The commutator is a 12-channel, passive slip-ring unit from Moog (SRA-73683-12; {{:guides:homemade:moog_sra-73683.pdf|datasheet}}; there is a also a similar one called the AC6200-12 but this has more friction).

For two Amplipex headstages, we are only using channels 1-9; these numbers refer to the numbers on the //commutator// in the schematic below (**NOT** to numbers on the D-sub pins):

{{ :guides:homemade:amplipex_commutator_cable-2.jpg?800 |}}

({{:guides:homemade:amplipex_commutator_cable-1.pdf|pdf}} of above diagram, which came from Amplipex)\\

The corresponding wire colors on the commutator are:\\

1 purple\\
2 white/brown\\
3 blue\\
4 white\\
5 green\\
6 brown\\
7 white/black\\
8 black\\
9 orange\\
10 (not used) red\\
11 (not used) grey\\
12 (not used) yellow\\

Each D-sub connector is labeled either “1” (commutator data channels 1 and 2, purple and white/brown) or “2” (commutator data channels 3 and 4, blue and white).

On the Omnetics/headstage side, as can be seen in the schematic, the two connectors have shared inputs. To accomplish this, 5 wires (scavenged from Cat5e ethernet cable) connect the relevant pins from one connector to the next. The colors for this are:

^ channel number	^ color on commutator wire	^ color on “bridge” wire between connectors ^
|5			|green				|green|
|6			|brown				|brown|
|7			|white/black			|white/green|
|8			|black				|white/orange|
|9			|orange				|orange|

{{:guides:homemade:amplipex_commutator1_wiring_mvdm.pdf|This}} has my original (messy) working notes on this when I was building it (MvdM).