Little PC scopes

[Enzo]

I am not a fan of the idea of tying up my computer screen with scope displays, but these things caught my eye.

http://www.saelig.com/miva/merchant....uct_Code=PS028



http://www.saelig.com/miva/merchant....uct_Code=PS042



Not just pc scopes, they include spectrum analysis and other groovy stuff.

Main drawback is that they seem to be limited to 50v and 20v. Stil they look interesting, more than enough to chase signals or connect to speakers. Just don't connect it to the 6L6 plates.

[xFallen]

Those are cool aren't they?

If you do not need RF level sample rates there are software only solutions that use the input channels on your PC sound card.

I'd be real concerned about HV coupling to my PC.

My el cheapo 20 MHz sillyscope is limited to 300V peak at the inputs anyway. I suppose one could put some sort of attenuator in front of the inputs.

I have never tried to look at the output tubes of my amps on the 'scope but have always wanted to do it.

Is there a guitar amp o'scope do's/don'ts/tips and tricks page somewhere? I have seen the tutorials on setting bias using a 'scope but that's about it.


Barry

[Steve Conner]

I have one of the Picoscopes, the ADC212/100. The input voltage limit is no problem, you just need x100 probes.

What is a problem is the ease of use of PC-based instruments: it's considerably worse than an analog scope. For instance, changing the Y amp sensitivity or timebase means grabbing a mouse and using a pull-down menu. On a real scope, you just turn a knob, which you can do with your left hand while holding a probe in your right, without really thinking about it. For debugging audio equipment, I think I'd be happier with an old $50 analog scope off Ebay.

[Enzo]

My computer has USB ports on the front panel, three that I can see, whereas my sound card as far as I know is around back. I envisioned plugging the hand probe one into the front of the thing and off I'd go. I'd rather shave my head than pull my computer out from the wall. And I absolutely hate opening it up.

Actually the concern I have about voltage - and it may be totally from ignorance - is not so much the circuit voltage , which I know I can knock down with a dividing probe, but more about grounding. I know nothing about USB. ANd I know I'd always need to hook the ground clip from the scope to the work, but what if the work has a hot chassis or other potential situation. My computer is connected to the earth through the mains, but would the USB port withstand the scope probe ground being connected to an old Fender with a leaky death cap? I hope I articulated that properly.

I know I could connect a X10 or X100 probe to the little box version, but the hand held probe I don't think has a dividing tip option.

I am happy as a clam with my old beater bench scope, so I don't know that I want to shell out a couple hundred bucks for a new toy, but it intrigues me.

[xFallen]

That's basically my concern also. Maybe not voltage but some other thing going wrong that PC designers simply had no cause to anticipate. The USB cable is a four conductor cable with ground, Vcc, and two data signal lines.

How is the conventional 'scope protected against the hot chassis issue?


Barry

[Enzo]

Well my scope has a grounded threee wire power cord. That pretty well covers a path to ground by grounding the scope chassis. SO if I hit something extreme, the weakest link I'd guess would be the little ground wire comng out the side of my probe. I guess it would evaporate.