PC Osscilloscope spectrum analyzer and signal generator for under $30

[slayer007]

In this video I just wanted to show how you can have a osscilloscope spectrum analyzer and signal generator for under $30

I bought this PC Osscilloscope probes off ebay for $22 plus shipping.

The software I'm using is visual analyzer it's a free program.

If you know of any other nice programs please post them here.

Here is a video of it.I'm using a SEC running off 2.8v

YouTube - PC oscilloscope for under $30

[morpher44]

low cost scopes / spectrum analyzer

In this video I just wanted to show how you can have a osscilloscope spectrum analyzer and signal generator for under $30
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Bandwidth up to 96Khz, sampling 192Khz....
I find though, that in practice, the Nyquist rule of divide by 2
doesn't really work here.
2 samples @ 96Khz is not much resolution. You can recreate
a saw tooth wave ... but extrapolating that to a sign wave
or a squarewave, etc. ... problematic.
Divide by 8 is more like it ... meaning 24khz is top end if lucky ..
which is the top of the audio range.
So for audio work ... yes no problem ... makes sense since using
the audio card.
This VA thing uses "full D/A", whatever that is ...
It is likely just software taking care to use highest bit-sampling
possible found on sound card ... and highest sample rate
supported by sound card ... and perhaps some linear or curve
extrapolation.

I too was looking for a low cost PC / USB solution for an oscilloscope.
The DSO-2090 looks impressive ... but I have no experience with it.
It might suck.

I want to mess around with higher voltages and higher frequencies,
and two immediate concerns are ...
[] how do I isolate these high voltages so that they don't creep down
the skin of the plastic probe wire and enter my PC ... destroying
my expensive PC?
Optical isolation would be nice?

[] for 100mhz sampling, I would assume you would need some sort of
embedded device that can sample -- with memory -- and then
you could suck those samples up to your PC after a capture.
Sampling this fast directly to the PC is a bit problematic.

I am looking forward to someone coming up with a low-cost
USB or fire-wire Oscilloscope/Spectrum analyzer.
I'm surprised there are not more choices.

I decided to go slightly lower tech and buy a used Tektronics scope off of EBAY
and then to use digital cameras to "screen capture".

[morpher44]

SPDIF - Dolby Pro Logic II for Oscilloscope

I played around a bit with Dolby Pro Logic II,
using SPDIF fiber cables.

There are 5 channels with this sound device and
you can use a fiber cable.

Turning this interface into an oscilloscope / spectrum analyzer
might make sense because you have more channels
to work with ... for either more bandwidth or
multiple probes.

Fiber is ideal to better isolate your PC from dangerous voltages.

I look forward to seeing someone come up with this sort of solution
in the near future.

[amigo]

If you could individually control each channel and if they could be precisely timed then in theory you could increase the sampling bandwidth of your setup by a factor of channels you have.

Some digital scope makers use that technique to double or quadruple the bandwidth by sequentually using the ADCs (send the same signal to multiple ADC) and timing each of them off by pre-determined clock value (slightly off-phase), then through extrapolation they obtain better sampling and higher bandwidth.

Dave Jones explains this better than me in one of the videos on his EEVblog...what can I say but "crikey."

YouTube - EEVblog #19 - Rigol caught with their pants down!