can anyone help me with this one?

Many years ago during an army survival course, we were shown how to create a poor man's radio transmitter using a battery, some wire wool and a barbed wire fence as an antenna. In essence, one end of the wire wool was attached to the barbed wire fence, the other onto a battery terminal (a small 9v PP3 was used), the battery terminal was likewise connected in the same way creating a loop. When the wire wool was roughly scraped across one of the terminals the electrical loop created a volume of static or "noise", which was transmitted along the antenna (barbed wire fence). Of course, we are not talking about a tuned radio frequency here, just radio "noise" that apparently can be detected over several bandwidths but over quite some distance. Unfortunately, after 4 days on the course with no food and little sleep, I was not exactly in the best frame of mind for remembering what was being taught!
Can anyone shine any light on this?

regards, Billyboy

Sounds more like a simple radio reciever, not unlike the simple crystal set many kids make from an old tp roll and wire. You can pick up stations from an incredible distance with such a rig. And it would still be useful in a POW camp just for gathering war news and keeping morale up (provided your on the winning side <img src="images/graemlins/laugh.gif" alt="" />) I know I've got more detailed info on this subject lying around here some place but I haven't had breakfast and the coffee has yet to fully kick in.

Ed

Take a look here -> http://members.aol.com/djadamson7/articles/foxhole.html or do a search for foxhole radios.

These are the old "foxhole" radios that were common in WWII. I know that this is a receiving radio, but this maybe be a starting point for your search. I read a website a while ago, that described a POW in Japan turning one of these into a transmitter, but lack of coffee keeps me from remembering where I found it.

Billyboy,

What you are describing is called a spark gap generator/transmitter. Details can be found at http://www.icomm.ca/survival/245fil.don/radio.htm

Basically, by making/breaking high-amp electrical conections you send out pulses of radio waves across wide bands of the AM radio spectrum. It's similar to the AM radio interference produced during thunderstorms. Like regular AM radio, the transmissions can reach suprisingly far. If you know morse code you can blast out an SOS for hundreds of miles. The FCC considers this sort of transmitter to be illegal and will immediately try to locate the source.

-Blast

Wow, I'm up to three posts in one year.

What you are describing can only be a primitive spark-gap radio. Google it up and you will find many easy plans for building them. The lower the power in the quieter the noise out. With a little work a very simple morse code transmitter can be created. The only problem is with being able to hear the response. there you will want a simple crystal reciever which is also easy to build.

This is one link from my google that describes the transmitter well