On Mar 28, 22:50, Paul Braun wrote: :-) Everyone (at least, everyone in the UK) knows you wind a hundred turns[1] or so of 24swg DCC (double cotton covered) copper wire (actually, I used enamelled copper) on a toilet roll centre, to make a coil about 2" long. I recall one maths teacher using a toilet roll centre for some demonstration in a maths class (nothing to do with radio or electronics). In his distinctive accent, which was all the more noticable to Scottish schoolchildren, he announced that this was a "wiyah fohmah". Despite heckling, he subsequently refused to acknowledge that it might have had any connection with more mundane functions. [1] to be honest, I can't remember the standard number of turns. It might have been less than a hundred, and I'm too lazy to work it out right now. And it doesn't have to be 24swg, you just use whatever you can scrounge. -- Pete Peter Turnbull Network Manager Dept. of Computer Science University of York