Moog modular synthesizer

The first prototype Moog Modular Synthesizer, designed by Bob Moog was built in 1964 and by 1967 was a commercially available product line. These were walnut cabinets housing Moog 900-series modules.

The 900-series modules modules use S-Trigger and not the more widely used V-Trigger system. This drops +5V to 0V when a trigger is sent, the opposite of what’s commonly used in other synths, which raise 0V to a higher voltage (from 2V to 10V).