K3ng Keyer Schematic -
An optocoupler (like the 4N25 or PC817) provides total electrical isolation between the Arduino and the rig.
If your rig does not have a built-in sidetone, or you want to practice offline, the K3NG code features an audio output pin.
+-----------------------+ | Arduino Nano | | | PADDLE | D2 (Left) | TIP ---| | | D5 (Right) | RING --| | | D11 (Keyer Out)-------|--- R (1k) ---+--- Base (2N2222) GND ---| GND | | | | C--+-- Key Jack Tip | A0 (Speed Pot) | | +-----------------------+ E--+-- Key Jack Sleeve | | [10k Potentiometer] GND | GND Use code with caution.
If you want, I can for a specific configuration (e.g., Nano + optoisolator keying + I2C LCD + speed pot). Just tell me which features you need. k3ng keyer schematic
The is a highly versatile, open-source Morse code keyer based on the Arduino platform. Its modular code allows it to function as a simple portable keyer or a feature-rich contest station interface. 🛠️ Core Hardware Setup
Because the entire project is open source, you can fully customize the code and the hardware to fit your specific needs. The software is modular, allowing you to enable or disable features by simply commenting or uncommenting lines in the configuration files. This means you can start with a minimal, breadboard‑friendly keyer and later add a rotary encoder, LCD, keyboard interface, memory buttons, or a CW decoder without changing the core firmware.
Most importantly, the open‑source nature of the project means you are free to experiment. You can change a pin assignment, add a new feature, or even redesign the entire PCB. The K3NG keyer is a project that grows with you: start with a basic breadboard version to learn the ropes, then later build a polished unit with all the bells and whistles. Whether you use it at home, in a contest, or on a SOTA summit, the K3NG keyer is a rewarding build that will serve you for years to come. An optocoupler (like the 4N25 or PC817) provides
| Quantity | Reference | Value / Part | |----------|-----------|---------------| | 2 | R1, R5 | 470 Ω | | 10 | R2, R4, R6, R7, R9–R14 | 1.0 kΩ | | 1 | R3 | 10 kΩ | | 1 | R8 | 100 Ω | | 3 | C1, C2, C4 | 0.01 µF (10 nF) | | 1 | C3 | 220 µF 16 V | | 1 | D1 | 1N4148 | | 1 | U1 | Arduino Nano 3.0 (16 MHz, 5 V) | | 2 | Q1, Q2 | 2N2222A or 2N3904 | | 1 | J1 | 1×4 pin header | | 1 | J2 | 1×2 pin header | | 1 | J4 | 1×3 pin header | | 1 | J6 | 1×2 pin header | | 1 | J8 | 1×3 pin header | | 1 | J9 | 1×2 pin header | | 1 | J10 | 1×5 pin header | | 1 | J11 | 1×5 pin header | | 2 | J5, J3‑PWR | (optional) LED | | 1 | J7 | 2×8 dual row header | | 1 | (optional) SW1 | Command button | | Up to 12 | SW2–SW8 | Memory buttons (or as many as you need) |
Uses a transistor (like a 2N2222) or an optoisolator to safely key the rig's PTT or Key line. Speed Control:
The K3NG keyer is built around the Arduino ecosystem, primarily utilizing the . The Mega is highly recommended for full-featured builds due to its larger memory, which supports extensive features like memory buffers and displays. If you want, I can for a specific configuration (e
The is a highly versatile, open-source Morse code keyer project based on the Arduino platform . Designed by Anthony Good (K3NG), it is widely regarded as one of the most feature-rich keyers available, rivaling expensive commercial units. Core Schematic Components
On an Arduino Nano, the mapping is slightly different, but the concept remains the same: the . You are free to reassign any pin to any function by editing the header files. This flexibility is one of the great strengths of the K3NG keyer schematic—you are not locked into a fixed layout.
Required if you want to enable all software features simultaneously (e.g., display, ethernet, extensive command sets) due to its larger flash memory.
Connect Arduino Digital Pin D4 to a (to limit current).
The project, developed by Anthony Good (K3NG), has revolutionized homebrew amateur radio CW (Morse Code) keyers. It is an open-source, Arduino-based, highly versatile, and feature-rich keyer that can be customized to suit any operator—from QRP operators to dedicated contest enthusiasts.