On-Line #28 17 марта 1996

Железо     Звук

Iron - Record playback of digital audio - digital-analog converter (Covox). 2 classic scheme kovoksa.

                 IRON


(C) L.D.E. SOFT


   In this issue of ON-LINE I continue to publish articles on
gland, associated with the record-playback digital audio
computer SPECTRUM. If in the last issue of the newspaper, I told
of ADC (analog-digital converter), designed to
recording the analog signal into digital form, but today it
go about the DAC (digital-analog converter) or, in common, 
KOVOKS. 


   Further, on the basis of the proposed single-channel 
circuits, you can collect all the famous (?) SOUND DRIVE, which 
has 4 digital channel.



   I invite your attention two classic circuits on kovoksa
based on chip DAC KR572PA1A (B). The first scheme is different
its simplicity, small number of radio and single power supply. 
However, in my opinion, sounds a bit dirty by comparison with 
the circuit number two. That such a scheme is the inclusion of 
the DAC SOUND DRIVE 1 (described in a few below). Both schemes 
with serviceable parts do not require any establishment. But I 
want to note that before installing K572PA1 would not hurt to 
check it, because, judging from my experience buying this chip 
on the radio market, for 10 chips purchased in this series of 
3% of the marriage. Unfamiliar with the DAC man may not have 
noticed this defect in itself, because tend to be pierced only 
a few bits - sounding DAC in this course will be, but as ...



   Check the chip can be as follows: on the prototype kovoksa 
desirable to set the 16-pin IC socket (it makes your life 
easier), to test the DAC by filing direct commands from BASIC 
or assembler. I will explain how to do this: if your kovoks 
connected to the LPT (mainly in the PENTAGON-128), then 
throwing in a port # FB (251), the command: OUT 251, X (where X 
= 1,2,4,8,16,32,64,128), alternating with the 0. 


   If you kovoks depends not on the LPT, and in VV55 (mostly
Profiles, and right channel SOUND DRIVE), then you need to pass 
the port # 7F (PROS) or # 7F, # 3F (for SOUND DRIVE) control 
word # 80, then disposed of the ports: # 3F - right, # 5F - 
left channels for the pros; # 0F and # 1F - left, # 4F, and # 
5F - the right to SOUND DRIVE. With a fully serviceable bits 
DAC should hear the tone, increasing in loudness proportionally 
to the number emitted. Accordingly, the disappearance sound (or 
inadequate volume) after the issuance of the next number, you 
must replace the chip to another. 


   And one more feature: NEVER LEAVE
FREE DIGITAL INPUTS DAC! Otherwise, the DAC immediately exits
fail!


   Now specifically variants of the DAC:


                (OPTION-1, single-supply)

                           C1

            KR572PA1A