By the way, I've changed the topic tag to EE. > This is a true story. Many years ago I had a friend with just this problem. > A neighbour in a unit separated only by a wall would play his sound system > very very loud in the early hours of the morning (eg 2am - 3am). > > At that stage amongst my junk I had an RF Plastic Welder. 27 MHz ISM band. > Possibly several kilowatts output. > > We placed the welder under the stairs against the internal common wall. > Taped a 27 MHz 1/4 wave whip on the wall. > Loaded the welder into the whip as best we could. > > Left filaments on and with a switch in HT so you could operate instantly. > > 3am. Loud music. Bleary eyed friend stumbles down stairs and presses button. > Loud humming buzzing and other noises from next apartment. After a small > while the sound system was turned off. The problem stopped very shortly > after this but I'm not sure how much the welder had to do with it. > > Interestingly, the affect on a TV in my friends apartment was relatively > minimal - distinct diagonal bars but picture still viewable. I had a similar problem as a freshman in the dorm at college. The guy in the next room had large speakers right up against the thin wall, which was right up against my bed, and he wasn't real nice about keeping the volume down. He liked to study with the stereo cranked. In particular he liked to listen to the campus FM radio station. One day I noticed that he had one of those typical cheap folded dipole FM antennas that looked like a "T" made from TV twin lead, and that the antenna was stuck to the wall I was on the other side of. I had a signal generator that by lucky coincidence could to both AM and FM modulation, and worked up broadcast FM frequencies. It's power output was extremely low, but I put up my own twin lead antenna on the other side of the wall only 3 inches from his. That was enough so that the signal generator could overwhelm the broadcast signal. He couldn't understand why his radio cut out for a few seconds occasionally while I was testing the setup. The ear piece of a telephone worked well enough as a microphone to drive the modulation input of the signal generator, but the sound quality was bad enough to disguise the voice. I waited until one evening there were a bunch of people in his room hanging out eating pizzas, drinking beers, and generally not being very considerate of others. I started by emulating one of those civil defense announcements at a break between songs: "This is a test of the emergency broadcast system. This is a test. This is only a test ... 30 seconds of tone (built into the signal generator). "Attention, attention, an important announcement will follow in 60 seconds" ... "in 30 seconds" ... We were used to emergency broadcast tests, but never followed by any official announcement. People started gathering in the room and outside in the hall. A hush decended as the announcement time approached. This was the Viet Nam era, and people were starting to take this seriously. "Attention, Attention. ... "David Cooperburg " People were rolling on the floor laughing, literally. David was extremely embarrassed and didn't know how to react and flailled around doing stupid things, which of course provided more entertainment, which made it worse, etc, etc. By the time he figured I probably had something to do with it, all the evidence was long out of sight. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body