I just bought one of these on ebay:
but want to add MIDI input to it. So I'm using a design posted in Japan http://www.rjblog.net/sx-150mod/... but replacing the MIDI input side TLP522 with a 6N138.
I'm then trying to decide what to do for a DAC on the output side. In that PDF they just put PWM from OC1A through a simple filter but in another design:
they use an Microchip (spit, spit!) MCP4921. So do I:
1) use PWM with simple filter
2) use an R-2R off 8 pins built with discrete resistors (though there maybe accuracy issues as I probably only have 1% on hand)
3) use an MCP4921
4) use a TLC5615 which is another SPI DAC I'm considering
5) use some other form of DAC ?
If so, what? It only needs to be 8/10/12 bit I guess but DIP would make this old verboard hackers life easier! I'd prefer a serial rather than parallel interface.
Oh and it wants to be cheap (which is part of the appeal of the 4921). On RS I saw some Â£100 24 bit DACs listed!