Thank you Ray! I truly admire your stamina to reply to nearly every email and forum post, yet still be able to push the OS project forward.
3.3V from HC595??? The schematic ospi_v13_sch.png from your website shows there’s a +5V regulator that also feeds that chip. So am I missing something? HC595 running even at 4.5V should output around 4V min.
The idea to put an NPN in place of the triac is great! I was going to leave the triac in and just take a wire from the HC595 output to feed into a ULN2803 darlington. If I am unable to replace the triac with an NPN (and the additional resistor), then the 3.3V (if is really that) should still be able to easily drive the ULN2803 (VIL min = 2.4V @ IC=200mA).
Awaiting your reply on the 3.3V question. Thank you again!