I'm building modular synthesizer cases with built in power supplies (which provides -12V, GND, +12V and +5V). The -12V rail can sink more current than typically required, so I got the idea to add some case lighting with some WS2811 LEDs and a teensy, both powered from -12V and GND.
This has worked fine for a passive (no inputs) version. But since this is a modular synth case, I'd like to add some audio or DC control voltage inputs to the teensy to affect parameters in the LED code. The inputs will be in the range -5 to +5V, and will need to be shifted and scaled to match the inputs for the teensy (-12 to -8.7V). This should be a simple matter of finding a rail to rail opamp with (Vdd-Vss) >= 24V and which saturates very near Vss. But I am a little worried how the teensy ADCs will behave being that the 0V reference is now the -12V rail, I'm wondering if this will introduce noise on the control inputs. Does anyone know of a better way to accomplish what I'm trying to do? (power LEDs from the negative supply whilst controlling them from bipolar inputs) Thank you!
Illustration attached for clarity sake.