Cheap scope for new DIYer

Rene Schmitz uzs159 at uni-bonn.de
Wed Mar 29 23:27:16 CEST 2000


Hi all,

I have done that, using the Soundcard of my old 486 to display the waveforms 
of my early synth modules. I have some nice DOS apps which could do two 
channel scope, X-Y mode (I hacked that myself), and I have even apps 
that perform an FFT so you get a cheap spectrum analyzer. 

The downside of this approach is that the inputs of soundcards are almost 
always AC coupled. Accurate measurements of levels are impossible as you
don't 
know anything about the gain-vs-frequency behaviour. 
(Antialiasing filters -if any-, decoupling caps...)
For example its impossible to trace some switching ripple on your
waveforms, or HF-oscillations in opamp circuits. That can leave you running
in circles.

I'd say for a beginner its a cheap way of getting an impression of your 
waveforms, and there is already a lot that can be done with it, but I'd
recommend 
a scope for any serious work. 

Bye,
 René



At 19:04 29.03.00 +0300, Jaakko Lofstrom wrote:
>Hi all,
>Since this seems to be an ever-ongoing topic, I'll ask the question I
>suppose someone is bound to ask every couple of months..
>
>What's wrong with converting your PC to a 'scope?
>- The way I see it everybody on this list must have a computer of some
>kind; more likely even something equipped with a soundcard
>
>- Oscilloscopes are hideously expensive, especially for a new DIYer who
>has to spend his/hers money to other gear as well
>
>- There's free software to do it
>
>- It's ( mostly ) audio frequency with synths so 22kHz is not a real
>limitation
>
>- Because the to-be user is a DIY-person, it shouldn't be too difficult to
>construct a high-impedance amplifier to convert different voltage levels
>to suitable line signal range..
>
>What am missing here ? 
>Is it the preference to analog synths that's inducing an all-analog
>real-knob-twiddling fixation ;P
>
>No offence; Suppose there has to be more to that driving people to spend
>$$$'s to scopes when they could use it on stuff that makes sounds ;)
>
>-- 
>-jaakko löfström
>...........................................................................
...
>.........,.................................................................
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>...........................................................................
...
>If you stare at the random dots above long enough, you'll see a SPECTACULAR 
>IMAGE OF A LAKE WITH TWO SWANS AND A BUNCH OF SILLY GNOMES IN FULL COLOUR 3D!
> 
>
>
>

opinionsexpressedher   | uzs159 at uni-bonn.de
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