Modding a vintage Morse code keyer with ATmega32U4

Maker repurposes an old-school Morse code into a wireless connected device.

Dating back to the mid-1800s, Morse code refers to a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment. The code was originally developed so that operators could translate the indentations marked on the paper tape into text messages. Recently, Maker Kevin Mitchell put a new spin on the old-school form of communication.


After scoring a 1920s Signal Electric Company code keyer/sounder unit on eBay, the Maker retrofitted the antique machine with an Arduino Yún (ATmega32U4) to transform it into a wireless, web-connected Morse code keyer.

The Yún, which was mounted under the keyer, uses an open-source Morsel API, which enables the vintage device to send and receive messages with other Morsel users. According to Mitchell, when a message is keyed in, the Yún publishes it to the API. When another keyer queries the API for incoming messages, the Yún downloads the Morse sequence and replays it on the sounder. Keeping true to the keyer’s original design, Mitchell added copper electrodes that serve as capacitve buttons connected to the Arduino. The left button plays back the last received message, while the right button sets the replay speed.

Interested in learning more? You can watch the Maker walk through the project above, or head over to Hackaday’s recent write-up here.

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