KorgKorg is a maker of synths, digital pianos, and other music production software and hardware.
Switch - Korg, Momentary Tactile Switch, Under Knob P8012S
Korg Tact switch under knob P8012S. SPST momentary, 0.25in. width.
Optocoupler - Vactec, VTL5C1, Vactrol, New Old Stock
New old stock Vactec VTL5C1 vactrols from Perkin Elmer Optoelectronics. These premium vactrols are a great choice for use in phasers, compressors, tremolos, and synth modules such as low-pass gates. They are also used in switching circuits in amplifiers. Limited quantities are available.