This is the most critical part of the schematic for radio integration. The K3NG keyer must "key" a radio (short the radio's key jack to ground) and provide audio feedback (sidetone).
Two common variations appear in K3NG schematics: k3ng keyer schematic
While there is no single "universal" schematic due to the project's modular nature, most builds follow a standard architecture centered around an Arduino microcontroller. This is the most critical part of the
Always start with the official K3NG GitHub repository schematic for your specific Arduino variant, and never omit the reverse protection diode on the key output—your transceiver’s finals will thank you. Always start with the official K3NG GitHub repository
The schematic distinguishes itself in how it handles (dit/dah). Instead of simple pull-downs, it uses the AVR’s internal pull-up resistors (20k-50k ohm).
Supports LCD displays (classic 4-bit or I2C), rotary encoders for speed control, and even PS/2 or USB keyboards for PC-free CW operation.