Using a PC's soundcard as a cheap, low-bandwidth oscilloscope is a well-known trick - quite frequently mentioned here.
(just google "PC Soundcard Oscilloscope")
Just seen this - the same trick on Android (using the mic input):
http://www.electronics-eetimes.c...
There's also an Open-Source USB add-on board for wider input range, BW, etc:
Bignoob 
Correct me if I am wrong here but doesnt a sound card need a high pass filter to remove DC offset?
i.e a sound card will work for AC coupled signals but not for DC, which to me isn't a very good scope at all
Scopes these days are really cheap, a good unit can be had for not a lot
Torby 
Yes. A sound card is capacitively coupled. Using one is like having your scope channel's "AC-DC" switch stuck in AC. Sometimes you have to interpret.
I love my xminilab from http://www.gabotronics.com/ I also have an xprotolab, the real tiny one, but it seems to have gone naff and thinks the time out for turning off the display is 0 seconds.
If you don't know my whole story, keep your mouth shut.
If you know my whole story, you're an accomplice. Keep your mouth shut. 
Its better than nothing. It is quite handy for decoding infrared and 433MHz comms as you can have a near infinite sample. Time wise it's pretty good, analog wise, its pretty crap. As you mention, close to DC is a problem as the input is ac coupled and much beyond 10KHz is also a problem. Of course, don't expect precision!
The sound card also works as an audio sig gen. You can have it sweep and modulate whilst sampling the input to test your speaker or filter response.
Not bad for a $3 sound card usb dongle.
but it seems to have gone naff
Torby,
You know you can go to Gabriel's web site and download the latest version of the software, to re-flash the device.
JC
Bignoob Kartman I agree with your comments and I can't argue but I can remember the day I acquired my first ever scope, it was a really nice agilent 2 channel new age DSO so I was off to a great start and its still going strong but that scope really really sent me places its the single item that has had the most effect on my life! I would not be where I am now if I hadn't of gotten it and I am serious. The best advice for a budding engineer that wants to do practical stuff is to get one ASAP but I can appreciate some peoples budgets just don't allow it
Doc I am always impressed with your knowledge, you like it technical! kudos to you
Now some days I feel like the luckiest git alive, I have a company credit card and a great boss who is a mechanical engineer, I am actively encouraged to buy things and p!ss about with them I have many thousands of pounds worth of equipment at home for my Uni project, the scope I have is simply amazing it cost a lot and I couldn't go back to not having it. Its easy to vanish up your own arse isn't it but I do remember having nothing and a sound card scope would of been great so I think my comment earlier about it not being a very good scope wasn't a very good comment to make looking back at where I came from
Torby but it seems to have gone naff
Torby,
You know you can go to Gabriel's web site and download the latest version of the software, to re-flash the device.
JC
That's how it went naff. Of course, it's been a couple years since I gave up and bought my xminilab. The bigger one is easier to see anyhow. Maybe I should use the xprotolab to make something cool.
If you don't know my whole story, keep your mouth shut.
If you know my whole story, you're an accomplice. Keep your mouth shut.
Thanks, Bignoob. Nice Scope!
Torby, the Xprotolab comes in TWO hardware versions.
IIRC the earlier version used the parallel interface to the GLCD, the later version switched to an SPI interface, (when the Xmegas were upgraded with USB).
The easy way to tell them apart is that the newer hardware version has the tiny SMT LEDs on the module, the earlier version did not.
Make sure you get the latest driver for the correct hardware version.
JC
Torby
Torby, the Xprotolab comes in TWO hardware versions.
Yes. Mine is the very ancient one. Gabriel didn't figure out why it was behaving so badly and I liked the bigger screen, so I bought his xMinilab.
If you don't know my whole story, keep your mouth shut.
If you know my whole story, you're an accomplice. Keep your mouth shut.
valusoft 
Gabriel didn't figure out why it was behaving so badly and I liked the bigger screen, so I bought his xMinilab.
... at a discount I hope. Buying another product because an earlier one is faulty does not sound like a very good investment...
clawson 
Scopes these days are really cheap, a good unit can be had for not a lot
What can you get for a tenner?
Bignoob What can you get for a tenner?
A probe
http://www.tmart.com/P6100-High-...
And a sound card off ebay
