A PIC EG runs on 5V which I obtain using a local regulator. The
output of the EG is a 10-bit PWM signal that is integrated into an
usable voltage. The phase accumulator outputs samples (curves are
interpolated from lookup tables) at a rate of 20KHz. Tom Wiltshire of
SDIY is the one who did the grunt work on this kind of retrofit EG; he
has examples at his web site, electricdruid.net
I designed a KAS replacement, which I need to build one of these
days. It uses discrete DACs and my favorite sneaky way of doing level
shifting of bipolar logic: RS232 chips. (The venerable MC1488, MC1489).
Crow
/∗∗/
David Rogoff wrote:
>
>> The EGs btw are (lowers voice to a mumble) ∗digital∗, using PICs and
>> calculated rate tables similar to the EG-S chip of a DX voice engine.
>>
> A couple of questions here. How fast are the envelope samples? What
> kind of digital/analog interpolation/smoothing are you using? Also,
> I've thought many times about replacing most of the KAS and KBC boards
> with one, cheap FPGA. The problem is that the CS80 runs all the digital
> logic off +8.5v/-6.5v (= 15volt supply) to interface with the analog
> stuff and modern digital chips will fry at any anything over 3.3v. How
> do you handle the PIC? Outboard DAC? A billion level shifters?
>
>