Shared Projects by squarewave

Daughter board for Roland A-49 MIDI Keyboard Controller that adds analog synth CV outputs for the pitch / mod control (joystick thingy on the left side) making pitch / mod smoooooth and … well analog. Without this mod, MIDI will send 7bit codes which sounds stepped (USB does not have this problem - it’s only stepped when using a MIDI cable). When the ring contact of a jack is not grounded, the A-49 will exhibit stock behavior. Bolts on / plugs in using existing JST connectors. See https://groupdiy.com/index.php?topic=75780.0 for details.

Vactrol compressor side-chain circuit that uses a gyrator to add a “dip” or “ripple” to the control voltage to compensate for the time delay of the LDR. It should be possible to retrofit this into any amp that runs on a dual supply and has a vactrol attenuation element such as the RTS Systems 1400 battery powered mic pre. Note: This is just the side-chain, there is no I/O or vactrol on the board. See https://groupdiy.com/index.php?topic=75212.0 for details.

Replacement output for Roland Space Echo (RE-101, RE-201, etc) w/ impedance balanced op amp output, +12dB boost, tunable bias signal filter and atten. / gain control (-12dB, 0dB, +12dB w/ LMH switch). Replaces existing filter board with new TRS jack. See https://groupdiy.com/index.php?topic=75083.0 for details.