Originally posted by Digitalis In my dorm there was a guy
Ahh yes, dorm living.
One year in residence (aka dorm) in the late 70's, the guy in the adjacent room played his music loud... VERY loud. Requests from his neighbours to turn it down fell on deaf ears. One evening I had had enough, and prepared to move to a study hall to finish my work. As I unplugged my calculator's AC adapter, I heard a distinct 'thunk' next door through the blaring music. Hmm...I plugged it back in and removed it... 'thunk'. Repeating this a dozen times in quick succession (thunk, thunk, thunk, thunk...) caused the guy to turn the volume down. No more thunks. Fifteen minutes later, he turned the volume up again. I repeated. Volume down. This continued for a few nights.
One day he asked me, the electrical engineer undergrad, what I thought the problem was. "Oh, it's probably the equalizing capacitor. It's going into self-feedback oscillations causing the audio amp splitter to reverse polarity through the bridge rectifier. Best to keep the volume down below 4, otherwise the pulses will leak to the other stereo components and the whole stereo system will be burnt out in no time." No more loud music after that.
I've never figured out how my little AC adapter was able to interfere with his system. On the same circuit, no doubt.
- Craig