Here are a couple of shots of a PC Based Oscilloscope that connects to the USB. It is the DSO-2150 which I purchased from China on eBay. The total cost including shipping was $200.
Here is a link to the scope on the Hantek page:
http://www.hantek.com.cn/english/produc ... sp?unid=63

It is a dual trace scope with 60MHz bandwidth and a maximum sample rate of 150MS/s. So far it seems to do the trick for me. There is also a FFT function, but I have yet to play around with that.

I have not used it too much so far, but it looks like it will do more than I will require. Also attached is a screen shot of the scope in use. That is a 4.8kHz square wave.

I was searching, yesterday, for a proper way to stop down my rectified DC voltage. I was ALL OVER the web so I dont remember where I saw this. BUT, I saw a DIY build of a USB power source using AA batteries. This might be nice for you and would probably be a cheap/fun little DIY build.

I went and looked for it again. No Luck.
Maybe you could use this
http://gizmodo.com/gadgets/diy/charge-u ... 323132.php

RiGuy

Hi Everyone, The Velleman PC Scope that Gio mentioned is a model PCSU1000. It costs a bit more ($325 US) but has lots of features. Dual trace 60 meg, spectrum analyzer and event logging. Easy to use. It too is USB powered, but has no problems. I have been using it for a few months and it performs perfectly. The spectrum analyzer function is particularly useful. You can see the fundamental, its harmonics and the noise floor all at once. It reads out the frequencies, and in the levels in db or volts. The auto set feature saves a lot of time. It looks at the signal and figures out what settings to use to display it. You can then adjust it if you choose. Usually I find that unnecessary. Screen shots are no problem. They are captured directly. My trusty B&K 30 dual trace is kept only for back up now. For those of you with USB loading problems, the easy way to solve it is with a powered port expander. These devices come with a wall wart and use very little power from the PC.

Good listening
Bruce

Would a sound card based oscilloscope/spectrum analyzer/signal generator be a better choice for audio test & measurement? The reason is that a good sound card can provide 192kHz sampling rate, 24 bit ADC and DAC, very good SNR, THD, IMD....which is essential for HIFI testing.

I used to work at an electronics research/engineering/manufacturer. Our owner was pretty cheap so it took a while to actually get a good scope. We didnt need one right away, but that was our plan B if he didnt approve the $3k one we ended up with. Not my plan B mind you, but the engineer seemed to think he could get away with using it for a while.
Ri

You can use a soundcard and I have done so in the past. However, you need to build an accurate voltage divider network for it. I would also suggest putting in some voltage clamping for protection. A soundcard does not like more than about one volt.

What software package are you looking at?

Here is the very popular and accurate ARTA software, even if in demo version do a lot of things http://www.fesb.hr/~mateljan/arta/

Also a buffer circuit for extra protection: http://xoscope.sourceforge.net/hardware/hardware.html

Anyone ever try running the PC based scope using a Mac and VMware? I would think it would work just fine as VMwware can take control of the USB ports.

While I don't know, I doubt the software took that into consideration so I wouldn't count on it.

FYI - I jut found this

Thanks to the outstanding VMware Fusion team, VMware fixed their bug, worked with PicoTech to fix their bug (bad descriptor) and now, with R5.17.1 from PicoTech, the PS2202 works on Fusion and Boot Camp alike. Kudos to VMware!