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supported by: http://electro-music.com/forum/viewtopic.php?p=395267#395267
new /other solution:
Level shifter from +/ - 5V to 10V
http://www.modularsynthesis.com/modules/DJB-016/djb016.htm
Building:
DPDT switch
i have replaced the ext.start Input jack with a SPST switch, and break only the output signal from the voltage shifter
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