side grounded is not in their skill set.
ILDA standard is differential anyways, so we should support the standard, and thats 2 opamps for the signal lines or a dedicated national or AD differential sender chip either way.
for protection:
I just stick a 100 or 330 ohm R from the opamp output to the cable load and take the feedback from the load side of the resistor, instant burnout proof for 25 cents at the cost of a small amount off the max cable length and a few mV of offset. But I'm nutz as the mad hatter.
Steve
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...