xoscope (sound card oscilloscope)? - Page 1
Forum section: electronics / testgear

author: aphipps
author_rank: Newbie
timestamp: December 27, 2015, 04:36:05 am
content: Does anyone here have any experience with using xoscope?http://xoscope.sourceforge.net/... searching the forum didn't come up with any hits.I'm trying to debug my old Thinkpad that's failing to power on. I suspect the voltage sensing circuit on the MAX1631 (seehttp://kuzyatech.com/fixing-an-ibm-thinkpad-x31) but per the datasheet, that would cause the power to clamp off after 20ms, too fast for my (old, cheap, digital) multimeter to register anything. So I just need something to look if those circuits are twitching. Lacking the proper test equipment, I have already tried replacing the capacitors mentioned in that post but to no avail. So I'm hoping to do some probing.I was considering a Siglent SDS1052DL at the current sale price on TEquipment, but given I haven't needed an oscilloscope in the past 15 years (since college), I'm finding it hard to justify the price - especially considering the Thinkpad is worth less than thatI'm thinking xoscope might do what I need; I use Debian Linux and it's available.What I really don't know what kind of AC coupling sound cards have -- presumably they have a high-pass filter of some sort -- would they even give me anything recognizable on what would presumably be a 20-30ms pulse.Has anyone used this (or similar) and have any experiences to share? Or should I just get the real oscilloscope and hope I find some more uses for it in the future.Thanks!

author: Lightages
author_rank: Unknown
timestamp: December 27, 2015, 01:30:58 pm
content: If you can justify a real scope, you will much better luck. It will be calibrated correctly, high enough bandwidth to really see what is going on, and you will be sure of what you are seeing. A sound card will not be isolated from your computer most likely and you could end up blowing up the sound card too. Sound cards are AC coupled so you will need to bypass the caps at least to see below 10Hz. Of course these things ca be done and there a few tutorials and projects online available to make a sound card oscilloscope but you are very limited in what they can be used for. For your repair I a not sure t would be useful.

author: NilByMouth
author_rank: Regular Contributor
timestamp: December 27, 2015, 02:05:00 pm
content: Quote from: aphipps on December 27, 2015, 04:36:05 amI would avoid anything other than a proper oscilloscope - it will only cause you more problems. Have you looked at getting a second-hand analogue oscilloscope off ebay? You should be able to pick up a working one for less than $100. If you do decide to go for the Siglent range DSO, it's worth spending a bit extra to get one with more memory like the Siglent SDS1072CML ($271) on TEquipment and Amazon. I bought the SDS1102CNL as my first DSO and kind of wish I'd gone for the SDS1102CML, which has the deeper memory. But then I bought it for considerably less than the retail price at the time.Malcolm

author: cdev
author_rank: Super Contributor
timestamp: December 27, 2015, 03:07:54 pm
content: In an emergency, you can use one of an arduino's analog inputs as a crude oscilloscope.With a python script that's floating around out there.Probably a bunch of other devices that contain AD converters could be used as one too. The sampling rate isn't so great, though.I bought a nice used 80s era Tek scope for $75 a few years ago and it works great. Although its bulky its a bit smaller than most of them, and has all the basic features. If you look around you likely could find a similar deal. Its nice to have a standalone scope that does not require a computer to be on and right there.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: December 27, 2015, 07:26:49 pm
content: It sounds rather like aphipps might be needing a good single-shot capture capability, which can be done on an analog scope but takes some considerable skill and a good camera. The DSO is a much better alternative in this case.Once you have the scope, you'll find more and more uses for it, if you have any kind of electronics-related hobby or job.

author: aphipps
author_rank: Newbie
timestamp: December 29, 2015, 06:52:45 am
content: Thanks for the advice.... I'm going to forget about the sound card idea.Using the Arduino's ADC is a great idea cdev.... I do have an Arduino that is currently being used for something else but was planning to replace its current duties with an rpi so it will become free soon. Looks like they can sample at 5kHz and I think that should be adequate for this purpose.However, I will still weigh the digital scope idea... and I appreciate the tip to get one with a bit more memory. The Rigol DS1054Z looks very nice. I'll have to figure out a budget and make a decision.Thanks again!

author: Fungus
author_rank: Super Contributor
timestamp: December 29, 2015, 07:29:32 am
content: Quote from: aphipps on December 29, 2015, 06:52:45 amAn Arduino has no memory to store sample data.PS: The Arduino ADC can actually sample at about 1MHz. The only problem is what to do with that much data.

author: cdev
author_rank: Super Contributor
timestamp: December 29, 2015, 04:07:45 pm
content: When I used it my one need was simply to be able to verify the presence of a very short pulse coming out of a GPS when it had gotten a 3D fix. And using the Arduino I was able to see that well enough to know it was worth soldering a tiny teflon wire to that pin to save some money on an accurate timekeeping GPS.You could probably do that with Xoscope too. xoscope I think also has sync.Here is another possibility?You might also want to see if you could use pins 4 and 5 on an rtl2832u based USB dongle (as little as $10 or even less on ebay) That would get you multi-megs of bandwidth. Dont know about DC coupling, its worth trying.. though.

author: Someone
author_rank: Super Contributor
timestamp: December 29, 2015, 11:10:48 pm
content: Quote from: Fungus on December 29, 2015, 07:29:32 amA '328 has enough memory, we could instead start an old persons rant about the early digital storage scopes.....The OP wants to see if there are some ramps in the power supply and expects 10's of ms, a few hundred samples at 1kHz are still useful and both well known Arduino designs either printing to the serial port (no memory required) or triggering and storing to an SRAM buffer would be a useful place to start.Quote from: aphipps on December 29, 2015, 06:52:45 amIt should get you started and you could explore a 2 channel design or using a GPIO pin for triggering, plenty to work with.