Note
ARRL Handbook, 1948, page 124.
Radio's Master Encyclopedia , copyright 1939
QST, Feb 1952, p. 125. (Senior, standard, and junior versions.)
Ad in QST, Jul 1978, p. 165 reads "Since 1924..."
Ad in QST, Nov 1979, p. 240 reads "Since 1920..."
Chicago’s Instructograph Co. produced code instruction equipment for more than 60 years. Their machines generated code using punched paper tapes. Early models were powered by spring-driven phonograph motors and were wound up with a crank on the side. A set of contacts keyed an external oscillator or telegraph sounder. Later versions, such as the one in the photograph, used a 110 VAC motor and had internal oscillators. Thousands of amateurs were taught and tested with Instructograph equipment over the years.
