Note
Radio News, May 1930, p. 1061. (this ad says established 1901)
The Omnigraph Morse code machine is a device used primarily for training telegraph operators in Morse code. Patented around 1903 and 1904 by Charles Chinnock, these machines were manufactured by The Omnigraph Manufacturing Co. (established in 1901) in New York. Various models were advertised until the early 1930s.
The Omnigraph operates by automatically transmitting Morse code messages. It uses a series of interchangeable notched metal discs (up to 15 at a time), stacked on a spool. The notches represented the "dots" and "dashes" of Morse code. A spring-wound clock mechanism provides the power to rotate these discs. As the discs rotate, the notches on their edges make contact with a lever, opening and closing an electrical circuit. This action produces audible signals (beeps or clicks) through an external oscillator or sounder, corresponding to Morse code characters.
Because each disc contained only about 36
characters, a system of lever arms under the discs could be used to operate a mechanism that changed which disc was being "read." These levers could be used to "scramble" the messages to reduce the possibility of memorization. Users could purchase as many additional discs as required.
The speed of the code transmission could be adjusted, typically ranging from 10 to 100 words per minute, using a mechanical governor, which can be seen in the photos.
Several distinct models and design evolutions were produced. Early models had a single disc that was manually cranked, but later versions featured multiple discs and spring-wound motors, allowing for more complex and varied practice messages.The Omnigraph Company also offered predetermined Morse code messages or varying alphabet combinations on these discs.
Here are some known versions of the Omnigraph:
Omnigraph #1: This was the initial and simplest model. It featured a single notched metal disc that was manually cranked. Early versions of this had a round wooden base, which was later changed to a larger rectangular board that incorporated a telegraph key and sounder.
Omnigraph #2: This model was a significant improvement. It addressed the limitation of the single-disc model by offering a stack of 15 interchangeable notched code wheels. This allowed for more varied practice messages and included both American and International Morse code discs.
Omnigraph #5: Introduced around 1915, this version initially had a single disc similar to the Omnigraph #1, but it later evolved to include three discs. A key feature of the #5 was the introduction of a wind-up motor to automate the rotation of the disc stack, though the manual cranking handle was sometimes still present.
The Omnigraph Junior: This model, released in the 1920s, was a more compact version that used five discs. It also incorporated a spring-wound motor, with a modified mechanism to accommodate the shorter disc stack. There were variations of the Junior, including one built on an even smaller base with an integrated motor and cam mechanism.
The Omnigraph evolved from simple, manually operated single-disc devices to more complex, motor-driven machines with multiple interchangeable discs, reflecting the company's efforts to improve its training capabilities for telegraph and radio operators.
These machines were vital in telegraph training schools, enabling students to practice receiving and decoding Morse code at various speeds and with different message patterns.
