Wednesday, March 18, 2015

Bride of Synthog gets a 3rd note....10 more to go

The larger IC assemblies are individual notes based on 8038 ICs.  The keyboard will be polyphonic.  The smaller IC at upper right is an op amp that is serving as an adder.  The piece of wood with the wire on it is connected to the op amp.  I connect flexible wires to the 3 notes and touch them to the wire, together or separately.  That aspect of the assembly will become the keyboard.  The assembly is more robust than it looks.  This is ground plane construction.  I like it because you can see everything without turning the board over.  It took me a while to arrive at a repeatable construction method, but now I can do one of these note assemblies in about an hour, plus etching time for the mini-board beneath each IC.  I am using 10 megohm resistors as "insulated" solder lugs.  One end of the resistor is soldered to the ground plane, and connections are made to the other end.  The circuit therefore looks more complicated than it actually is, because there are 4 such resistors per note.  The suspended bare wires are power buses for + and - 9 volts.  There will be another IC at the lower right of the board, and four more in the back....and then 5 more on another board that will be grafted onto this one.

Thursday, March 05, 2015

Bride of Synthog - schematic for two notes

Updated per advice received on  Finally reached my goal of two independent notes.  Now I will expand this circuit with a total of thirteen 8038s for a one-octave instrument.