Build your own audio oscilloscope, only one tube required. Compliments to Ruven for providing the easy explanation.
Refer the url for a demonstration of this unique (and cheap) 'scope.
http://www.youtube.com/watch?v=HpovwbPGEoo
-F_D
Refer the url for a demonstration of this unique (and cheap) 'scope.
http://www.youtube.com/watch?v=HpovwbPGEoo
-F_D
