Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: bbirling on June 28, 2010, 08:52:59 am
-
Does anyone here use a pc based oscilloscope ? I have been looking at a product called Soundcard Oszillascope. Are there others that are better. I am cheap and looking for free or something I can build. Having used the DVMM for repair I would like to kick it up a notch when it comes to testing and building.
Bruce
-
Bruce - a search in the Amp Tools section will yield a lot of relevant info.
Chip
-
IMO a basic traditional scope is much better. You can find them for cheap. Dual trace is a big plus. For audio work there is no need for super speeds and other bells and whistles.
-Richard
-
I have had a few. The best so far is a pico scope, but they are expensive.
There are a number based upon sound cards, but dont have any isolation. I betcha a google search will throw something up based on a sound card that has isolation.
-
I asm finding tons of info, maybe to much. I would go with a basic scope but trying to keep the costs at a bare min. I wil check into the sound card ones with the isolation if I can find one.
Bruce
-
I think the same as Richard
but if you want to try a Virtual Instrument
http://www.virtins.com/page3.html
however a 5Mhz or a 10Mhz scope will work fine
PRR Docet
Kagliostro
-
For connections and protected connections
look at page 31 and 32 of the manual
http://www.virtins.com/MultiInstrumentManual.pdf
Kagliostro
-
kagliostro
Thanks a ton. This is exactly what I was looking for. I have a laptop floating around here that I am going to use exclusivly for this.
Bruce
-
> Soundcard Oszillascope.
Soundcards are 10K impedance and accept 2V max (some a little more, some less) audio and !zero! DC.
Signals inside a tube guitar amp run 20V audio and 200V DC at 40K+ impedance.
Connecting a soundcard (even "protected") inside a tube guitar amp will load and mis-shape the signal you hoped to observe, and blow-up the soundcard. (Possibly the whole PC.)
> I have a laptop
The "sound card" is tightly integrated with the laptop main board. So the dire result is not just "no sound" but probably "dead laptop".
An *important* detail of a bench 'scope is the high input impedance (little loading) and wide-range attenuator (can take small or LARGE signals). You don't get that on a sound card. You may get that on the PC-connected external gizmo, but some I've seen only go to a few dozen Volts (ample for anything today *except* tube guitar amps), and anyhow that's $250.
A minor detail is that sound cards think "sound" goes to 20KHz, sometimes 50KHz, with VERY sharp cut-off. The lamest factory 'scope I ever used claimed 450KHz (honestly 200KHz). While you can learn a lot inside a 20KHz limit, in some odd cases it is VERY useful to have a clue what's happening just above the audio band.
IMHO, the most-crude and rude 'scope is much more suitable than a PC.
You could build a buffer for a sound card. Be a fair amount of work.
Heck, you can build a 'scope. DuMont did it. _I_ did it (in the gutted hulk of a DuMont 'scope). Not much more to it than a Champ.
-
Notwithstanding PRRs comment, if you really want to do a scope on your PC (like to capture images) there are some small ones avalaible for $150 that have high input impedance and are isolated. They plug in via USB.
Just google "USB oscilloscope"
Here is one I found. No recommendation for it, I just found it. Max 300V with 10X probe.
http://www.rapidonline.com/Tools-Fasteners-Production-Equipment/Test-Equipment/Oscilloscopes/USBscope50-1GS-s-Digital-storage-oscilloscope/77922/kw/usbscope50
-
OK, so I conceded to spending a few bucks on a scope. The laptop I could use for some other venture.
Thanks for all the responses and insight.
Bruce