? Free oscilloscope

[stallik]

Can't believe that this is not common knowledge here but I'd not come across it so for those not aware, you can download a free for personal use PC oscilloscope software from www.zeitnitz.de/Christian/scope_en
It uses your soundcard, all you need is a probe or two. May not be the most accurate device but as a learning tool it's great

[KazooMan]

Yes, there are several applications for PC oscilloscopes available.  There are also some devices available that provide an interface between the circuit and the PC.  They are probably better, but I would still be concerned about the fate of the PC in the face of significant voltage and current input.

Probably OK for pedals with 9V supplies, but perhaps not.  I would be very wary about using this with anything running off line current.  I can hook up my "real" Rigol scope to the 450 V DC coming out af an amp's power supply and the scope protects itself and adjusts the settings accordingly.  My guess is that this would let the smoke out on a PC application.  I doubt that any PC manufacturer designs their inputs for high voltage and/or current.

[stallik]

Yes, you have to be careful with voltage but usb soundcard dongles are available online for a pound and I've rigged up a simple voltage divider. Also, I'm using an old PC which was destined for the recycling bin so if the worst happens, it's no great issue.
I'm learning how to use it and finding out if it will be useful to me. when I've done that, I'll invest in a real one ( or not)

[GibsonGM]

I started off this way, too, Stallik, but then outgrew the system rapidly.   Currently I've got a 1980's Tektronix 2213 that I got for < $100U.S. off Ebay, which is much more than I'll ever really need - and worth EVERY single penny!    I use my old PC for a signal generator, which is nice but the sound cards don't go over about 22kHz...good for audio, but you can't find unknown inductances with them, for instance...not high enough F to find the peaks/dips.  Eventually I'd like a decent generator.

The reason I mention Ebay scopes is that I did the math, and to assemble some fairly reliable/accurate probes would've taken a bit of time - have to make buffers, interface with the PC...just little boxes, you know, but still time.  And the results would have been 'off' - not true representations of the waveforms due to capacitance issues and the like.   For < $100, I got what I really wanted, and can use it to actually measure rather than just view waveforms.   So instead, I took the time with the little boxes to make a +/- supply amplifier to boost the PC output from .7 volts to 4VAC, useful for feeding into passive networks and stuff.   

The accuracy of a real scope - its ability to really zoom down on a signal and show you the REAL waveform - it irreplaceable, IMO.    PCs give you 'an idea', but you can never actually be sure if what you see is real because they weren't designed for this use.

Good place to get started, but I think that the sample speed will slow down the person interested in REALLY seeing what's going on and who wishes to manipulate waveforms.  Just my 2 cents, by all means have at it!   

[duck_arse]

I've used "xoscope" on my linux machine, but it used to fall over and die on long sweep times. no good for watching slow envelopes decay. that's what the cro is for.

there are designs about for input attenuator/amplifiers to interface probes with sound cards. you'd have to search.

[stallik]

Thanks for the info Mike, I was intending to spend a month or two getting my head round using an oscilloscope then, when and if I outgrow it, get a proper one with all the features that I then know I need. After a couple of days I'm already realising what a powerful tool it is and questioning if the traces are altering due to changes in my circuits or being altered by the system itself. Looks like I will be browsing shortly but with Christmas looming, my family must take priority so perhaps in the new year....

[pinkjimiphoton]

i have an old techtronix scope, all tube. it lived on top of my junk drawers thing, until one day i had left the top drawer open, and the weight stressed the top of the plastic thing it rested on, and it hit the floor from about 5 feet up. ouch.
i think the cathode ray tube took a hit, but there's an assload of precision parts in it.

if someone wants it, for free, and is willing to pay the shipping for it, it's theres.
i'm not gonna mess with it, was gonna sell it but why?

first person hits me up with shipping, it's theres. it's about 15 lbs i think, but not sure.

[pinkjimiphoton]

found this just now...

http://translate.googleusercontent.com/translate_c?depth=1&hl=en&prev=/search%3Fq%3Dkazuo%2Bohtani%2Bstomper%2Bforum%26client%3Dfirefox-a%26hs%3DajR%26rls%3Dorg.mozilla:en-US:official&rurl=translate.google.com&sl=ja&u=http://www.geocities.jp/hy210304/ad100.html&usg=ALkJrhhoIoP-ub42DucxQF68R3m9Y1c14g

oscilloscope to pc adapter

[GibsonGM]

Thanks for the info Mike, I was intending to spend a month or two getting my head round using an oscilloscope then, when and if I outgrow it, get a proper one with all the features that I then know I need. After a couple of days I'm already realising what a powerful tool it is and questioning if the traces are altering due to changes in my circuits or being altered by the system itself. Looks like I will be browsing shortly but with Christmas looming, my family must take priority so perhaps in the new year....

Oh, I understand that, Kevin!  I waited quite a while before getting mine.  Wish I had gotten it sooner, though, as it makes things MUCH easier in terms of really seeing what's going on in a circuit!  You will find one....watch Ebay...for now, given that we're only talking about audio frequencies, you can get away with making a very simple 'PC oscilloscope buffer'. 

There are many circuits out there, as pinkjimi posted - I've seen one based on the TL071, too, more common and it was more simple.    You won't get too much distortion if you go simple, at these low freq's.  Keep it cheap and simple!   It's the card sampling rate that will limit you, mostly.  Home-made probe capacitance (no way to zero it out...), too.   

It will definitely get you more interested and 'ready' to move up, so that's a good thing!