Summer 2018 - DAC Mux, Ring mod

Summer is always kind of productive for me. While off on summer holiday to the western parts of Norway, I get time to do some electronics work. This time I've drawn up and ordered a 16 channel sample and hold circuit (DAC mux) to replace the 32 channel one used in the prototype. This one is easier to place and makes it possible to use only 16 channels for parts of the synth.

I also did a v3 of the linear VCA. This time, as for the first version, the trimmers are off-board, but the components are placed on both sides as in v2. The whole card is sort of a double width DIL thingy with the pins for one VCA on one side and the other on the other side. I imagine it possible to place it in a socket and have other parts of the circuit below it - we'll see.

Finally, I did a ring modulator based on the one from yusynth.net, which in turn is almost entirely a copy of the one in the datasheet. This one uses a surface mount MC1496. The circuit and board are finished (but untested), including logo.

Oh, and I have written a midi/sysex-based bootloader - it's almost finished. I will feel much better if I can remotely update any MPG-200 I sell. The bootloader is very simplistic and does not have any flow control, so sysex uploading must be done through a program made by me. Still better than not being able to update at all.