In reply to Harry Veeder's message of Sat, 09 Jun 2007 22:07:05 -0500: Hi, [snip] >Many years ago, before ipods and mp3 players, I had a sony walkman with a >radio turner. >I found that if a pocket calculator were switched on and placed on top of >the walkman I could >move the tuner's dial to particular frequency and hear a faint >"thump.......thump.......thump..." >sort of like a heartbeat. Different calculators generated a similar pattern >of sounds. > >What was going on? [snip] Calculators have their own inbuilt "clock" which is a quartz oscillator, and also divider circuits, so they produce a number of radio frequencies. If the Walkman is tuned to a frequency close to one of those generated by the calculator, then a slow difference frequency will be generated which could be the thump-thump sound.
Regards, Robin van Spaandonk The shrub is a plant.
