My prototype is finally working satisfactorily. I didn't want to say that up to now because I thought I'd jinx it. Also it literally is changing by the day. I'm pretty happy with the hardware and software. I basically took the description of operation of the LM1815 and condensed it down to a program running on a PIC Microcontroller (not shown in the image but goes in the socket). At the end of the day it will probably look a lot like Techguy's. I think he came to roughly the same solution.
Had a nice drive out to test this morning. Good operation in terms of response, minimal overshoot and noise immunity. Reliability is good.
I think the next step is to see if I can condense it all down on a poker chip sized board with SMT components. The pin locations are a little off but I think I can nudge them around by a few mil here and there on my pcb editor.
Installed in the car for testing.
