I tried a new cable on the dso nano and it works much better. So,
   flashing the firmware of that is available now.

   On Wed, Apr 6, 2022, 3:23 PM Undiscussed Horrific Abuse, One Victim of
   Many <[1]gmkarl@gmail.com> wrote:

   I asked in the old rtlsdr chat regarding this and learned about
   buffering, and electrical engineering concept.
   Without sorting buffering out, I did find I have an optoisolator, a
   potentiometer, and a few transistors from the nyansat kit. I wired the
   potentiometer in and just judging it visually, it kind of looks like
   there is a weak association between value and voltage from 0V-1V and
   then a very strong association from around 1V-1.4V or something like
   that. It reminded me a little of the shunt resistor diagram from the
   laptop. (I also saw different, less distinctive, behavior when reverse
   polarized).
   I recall there were also strong spikes seen when tuned to a frequency,
   when the voltage changed.
   So basically this isn't going to be an oscilloscope quickly, but would
   indeed work as a quick and messy logic probe.
   I'm thinking I might just kind of move forward on logging data from the
   lines in any adhoc manner that can be correlated.
   The rtlsdr maybe has more utility than the oscilloscope here, because
   it has an api I can wire to data storage and event information. Even if
   the signal is heavily transformed by shoddy circuitry.
   I do not have anything visual at this time. I am just looking at
   scrolling numbers.
   Assuming I can work through the double inhibitions, logging multiple
   event-synchronised signals and plotting them would be a good step for
   me.
   Maybe in c/c++ so the code would be easily portable to a more embedded
   device that might be capable of bitbanged probing.

References

   1. mailto:gmkarl@gmail.com