Home Telegraph Project Status: TBD
Two station Morse code communicator with WiFi, long range radio, and open source hardware.
Overview
I was inspired to build this after visiting the Exploratorium in San Francisco with my three boys. They had a CW machine with an LCD screen, and it was one of the most fun exhibits in the building, alongside everything else spanning physics, science, art, and more.
Two physical telegraph stations let two people communicate across the house or across a field using Morse code. Tap a paddle key, watch your message appear on a color screen, and hear it beep out of the other station's speaker. It works over home WiFi and can switch automatically to direct long range radio with no internet required.
Signal Loop
The station decodes dits and dahs, the letter appears on screen, and the message is sent to the second unit over WiFi or radio. The receiving station then plays the tone and displays the message on its own screen.
What Stays Local
| Data or Function | Where it runs |
|---|---|
| Paddle input decoding | Local |
| Screen rendering | Local |
| Morse tone generation | Local |
| WiFi message handling | Local |
| Radio fallback transport | Local |
| Message display on receiver | Local |
Hardware
| Component | Details |
|---|---|
| Telegraph key | Paddle key from cwmorse.us |
| Main controller | Heltec ESP32 LoRa V3 |
| Display | 2 inch ST7789 320 x 240 IPS SPI TFT display |
| Speaker | PAM8403 amp with 8 ohm 0.5W speaker |
| Connector | 3.5mm TRS panel mount jack |
| Power | 5V 2A USB C adapter |
Each station uses the same hardware so the pair can act as mirrored endpoints.
Software Stack
| Layer | Technology |
|---|---|
| Input | Iambic paddle decoder for dit, dah, and squeeze timing |
| Display | TFT_eSPI for fast SPI screen rendering |
| Network | ESPAsyncWebServer for WiFi messaging |
| Radio | RadioLib for LoRa packet send and receive |
| Development | Arduino IDE with the Heltec board package |
Build Phases
- Wire one station so the paddle, screen, and speaker work together.
- Add WiFi so two stations can talk across the house.
- Add LoRa radio as an off grid mode when WiFi is unavailable.
- Build an enclosure using a 3D print or a project box.