Here is one using a sound card for the input:
http://polly.phys.msu.su/~zeld/oscill.html
For a more diy approach, try
http://www.ee.washington.edu/conselec/CE/sp95reports/guterman/final/scope1.htm
I tried to do this about ten years ago with limited success, probably because of the slow processor and limited resolution of the sound card. I expect with a modern setup you should get fairly decent performance.
Dave
Happy New Year!
http://polly.phys.msu.su/~zeld/oscill.html
For a more diy approach, try
http://www.ee.washington.edu/conselec/CE/sp95reports/guterman/final/scope1.htm
I tried to do this about ten years ago with limited success, probably because of the slow processor and limited resolution of the sound card. I expect with a modern setup you should get fairly decent performance.
Dave
Happy New Year!
yes with limitations
I've been successfully using mine.
I have an athalon 2Ghz machine with an audigy II ZS sound card.
I also made a preamp to put before the sound card, which has switchable attenuation/gain of .01 .1 / 1 10. Got it from Jaycar was an Electronics Australia design. http://www1.jaycar.com.au/productVi...&pageNumber=&priceMin=&priceMax=&SUBCATID=432
Note that I changed the opamp to a better one which also required increasing the power supply (I used a 12V SLA battery). You definitely want something like this if you are going to be measuring any largeish voltages, or you will likely fry your sound card. (don't try anything above about 3V without it!).
I have been using TrueRTA (the free version) and it is pretty good as long as you are measuring freqencies below about 10Khz. I think this is a limitation with the software or possibly my graphics card (Geforce II GTS). Basically if measuring a sine wave (which has been output by the sound card) over 10Khz, the displayed waveform looks more and more distorted (more like a triangle wave when getting to around 15Khz, and virtually unrecogisable at 20Khz).
One thing it is useless for is testing whether or not your amp is oscillating supersonically definitely only usefull in the audible range.
Here are some links to threads where I have posted CRO screenshots, when testing my amp.
http://www.diyaudio.com/forums/showthread.php?postid=248705#post248705
http://www.diyaudio.com/forums/showthread.php?postid=286873#post286873
and finally (if there wasn't enough already ) a link to the rmaa tests I did on the soundcard and the soundcard preamp.
http://home.swiftdsl.com.au/~tonywww/rmaa/preamp_compare_MKII.htm
Note I haven't tracked down where the 50Hz spike comes from when testing with rmaa but its not there when using as a scope!
Tony.
I've been successfully using mine.
I have an athalon 2Ghz machine with an audigy II ZS sound card.
I also made a preamp to put before the sound card, which has switchable attenuation/gain of .01 .1 / 1 10. Got it from Jaycar was an Electronics Australia design. http://www1.jaycar.com.au/productVi...&pageNumber=&priceMin=&priceMax=&SUBCATID=432
Note that I changed the opamp to a better one which also required increasing the power supply (I used a 12V SLA battery). You definitely want something like this if you are going to be measuring any largeish voltages, or you will likely fry your sound card. (don't try anything above about 3V without it!).
I have been using TrueRTA (the free version) and it is pretty good as long as you are measuring freqencies below about 10Khz. I think this is a limitation with the software or possibly my graphics card (Geforce II GTS). Basically if measuring a sine wave (which has been output by the sound card) over 10Khz, the displayed waveform looks more and more distorted (more like a triangle wave when getting to around 15Khz, and virtually unrecogisable at 20Khz).
One thing it is useless for is testing whether or not your amp is oscillating supersonically definitely only usefull in the audible range.
Here are some links to threads where I have posted CRO screenshots, when testing my amp.
http://www.diyaudio.com/forums/showthread.php?postid=248705#post248705
http://www.diyaudio.com/forums/showthread.php?postid=286873#post286873
and finally (if there wasn't enough already ) a link to the rmaa tests I did on the soundcard and the soundcard preamp.
http://home.swiftdsl.com.au/~tonywww/rmaa/preamp_compare_MKII.htm
Note I haven't tracked down where the 50Hz spike comes from when testing with rmaa but its not there when using as a scope!
Tony.
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