This afternoon, I tried to instil some A Level physics knowledge into Sophia by giving her a practical electronics lesson. Unfortunately, part way through, my trusty oscilloscope made a nasty crackling noise and emitted an unpleasant smell. It did however keep working, so as we were near the end of the lesson we pressed on but switched the scope off whenever it wasn’t needed. My scope is a Phillips PM3217 which I bought more than 30 years ago as unused