The poor-man's scope, yes. I still have an AM-radio-sized battery-operated amplifier from Radio Shack in my toolbox, but it's been a long time since I used it.
An AM radio works too, and works above audio frequencies, wirelessly! The loopstick will pick up harmonics off everything in the circuit so you can hear a lot of what's going on. Helps to know what might be going on though.
I had a boss that had retired the following interview question (maybe it was a PhD qual question, I forget): He'd give the candidate a portable TV and an AM radio and have them measure the horizontal scan frequency of the TV. It was probably a chestnut in some circles.
An AM radio works too, and works above audio frequencies, wirelessly! The loopstick will pick up harmonics off everything in the circuit so you can hear a lot of what's going on. Helps to know what might be going on though.
I had a boss that had retired the following interview question (maybe it was a PhD qual question, I forget): He'd give the candidate a portable TV and an AM radio and have them measure the horizontal scan frequency of the TV. It was probably a chestnut in some circles.