u9hx@vax5.cit.cornell.edu (05/25/91)
Has anyone out there ever built the parallel port D->A converter to listen to Amiga sound files? (The circuit included in MODPY112.ZIP)? I'm trying to build one, but I can't find an equivalent for the 8 bit d->a converter chip ZN426E.
cejjb@marlin.jcu.edu.au (Jeffrey J Bird) (05/27/91)
In <1991May24.232649.5062@vax5.cit.cornell.edu> u9hx@vax5.cit.cornell.edu writes: >Has anyone out there ever built the parallel port D->A converter to listen to >Amiga sound files? (The circuit included in MODPY112.ZIP)? I'm trying >to build one, but I can't find an equivalent for the 8 bit d->a converter >chip ZN426E. I also couldn't find that chip, so I just built up a R-2R D/A from a handfull of resistors. It works very well, and the circuit is very simple: 2.7K 68 D7 ---/\/\---/\/\---+-------+--------------+-------------------- | | | 5.6K | \ | D6 ------/\/\-------| / 3.3K --+-- .0047uF | \ --+-- 5.6K 5.6K | | | D5 ---/\/\---/\/\---| | -+- | \ - 22K 5.6K | /<-+ 2K D4 ---/\/\---/\/\---| \ | | +--+ 27K 18K | | D3 ---/\/\---/\/\---| -+- | - 180K | +-/\/\-+ | | | | D2 ---+ +------| | 180K | | +-/\/\-+ | | 180K | D1 -----/\/\--------| | 180K 180K | D0 ---/\/\---/\/\---+ This circuit has pretty well the same performance (maybe a little more distortion) and has the added advantage of not requiring an external power supply. Jeff Bird
jgd@Dixie.Com (John G. DeArmond) (05/28/91)
u9hx@vax5.cit.cornell.edu writes: >Has anyone out there ever built the parallel port D->A converter to listen to >Amiga sound files? (The circuit included in MODPY112.ZIP)? I'm trying >to build one, but I can't find an equivalent for the 8 bit d->a converter >chip ZN426E. You don't really need one. An R/2R resistor network across the bits and whose common leg is connected to an amplified speaker does just fine. That's what the Covox Speechthing is as a point of interest. John -- John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm) Rapid Deployment System, Inc. | Home of the Nidgets (tm) Marietta, Ga | {emory,uunet}!rsiatl!jgd | "Vote early, Vote often"