Home PC-Based DIY Soundcard-Oscilloscope projects

[laserbeak43]

Hi guys,
I've been looking around for some cheap USB oscilloscope solutions
and couldn't really decide, so a buddy of mines tells me about how he
used to blow soundcards on his spare PCs messing around with PC
scopes.

I'm seriously considering giving this a try. there are lots of
documents about ways to safely reduce the signal strength before
sending it into your PC. Each of the examples i'm posting will have
such documentation.

Soundcard Oscilloscope by Christian Zeitnitz:
http://www.zeitnitz.de/Christian/Scope/Scope_en.html
OK, this one DOESN'T tell you how to build the circuit for the
input. It just warns that you need to be aware of the danger. But the
feature list is really nice. It's also made with Lab-View(National
Instruments, the guys that make Multi-Sim). I'll definitely be using
this one once i learn how to make a safe input circuit.

A Soundcard-Oscilloscope by by Ulrich Müller:
http://www.geocities.com/~uwezi/electronics/projects/soundcard_osci.html#history
Yeah, these names won't win any originality contests, but this
page actually has a schematic of the suggested "safety" input
circuit!! This will probably be my choice of scopes to start out with.

BIP Electronics Lab Oscilloscope - 3.0 by Marcel Veldhuizen
http://www.electronics-lab.com/downloads/pc/002/index.html
This one looks a bit nice too. Worth mentioning...

I'll keep you posted on my progress, or lack there-of.

Malik

[laserbeak43]

Just had a successful run with Scope http://www.zeitnitz.de/Christian/Scope/Scope_en.html
i made a simple protection circuit with a 10k pot and 6 1N4001 diodes
that scaled the signal down to ~0.7v.
to test it, i then made a simple Garner's Oscillator. plugged it in,
then powered it up and got a representation of if with some capacitive
coupling( i believe). the peaks weren't square like and had a curve.
There was also a little noise, but this was to be expected with a
cheap sound card solution.

I'll make a page in the pages section of this group board tomorrow
with all of the details and keep updates, since i'll be transferring
the safety circuit to a proto-board of its own eventually.

Malik