I've just completed building the (originally rare) Moog 901C output stage. 

 

This amplifies standard Moog waveform levels for use as a deep modulation source, also generating positive-going and negative-going pulse waveforms. It has two complementary outputs.

 

As the original required a 3-pole 6-way switch, I've added electronic switching of the output waveforms, otherwise it's the original Moog circuit.

 

On the initial PCB run, the slots for the jack socket pins are not correctly cut, so I'm offering them at a reduced price (or free with 901A and 901B PCBs). The build document shows how to modify the PCB.

 

Works with my 901B oscillators, or with Behringer System 55 oscillator modules. 

 

A trial panel is on order.

 901B Oscillator PCBs are back in stock.

The latest PCB version has some minor changes:

- C100 (470uF) changes from axial to radial, as radial capacitors are more easily sourced.

- new option to use a 3 pin "turned pin" socket (half of a 6 pin socket) for the "selected" transistors T7 and T10.

The build document has been updated (V1-1).

 Two videos of my 901A Oscillator Controller with 901B Oscillators, with temporary panel. 

 

General overview (the scaling of the 901A is not optimum in this):

 

901A scaling following adjustment:

 

 

 

 

 Available shortly: DIY (do-it-yourself, build-it-yourself) "Moog" modules in Eurorack format to complement the Behringer "System 55 " modules:

- 901A Oscillator Controller

- 901B Oscillator

-- 992 "Control Voltages" (Control source switching and adder)

- CP3/CP3A Mixer - can be used with the "992" PCB to make console panels, or on its own.

- "Universal daughter board" PCB - to facilitate easy connections to the back of Behringer modules.

Under development:

-  901C Output Stage

-  904C Filter Coupler

-  901 Oscillator

 

 

 

 

 

 

 My prototype Moog 901B in 8hp of eurorack. 2 PCBs, all thro' hole. The rear PCB holds the oscillator, the front PCB holds the sockets, pitch control, range switch and range caps (plus an op-amp as I've added a PWM input).Two Molex connectors on the rear are for the "bus" from the 901A controller, plus one with all of the outputs on it.

The extra pot and wiring in the pictures is because there is (as yet) no 901A controller - the design for the 901A is ready, but no point in proceeding with it until I had a working oscillator!

The output:
 

(any glitches visible on the triangle and sine are because I don't yet have all of the range caps installed - these are also used for filtering the triangle waveform).

While the prototype uses thonkiconn jacks, I'm swapping it (and the 901A) to use PJ3410's, as the Alpha rotary switch sits higher on the PCB than I had originally envisaged. I could also do with using a longer shaft pot for the pitch control.

 

Some of our front panels are currently in short supply.

We are therefore providing complete files for  "Front Panel Designer" to allow customers to order panels directly from Schaeffer AG.

 

Please note:

• We have no affiliation with Schaeffer AG.
• While these files utilise the same FPD files and print graphics that we use for our own panels, we have not necessarily ordered these specific panels ourselves from Schaeffer AG.
• For personnal, non-commercial, use only.
  

 

Currently available: 

 

100m-ish LFO

Silver Ano panel with Black graphics  

Black Ano panel with white graphics    

 

100m-ish Audio Delay

Black Ano panel with white graphics    

(We have plenty of stock of silver ano panels with black graphics)  

 

100m-ish VCO Driver

Silver Ano panel with Black graphics 

Black Ano panel with white graphics   

Polymoog Resonator 

Silver Ano panel with Black graphics

Black Ano panel with white graphics

(While "Moog" is a registered trademark, in the UK "polymoog" has not been regiistered for a number of years.)                          

Black Ano panel with white graphics 

To match Behringer System 55.    

Behringer 904A filter with the AMSynths daughter board installed - this swaps out the Behringer capacitors for matched lower value polyester capacitors as used in the late 60's Moogs. 

Took about an hour to convert - most  of that time was spent removing the original Behringer capacitors (they are thru-hole, the rest of the Behringer circuit is surface-mount). Just used solder sucker and braid - no fancy desoldering station needed.

This now sounds very very nice!