[GreenKeys] Tuning Fork

[WA3FRP at aol.com]

Lar, 
 
Yes, that's the use I remember - setting up the speed on governor  controlled 
motors.  As I remember the target end of the motor was painted  alternately 
in black and white.  When the speed was correct, the pattern  would look to 
stand still when looking through the tuning fork.
 
73,
 
Russ
WA3FRP