On Thu, March 22, 2018 4:00 pm, Will Godfrey wrote: I haven't checked for recently available devices, but in the not too distant past it was very expensive to get more than 8 usable bits from a device running at multiple hundreds MHz sample rate (not to mention the extra load in the math and processing such as filtering, FFT, difference calculations, etc. resulting from more bits) -- Chris Caudle

Hi Will, On Thu Mar 22 2018, Will Godfrey wrote: They're certainly better than no oscilloscope, but not as good as a real one. Almost certainly your soundcard is AC coupled, meaning it has capacitors in the input path to block any DC signal. There are some guides online describing how to remove the caps on certain soundcards, but I've never tried it. If you're going to be poking around anything but the tamest stuff, you might want some input protection to avoid smoking your soundcard. Again, there are lots of guides online about building a input stage, usually with pairs of diodes to protect against (moderate) overvoltage, and often with a higher impedance, so your measurements won't affect the circuit you're measuring as much. I really like having good probes designed for the job, instead of alligator clips or bare leads. You could put some BNC connectors on your input stage, and get some inexpensive probes online. I would recommend that, if you think you'll use a scope more than just occasionally, and you're not on a really restricted budget or just want to play around with soundcard-based solutions, you'll be better off just going for something like the Hantek 6022BE: 2 channel, 20MHz bandwidth, DC coupled, high impedance inputs, comes with real probes, supported by OpenHantek and sigrok on Linux, for only $60US or so. Whichever way you go, have fun, -Sean

Am 22.03.2018 um 22:00 schrieb Will Godfrey: Bandwidth (or rather sample rate). For probably most applications an oscilloscope is used for, audio being one of the few exceptions, bandwidth is usually more important than resolution and a higher bandwidth requires a higher sample rate to be of any use. Also, higher resolution requires higher quality frontends, that naturally get more and more expensive with increasing bandwidth. You'll hardly find any affordable scope with remotely that noiselevel of a good soundcard. Further there is naturally a significant difference in data between 192kHz and 1GS, latter being quite the standard these days, and that amount of data needs to be handled somewhat accurately by the AD converter as well as the processing backend. So to keep the amount of data managable, you reduce resolution, or increase the price. Anyway, I am unaware that there even is such an AD converter to handle 1GS/16bit+ at all. Anyone? But even for audio I would assume, resolution is more important for fft analysis than for an oscilloscope - though it is not uncommon that a device does both, with of course a lousy front end unless you really spend cash. But, if capturing signals is really needed, like oneshot, 8 Bit, while not a beauty to look at, is usually sufficient for analysis. For everything else there are analog scopes to be had for cheap these days. There are a few DC coupled soundcards out there. A company called expert sleepers is selling devices, that make control voltages for analog synthesizers controlable from (windows) computers, in turn requiring DC coupled soundcards. In that context I believe to have read some discussion about that. Maybe that helps as a starting point. But, as already said, mind your inputs. As a matter of principle always starting out with a 10x probe (there are adapters) would be really sensible behaviour to get used to, if no input protection is in place. And a spare soundcard, just in case...