An update:
I think it's safe to say I'm fairly clueless at this PCB designing lark... Can't get my prototype to work, killed my Apple IIe, house slowly filling with coasters that look suspiciously like PCBs...
Ho-hum, marching on regardless.
I'm up to a Mk4 version of the Mockingchick. Finally got all the ICs to fit on one side of the board, keep the size down to a minimum and managed to route it. Phew! Piccies below:
MK4 MockingChick
Features:
Smallest and so cheapest PCB I can fit a full stereo Mockingboard clone on to.
Finally got all the ICs to fit on one side of the board so no chance of issues with boards in a lower slot.
Minimal component count to keep cost down. (diodes and R3 can be omitted with little loss)
Line out via 3.5mm audio jack that will line up with a knockout if using the default slot (4).
System sound pass-through header. (R3 either a resistor of your choice or use a variable pot)
Optional 4 watt amplified stereo out header for mounting internal speakers
Internal amplified audio auto shut-off if 3.5mm out in use.
Left and Right channels not reversed with this version.
No reset bug here!
For any who are interested I incorporated a header for one of these 4w stereo audio amps based on the PAM8403:
PAM8403 Board
Cheap as chips at 99p a pop if you shop around. Surprisingly solid results, and both smaller and much cheaper than anything I could have incorporated in to this board. Don't need? Don't bother to fit. Have better plans for the headers? Be my guest.
No, this board isn't manufactured, yet. As my previous PCBs have proven very reluctant to get working I'd very much appreciate some advice on my schematic / layout before I inadvertently order another run of coasters.
Links to:
.zip file containing schematic and PCB files for MK4 board (and experimental version using Yamaha YMZ284s instead of AY-3-8913s)
Schematics for two common versions of the Mockingboard to compare with mine.
...for anyone who's feeling kind enough to do a sanity check for me, or anyone curious.
(I'm aware of the lack of decoupling caps for the ICs. They are present in a small revision not shown here)
Many thanks in advance.