Eurorack
Information about the Eurorack standard, with an emphasis on DIY.
Voltages
Eurorack voltages are generally 10 Vpp (typically 0–10 V or -5–+5 V). Those voltages can be audio, pitch information, gates, triggers, or generic control signals.
Power supplies provide +12V, -12V, and optionally +5V. These are passed through 10- or 16-pin headers, pictured below. The 16-pin variety also includes pins for gate and CV, though it's not clear how those are to be used. Not all commercially available modules and power buses utilize shrouded power headers, so pay careful attention to the orientation when connecting modules to power.
