Funny you mention that, I've got a Data Translation DT2766 and it is
identical to the AAV11-C. I mean identical! In the day DT must have
sold them based on 2 selling points: (1) Cheaper than DEC and (2) Exact
drop in replacement for the DEC AAV11-C.
Doug
On 7/11/2023 12:33 PM, Nigel Johnson via cctalk wrote:
You might try looking for Data Translation products. I know some of the later
ad and da modules were made by them for DEC
On July 11, 2023 12:28:43 p.m. EDT, Douglas Taylor via cctalk
<[email protected]> wrote:
The DACs on the AAV11-C board are not marked in any revealing way. I think
they are Burr Brown DAC80, 24 pin, but I'm not sure. I wasn't sure if they
were working and was looking for a replacement.
Looking at the spec sheets DAC's seem to come in Voltage or Current versions.
Life got more complicated.
This started out as a simple exercise into verifying the AAV11-C operation
using PDP11GUI to program up a basic program to run all the codes thru the DAC.
It worked, got a ramp out. Now, I'm starting to look at the KWV11-C and how
to use that to send values to the DAC at a controllable rate.
Doug
------------------
On 7/11/2023 11:41 AM, Mike Katz via cctalk wrote:
I originally used R-2R DACs but I was lucky enough to be able to buy a couple
of DAC08 chips at Radio Shack and built a circuit using 74LS244 latching
buffers so that I could drive both channels of a single 8-bit parallel port and
2 extra control lines (Select and Strobe).
On 7/11/2023 6:43 AM, [email protected] steven--- via cctalk wrote:
On 07/10/2023 11:31 PM AEST Mike Katz via cctalk <[email protected]> wrote:
Way back in the 80's I was able to do stereo 4 part harmony on a 2 MHZ
6809 using two 8-bit D/A converters.
Much the same here. I recounted this on VCFed a few months ago about building a
simple 2-chip 8-bit ladder DAC with one-transistor amplifier for my Applied
Technology DG680 S100 machine back in the early 80s from this absolutely
excellent BYTE article on how to do polyphonic synthesis on a microcomputer
(KIM-1):
https://archive.org/details/byte-magazine-1977-09/page/n63/mode/2up
A schoolfriend who had an Apple ][ and had not done any Z80 machine code before
asked for me to hand him my Zaks book, upon which he wrote out one attempt in
Z80, crossed it out and wrote a second version. Which worked perfectly. For the
music piece I got it to play four-voice polyphony after painstakingly encoding
Bach's Praeludium in C Major from my mothers' collection of piano music scores.
A few years ago I had thoughts about porting the 6502 code to the PDP-11 and
use the same sort of ladder DAC. Not sure if the slimline 11/05 would be fast
enough for anything too high frequency, but if it was, the slimline 05's power
supply could then temporarily come out and be perhaps be powered off some beefy
batteries in that space, along with a small 1970s transistor amp and 1970s
headphones topped off with a leather shoulder strap to lug it around like a
giant Walkman.
