3 ms·
> when you put the scope probes on, some of the ringing energy goes into the scope and it tends to improve the situation as long as the probe is there. The sof
by a1369209993 3y ago
> when you put the scope probes on, some of the ringing energy goes into the scope and it tends to improve the situation as long as the probe is there.
The software equivalent is so-called "load-bearing printf"s, where for example `printf("broken_var: %i\n",broken_var);` causes broken_var to not get optimized out and so start working correctly. But in hardware that happens even when you (effectively) inspect broken_var in a attached debugger, because the closest thing you have to a debugger (eg, oscilloscope) effectively just is a load-bearing printf.
- mikewarot 3y agoGenerally, a scope probe is best represented as a very small capacitance to ground, followed with a rather large resistance. That capacitance tends to shut most high frequencies to ground. Of course, as things are with the black arts of RF engineering, there are possible situations where that same probe would make things worse, or appear inductive.
- dekhn 3y agoI wonder if the quantum physics equivalent is heisenberg's uncertainty principle. Probably not, but I have observed "observing a detail of a system often interferes with the running of the system"
- dylan604 3y agoIn a past life, I worked in a video post house with a very competent engingering department. Without fail, if we had a problem that required an engineer, they would come in, see the problem, and fix it. Unless, if the only engineer available was the director of the group. The problems were never repeatable when he was present, and everything worked fine. This is why there was a constant request to have a life sized cutout of him to leave in the room to ensure the equipment behaved properly
- mackman 3y agoI usually refer to these as Heisenbugs.