USB oscilloscopes

[handwire]

Whats the word on USB/PC based oscilloscopes?? Do i need an extra card on my PC?? Can they do everything a physical one?? How accurate are they?? thanks in advance

[Paul Perry (Frostwave)]

If you are in a country (USA) where you can get a reasonably cheap secondhand analog scope, I'd go for that.
But I'd be interested in opinions of people who are using USB scopes, if any are here.
And, the USB scope is entirely external to the computer.

[R.G.]

I use a Picoscope. Works great. It is limited to signals no larger than +/-20V, but most of our stuff can be done with that. A 10:1 probe gets you to +/-200V, not quite enough for tube amps.

But I also have a couple of analog scopes. I find the signal range and resolution of the analog scopes useful, but hate that I can't capture and post-process data. I find the accuracy and capture abilities of the Pico incredibly useful, but hate that I have to be careful not to overvolt it.

[Roobin]

You might want to have a look at http://www.sillanumsoft.org/, which uses just your soundcard!

[R.G.]

Soundcard software is much better than nothing. But it does have its limitations.

One of these, and the reason I bought the $300 Picoscope is that the frequency response of the soundcard is limited to audio. The sampling frequency is usually 44kHz or 48kHz. They have built in lowpass filters to keep signals higher than 20kHz or so from getting in to prevent aliasing in the sampling. So if your effect is oscillating at 25kHz or has RF pickup, you can't see it at all.

Your measuring instruments are your electronic eyes - but it's important to know what they can see and what they can't see.

[miqbal]

Your measuring instruments are your electronic eyes - but it's important to know what they can see and what they can't see.

Cool... RG, that's the keyword. One has to be smarter than his own measuring instrument... but sometimes he isn't, like me

[alanlan]

+1 on the Picoscope, it's a great little piece of kit.  The only down-side is that you need to connect it up to a PC and there's an adaptor i.e. it's not so self contained (edit but mine's a parallel port not USB).  If I really had the money I'd love one of those little Tektronix scopes.

These are the USB Picoscopes:
http://www.picotech.com/oscilloscope.html

[gaussmarkov]

i have been eyeing those picoscopes for a while now.  knowing that you two are using them with satisfaction seals the deal.  now i just have to get it into the budget.