The 911 Envelope Generator is a basic ADSR waveform generator with an S-Trigger input.
Moog 911 Envelope Generator specifications
This is a pretty simple 1 MU module.
This must be a later version as the PCB has selective gold plating on selected fingers.
Two of the 911 Envelope Generators had serial number labels. Moog did not give modules serial numbers until 1967 and started at serial 1001 so these are the 297th and 406th 911s produced after assigning serial numbers. The date of 106-8-69 is a bit odd but if I assume that is August then Moog produced 109 911 Envelope Generators in 4 months.
One of the 911 Envelope Generators was an earlier version with no calibration trimmers. There are three additional transistors on this design.
The output level and CCW sustain levels were right at 0 volts but the attack to full sustain had a glitch that I removed by hand selecting a resistor.
This scope image shows the ADSR waveform output.
There is an adjustment to match the sustain level with the end of the attack level. Too high and you get a step for the sustain. Too low and you get a notch as shown in this scope image.
This scope image shows a properly adjusted sustain level.