A laser galvo typically used for laser light shows requires a 10V peak to peak differential voltage to move the galvo position. Ideally that would be +5 to -5, but 0 to (+10 and -10) would have the same effect. A standard DAC on a micro controller has a range of 0-5V or 0-3.3V. This circuit using a 5V DAC will output ....
-10v for a 0V input
0V for a 2.5V input
10V for a 5V input
The rails on the op amps are -15V and 15V. The lower right op amp sets the gain and the upper left sets the offset. The DAC input is the lower voltage input (amber trace). The output to the galvo is the output of the lower op amp (green trace).
The 5V range on the DAC needs to be a 20V range on the output, so we need a gain of 4. That is set with the 30k pot value on the upper right pot.
That negative input gain is 3 (30k/10k). We need an offset of 10, so 10/3 requires 3.33V (blue trace). The upper left pot outputs that voltage into the upper op amp with a gain of 1.
The use of pots allow this to be scale for different DACs and output requirements.
