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.