I dont have money to buy a new oscilloscope
Can I use this oscilloscope for tesing an amplifier output power ?
http://polly.phys.msu.su/~zeld/oscill.html
Would I damage the soundcard with a 40v rms output from the amp when connected to the mic in ?
Can I use this oscilloscope for tesing an amplifier output power ?
http://polly.phys.msu.su/~zeld/oscill.html
Would I damage the soundcard with a 40v rms output from the amp when connected to the mic in ?
40volts into the mic-in ? 
You really shouldn't use mic-in, these are typically very poor, use at
least the line-in, and use a voltagedivider like 47k+1k to reduce the
level down to ~1v rms. Be careful to not exchange cables with
grounding, you might fry your computer and/or amp !
I haven't tried this particular software, but using a pc as scope is
quite good to observe waveforms and do some fundemental thd
measurings...
But it can't replace a real scope to verify stability.
Mike
You really shouldn't use mic-in, these are typically very poor, use at
least the line-in, and use a voltagedivider like 47k+1k to reduce the
level down to ~1v rms. Be careful to not exchange cables with
grounding, you might fry your computer and/or amp !
I haven't tried this particular software, but using a pc as scope is
quite good to observe waveforms and do some fundemental thd
measurings...
But it can't replace a real scope to verify stability.
Mike
40V will smoke a sound card.
I built an external box to act as a buffer/attenuator. It's just a unity-gain buffer (I used a BUF03) with a switchable 10:1 attenuator and an input impedance resembling a scope (1Mohm in parallel with 20pF). In conjunction with a couple of scope probes (a 1x and 10x), I can switch between no attenuation, 10:1 and 100:1.
The sound card route will not really do most of the things you'd want a scope to do because of the very limited bandwidth; it's good for things like spectral analysis, but terrible for troubleshooting or looking at square waves or impulses. A decent used scope can be had for perhaps $200 and should be considered an essential tool. Doing electronics without a good scope is like working on a car without using wrenches.
I built an external box to act as a buffer/attenuator. It's just a unity-gain buffer (I used a BUF03) with a switchable 10:1 attenuator and an input impedance resembling a scope (1Mohm in parallel with 20pF). In conjunction with a couple of scope probes (a 1x and 10x), I can switch between no attenuation, 10:1 and 100:1.
The sound card route will not really do most of the things you'd want a scope to do because of the very limited bandwidth; it's good for things like spectral analysis, but terrible for troubleshooting or looking at square waves or impulses. A decent used scope can be had for perhaps $200 and should be considered an essential tool. Doing electronics without a good scope is like working on a car without using wrenches.
Sooo right. If you don't use a wrench, I guess you are using a hammer.
I measured the input impedance of my SB Live! 24 bit card on line in and got around 8K8. I will retest to make sure as I used a Shallcross decade resistance box and looped line out to line in and used RMAA to show -6dB. I don't know how much it's own output would be loaded down because this computer is no where near my bench.
-Chris
I measured the input impedance of my SB Live! 24 bit card on line in and got around 8K8. I will retest to make sure as I used a Shallcross decade resistance box and looped line out to line in and used RMAA to show -6dB. I don't know how much it's own output would be loaded down because this computer is no where near my bench.
-Chris
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