Telegraph

A wireless [morse] telegraph system for the NodeMCU ESP8266 chip

General info

Have you ever wanted to be a 1920s radio operator but didn't want to get a wireless telegraphy setup, a retro morse key and an amateur radio license?

Fear not, Telegraph will replace all three with a NodeMCU and some hardware!

• Uses the NodeMCU v1.0, ESP8266-12E v2 Amica board.
  • There are multiple versions of the NodeMCU with confusing names. This board is the newest official one and has a standard breadboard size. See this article for reference.
• Uses the Thinger.io service to communicate between devices
• Currently only supports communication between two devices, which is the maximum you can have with a free Thinger.io plan
• The morse key for this project uses this 3D-printed design
• Note: pulses less than 7ms in length will be ignored as debounce noise

Installation

1. Build the circuit as shown in the diagrams below
2. Install the Arduino IDE
3. Install the NodeMCU Add-On
4. Install the Thinger.io library from the Arduino Library Manager
5. Install the WiFiManager library by TZAPU from the Arduino Library Manager
6. Set up two Thinger.io devices, called NodeMCU0 and NodeMCU1
7. Modify the preferences under the preferences.ino file to include your Thinger credentials
8. Connect the NodeMCUs to your computer via USB and upload the code

Usage

• The first time you start the Telegraph, it will go into setup mode and shine a red light
  • This will make it into a WiFi beacon
  • Connect to the network named Telegraph with your phone or other device
  • Fill in your WiFi SSID and password into the login webpage
  • After you finish, Telegraph should connect to the provided network and all lights should turn off
  • If the network credentials were incorrect or the device fails to connect, it will simply re-enter setup mode
• Perform the setup procedure and turn on both Telegraphs
• Press the button on one and it will send the signal in real time to the other one
  • Flicking the "mute" switch will shine a dim red light and no signals will be sent
  • You will still be able to practice CW on your own
  • Note that this does not save any power, as the WiFi connection is not turned off due to incoming connections
• Outgoing signals flash the green LED, and incoming signals flash the blue LED on your device
  • Both signals beep the speaker at the same pitch

Circuit

The circuit contains a morse key (which can be any button), a mute switch, a speaker, and an RGB LED light. These are hooked up using resistors and capacitors. A breadboard also helps a lot. The circuit is as follows:

Credits

• Ega on the Thinger.io forum for this wild goose chase of a conversation
• Samuel Morse
• How to exit vim