Buchla Lopass Gate 292c

Infos:

http://www.naturalrhythmmusic.com/naturalrhythmlop.html

http://modularsynthesis.com/nrm/lopass/

http://www.dragonflyalley.com/constructionBuchla292c.htm

Buildguide:

Resonant Lopass Gate Build Document.pdf

by usage of a Rotary Switch - we needed six wires - we have five colors - so we marked one of the white ones with a bit of heat shrink. We later removed the heat-shrink from the switch-end 'cause we realized it would be in the way - but we immediately soldered that wire to the switch pad A. Here's how the wires worked out:

S1 - red - switch pad 3
S2 - marked white - switch pad A
S3 - green - switch pad 12
S4 - blue - switch pad D
S5 - white - switch pad 7
S6 - black - switch pad C

BOM:

DJB Lopass Gate Mouser parts list.pdf (with mods from http://modularsynthesis.com/nrm/lopass/ )

Lopass Gate Parts List.pdf (original with "failures")

Schematic:

RLPG 3.2 Schematic Diagram.pdf

Bugfixing: (copy from naturalrhytm)

This board has gone through several revisions from 3.0 to 3.4 now. The basic build guide in the docs works for every board. The changes in each revision can be attributed to adding the Euro power connector and optimizing circuit traces more than any other factor. However, revision 3.2 of the board requires one *tiny* jumper due to a circuit trace that got separated from the ground plane when I beefed up the thickness of the traces. The fix is to jumper a pin 5 of the mixer IC to ground (Which can be found on pin 10 of the same IC). This error was fixed for revisions 3.3 forward.

Frontpanel:

FrontDesign [1U MOTM Lopass Gate.pdf

1U MOTM Lopass Gate.fpd

2U MOTM Lopass Gate.fpd

FrontDesign [2U MOTM Lopass Gate.pdf

Misc:

RLPG 3.2 Pads and Silkscreen.pdf