Bob Larter wrote in message
...
N_Cook wrote:
Would you adam and eve it? I seem to have made a peak limited (grey?)
white
noise generator.
I wanted to see if the DAC was still working as there is 5V on the
supply
and the datasheet recommends 3.6V and absolute maximum of 4.6V. I cut
data-in line, pin 4, of AK4352VT, from the main Boss chip and connected
,
via 1K, to pin 9 , data out, of the ADC AV5353VT.
Maximum allowed on the ADC is 6V supply and of course absolutely no
technical data of any sort on the www for the DD6 so anything I can
establish is new territory.
Feeding sine in, the ADC o/p datastream varies on frequency. No data
into
the DAC then nothing out. Connect datastream and there is 2V peak
limited
white noise on the analogue output. Varying sine input or even
disconnecting
makes no observable difference to the noise output. Scope shows no
obvious
periodicity 100Hz to 100KHz, and sounds like white noise. Other select
lines
are still connected but what , in principal, is occuring ? Presumably
the
DAC is still working, both channel o/ps have this "white" noise.
Sounds like something's wrong on the input side of the ADC. Have you
tried using a scope to follow a signal from the input socket to the ADC?
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
I did introduce the sine at the 1/4 inch inputs , and op-amps between but
scoping the ADC inputs , they are fine. Curiously my first job in
electronics was constructing a psedo-random sequence generator, filtered
down, to produce peak limited "white noise". For RF transmission line
testing , so requiring MECL logic , rather than for audio. No longer have
access to a spectrum analyser, but would like pass it through one.
There are (scope measured) 50K, 400K, 11M clock and other pulse trains and
not determined whether they are as should be , at the moment just an
interesting curiosity. It is stable , invariant to ps voltage change from
4.3V to 5V.
Not grey noise or any other "coloured" noises that I can find reference to.
The pk to pk maximum is 1/2 the power rail voltage of 5V, so no nasty short
duration peaky spikes of real noise that cause their own problems over
transmission lines IIRC.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/