These days almost all musicians especially guitarists carry an electronic tuner. They are quite cheap and often come with built in metronomes which are also very handy.
So this brief post is a quick paying of respect to the Stroboconn. The first stroboscope tuner was released in 1936 by the Conn Company.
See, A brief history of the Conn Company.
Stroboscope tuners are the most accurate with some manufacturer’s claiming accuracy up to 1/6 of a cent. (A semitone interval spans 100 cents). For more information go to the Electronic Tuner entry at the website for the all seeing oracle, (aka Wikipedia).