[LAU] [Slightly OT] 312.5Hz

[plutek-infinity]

>Date: Sat, 15 Nov 2008 11:51:35 +1030
>From: Matthew Smith <matt at smiffytech.com>

>Slightly off-topic, but does anyone here know any audio significance of 
>312.5Hz?
>
>I have here a module from a piece of equipment dated back to 1968.  It 
>consists of a 4-pole, 50Hz motor, a printed disc, a lamp and a 
>photocell.  The printing on the disc (rotor) is a wiggly line of 
>changing frequency which - according to the disc - represents a signal 
>between 312.5Hz and 3kHz when spinning at 1500rpm.  You light the lamp, 
>spin the motor, then amplify the signal from the photocell.

very cool. do you have somewhere that you could post a picture of this thing? i'd love to see it!

>What I was wondering was whether end frequencies coincided with any 
>musical notes.

not in the western equal-tempered scale, anyway.
see http://www.phy.mtu.edu/~suits/notefreqs.html


cheers!

-- 
.pltk.