Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mgm.mit.edu!wolfgang From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht) Newsgroups: sci.electronics Subject: Re: Jamming walkmans (electronic zappers) Message-ID: <1803@bloom-beacon.MIT.EDU> Date: Fri, 13-Nov-87 11:00:00 EST Article-I.D.: bloom-be.1803 Posted: Fri Nov 13 11:00:00 1987 Date-Received: Sun, 15-Nov-87 08:09:30 EST References: <4149@utai.UUCP> Sender: daemon@bloom-beacon.MIT.EDU Reply-To: wolfgang@mgm.mit.edu (Wolfgang Rupprecht) Organization: Independent Software Consultant Lines: 49 Keywords: jamming noise interference broadcast nasty In article <4149@utai.UUCP> cda@utai.UUCP (processor) writes: > I'd like to build a walkman jamming device for >use on the train. One for walkman radios would be >easy, but of little use. Any ideas whether a >short-range tape-recorder jammer (i.e. noise >generator) is feasible? Any suggestions for >such a circuit are welcome. Sounds like a few surplus SDI giga-joule capacitors and a few loops of wire will do the trick. Problem is you and the jammer will hardly fit in the subway car by yourselves. You won't have to worry about some urchin coming along blasting a tape deck in your ear. Oh yes, you will have to watch out for pace-makers too. Not really desirable to shut grandpa down in the attempt to quiet a tapedeck. Now for a fun kinetic energy weapon design. I built a few of them back in highschool. Take all the large 200v capacitors you can find and tie them all together in parallel. The more, the better, at least a few 100 uF's are needed to do anything. Tv power supplies are a good source for these. Add a charging circuit (a bridge from an isoloted 120 vac with a several watt ceramic 100ohm series resistor is cool). Find a plastic tube, 6" long with a 1/4" bore. Mount a coil of several hundred turns on the plastic tube. drill a small hole ~1/2" below the coil, and insert a small plastic piece to act as a support. Leave plenty of room for air to rush around this support. Now drop a ferrous object down the tube, and energize the coil. I used a spdt push-button switch which would alternately charge the caps via the resistor, and discharge them via the coil. If you have a strobe you can probably adjust the timing such that the field collapses just as the launched object passes the coil. Now if you build this: PLEASE BE CAREFUL, 200v can KILL YOU. The launcher on the other hand is relatively safe, it probably won't do more than give you a bruise, unless you are looking into the barrel as it fires, etc. (At least mine never had much umph. Even though I experimented with various L/C/wire-guage/coil-to-object-spacing combinations.) Oh, I should also mention. The caps aren't really designed for this sort of abuse (no kidding wolfgang!). The plates will fatigue from the combined forces induced by a rapidly dropping e-field and a quickly rising m-field. You will hear a distict as the plates move during "launch". What gets really exciting is when one of them finally shorts out. Hint: Don't leave out the charging resistor. You can also add a 1-amp slow blow fuse. Be warned. Wolfgang Rupprecht UUCP: mit-eddie!mgm.mit.edu!wolfgang (or) mirror!mit-mgm!wolfgang ARPA: wolfgang@mgm.mit.edu (IP addr 18.82.0.114)