I understand that it wouldn't compare with the actual oscilloscope, but this was never meant to be a replacement for oscilloscope. It's just a low cost way to convert available electronics into a portable handy scope for basic applications. It was very useful for me while I was designing a characterization board.
Sampling rate depends upon the analog to digital converter (ADC) used with the Raspberry Pi. ADS1015 has a relatively lower sampling rate of 3.3kS/s. However, I have also used MCP3002 with Raspberry Pi. It has a sampling rate of around 75KS/s for 2.7V (and 200KS/s for 5V), which gives a very good performance.
So, just with a change of ADC, one can achieve better performance. I will probably include support for more ADCs in the library soon.
While looking into various ADC's, I suggest also providing as an option, a reading from the built-in audio interface.
[1] https://www.bananarobotics.com/shop/Educational-PC-Oscillosc... [2] https://www.sparkfun.com/products/9263
I would like to recommend the Rigol DS1052E in that price range, or a used HP/Tektronix analog scope for the sub-$100 market.
It's an improvement, sure, and full scopes certainly don't compete on price. I'm thankful for their efforts. But somehow I can't help but feel that it should be possible to do significantly better.
As a scope though, forget it. You need at least 1-2MHz BW for something usable for even audio applications. At least 20MHz is probably a good idea. I have a 20MHz analogue scope (LG) and it cost me £10 (~$15) which is less than the Pi.
PS. 3K sample/sec is good enough for a lot of work on sensors and also for the youngish to get a handle on how to do ADC and process it - who knows some young person may start of experimenting with something like this and go onto design something quite awesome in the future.
