Instructograph in Operation With A Railroad Telegraph Sounder

A Little History

The Instructograph is an early electromechanical playback device used for learning Continental or American Morse code. Several different models were manufactured by the Chicago-based Instructograph Co. from the 1920s all the way into the 1980s. Learning to receive code is generally a more difficult task than learning to send, and this portable device would allow the student to practice code recognition without the aid of an instructor or fellow student.

Tape Perforations Can be Seen Where Tape Loops Around Post

Reels of oil-impregnated paper tape perforated with dots and dashes were used to actuate a set of electrical contacts that would in turn operate an external railroad-type sounder, a buzzer or oscillator (for tone), or a light for optical communication. The earliest versions of the Instructograph used a wind-up phonograph motor with a variable speed governor to power the rotation of the tape reels.

Other than the mechanical motor, the only other elements in the device consisted of a set of contacts, a battery, and a rheostat to control the current to the sounder or buzzer.

Later versions used a variable speed electric motor for the tape drive, and some actually included an on-board electronic oscillator that would produce an adjustable audio tone.… Read the rest