Date: 1959

The stroboconn was invented by Conn in 1936. It is probably tube operated. .

What Conn said in 1959:
Visual tuning eliminates "guess"... SEE the pitch on the disc.... pattern does not move if tone is in tune... moves to the left if tone is flat... moves to the right if tone is sharp. Simple to operate but is the most accurate pitch measuring instrument available. Tuning of any note within the 84 note range (7 octave) is visible to 1/10th of a semi-tone! No adjustment necessary. Trule a scientific frequency instrument that is an accepted standard by leading laboratories. Unexcelled for: piano and organ tuning... teaching proper tuning of band instruments... vocal music instruction... study of physics of sound. Shipping weight 102 lbs. Complete, ready to plug into any standard outlet of 110 volts, 60 cycles.