Freeware/DIY soundcard or USB scope suggestions

[tempus]

Hey all;

I'd like to get a PC type scope, primarily for audio, preferably freeware or diy if hardware is necessary. What are you guys using or what would you recommend?

Thanks

[vigilante397]

I've seen a couple USB oscilloscopes on eBay under $100 that looked tempting, but I ended up getting a nice used Tektronix scope instead It's a million times more powerful than I need it to be for most of what I do, but it can save quite a bit of time in debugging. Plus it looks cool on the bench

[deadastronaut]

https://www.zeitnitz.eu/scope_en

[Transmogrifox]

Check out Bitscope. 
http://www.bitscope.com/product/BS05/

They're ~$150 for the micro, but the micro will cover most anything in the audio spectrum, including SMPS circuits if needed (It's 20 MHz).

A really useful tool is audio recording software like Audacity.  You can calibrate by putting in a signal of a known amplitude then you will know how volts relate to the linear scale.  Record/pause/record/pause sequence will help you at least see what's going on in a circuit.  You can zoom in on the waveform as wide or close as you want.

Another thing you can do with Audacity is use it like a signal generator.  You can generate a sine wave, or even play some pre-recorded guitar and capture it all in real time and inspect the waveform.

If you use Linux, there is xoscope, which is software that emulates an oscilloscope using your sound card as input. I don't know much about windows software because I haven't had windows at home for about 6 or 7 years...and at work we use real $10k test equipment.

If you don't use Linux, you can boot a linux distro from a usb key.  If you enable persistence, then install software and changes are saved back to the USB image and persist between boots.

Booting from USB stays away from dual-partitioning or screwing up your existing installation.

If you are a programmer then you could have all kinds of fun with a sound card and signal analysis.

[GibsonGM]

I got a Tektronix, too, for $99 and have never regretted it.  WAY useful!  Throw on an octopus, and you're testing components on the fly...

But, for the computer minded...not USB (I don't think) but works off the sound card is "Visual Analyser", freeware (search for it).  Has a function generator built in.   At our low frequencies, home-made probes would work FINE.  It's what I used to use before I got a real scope and it helped me a lot.

[stallik]

Zeitnitz works well but if you hit the soundcard input with too high a voltage, you can blow the card. I used to use a voltage divider and a cheap usb soundcard for safety sake

[vigilante397]

I got a Tektronix, too, for $99

That's significantly less than I paid for mine

[samhay]

I have a Bitscope micro with a 'HammerHead' breakout board that takes proper BNC scope probes. It's a surprisingly good mixed scope/logic analyser for the price.
However, if you only want to look at audio, then a free PC card-based approach works ok. I can suggest some options that run on a Mac, but unless that's what you're using, they will be of little help.

[GibsonGM]

I got a Tektronix, too, for $99

That's significantly less than I paid for mine

It's a dual channel...only 1 channel worked.  So I took it apart and compared working/non working sides' voltages.  It was a blown diode.  I used a BJT as a low-capacitance diode, popped it in, and it works great!  So, sometimes on fleabay you need to ask questions or you might get a surprise!    Well worth $99 and 3 hours of my time!


As for over-volting your sound card...you can make up a little box with some protection in-line with your probes...zeners to clamp the voltage if you get near whatever the manufacturer says is the max...I would recommend that,  as it's pretty easy to do so!   They won't affect your waveform at our low audio freq's.    There are articles on this on the net...   

[R.G.]

I have an older Tektronix 700 series storage maniframe and multiple plugins. I almost never turn it on - in fact, I don't remember the last time I did. I really should sell it or give it away.

I use a Picoscope. The low end Picos are $200-$350 IIRC, and give me much more than I could get from the Tek in terms of portability, low maintenance, and capturing data. I'm OK with giving up the wider voltage range and higher resolution of the Tek. I rarely deal in nanosecond logic any more. 

There is a Picoscope with two channels *and* an arbitrary waveform generator output. One of these is a fairly complete audio workstation.

[MetalGuy]

Cheap USB scope for under 70$ - Hantek 6022BE. Comes with two probes.

[vigilante397]

It's a dual channel...only 1 channel worked.  So I took it apart and compared working/non working sides' voltages.  It was a blown diode.  I used a BJT as a low-capacitance diode, popped it in, and it works great!  So, sometimes on fleabay you need to ask questions or you might get a surprise!    Well worth $99 and 3 hours of my time!

Now that's a killer deal! I got one of the "older models" for a pretty good deal during a lab cleanout at the school. I picked up three, sold the cheapest and the most expensive, kept the middle one. It's two channels, full color, USB connects to computer or to a flash drive for saving data. Way fancier than I need at this point, but pretty cool