keying by a microphone
http://www.intio.or.jp/jf10zl/mk.htm
http://www.lightprocessor.co.uk/downloads/mp2d.pdf
http://www.web-ee.com/Schematics/Ultrasonic Range Finder II/UltrasonicRangefinderII.htm
8 channel microphone splitter that can inject phantom power to microphone.
http://www.procosound.com/images/Ms82p.pdf
Sources, calculations, testing of the strings, known good and known bad capacitors for the strings, construction tips and helpful hints.
http://hot-streamer.com/TeslaCoils/MMCInfo/mmcinfo.htm
http://images.electronicsinfoline.com/View/Photo/10001/thumb_multinoisemodule_sch.gif
Multi-function shareware calculator, and unit conversion utility for Windows. Four modes of operation: statistics, trigonomety, base-n, and unit conversion.
http://www.rjsoftware.com/FNA/
Description and construction of a Greinacher or Cockroft Walton generator. The site is in French, but a few places are in English.
http://members.aol.com/_ht_a/lyonelb/greinacher.html
Macintosh digital modes software. Decodes and transmits CW, RTTY, ASCII, SSTV, FAX, ACARS, PSK31, HELL, DTMF and SITOR.
http://www.blackcatsystems.com/software/multimode.html
using two multiplexer ICs and some TTL logic, you can view eight analog or digital (or some of both) signals on the oscilloscope
http://www.edn.com/archives/1997/011697/02di_03.htm