The 'Keith Emerson' Moog 901 series oscillator and controller...

video upload by noddyspuncture

"Less than a year after Keith got his Moog Modular, Bob extensively modified his 901 series oscillators and oscillator controllers. He made them much more stable, solid and reliable tuning wise. There are drawings of schematics of his modifications, which are dated February 1971. I have built a 901A oscillator controller and also a 901B oscillator from these drawings and here is the first time I fired them up and got them to work. Initially they didn't work because I discovered that the FET transistor - which I had bought over a year ago and was still in it's 'anti-static' bag - was actually dead..! It probably originated from China...? I can't remember. Anyways, after installing a generic (the wrong) FET from my stock it all started making noises. Of course, being the wrong component it now won't calibrate according to the instructions but I did manage to tweak the calibration controls by ear to get it to play on one of the octave settings. When I manage to source a good FET of the correct type I'm sure it will all behave as intended - or at least I hope so...!"