K3ng Keyer Schematic Repack [ SIMPLE ]

Analog pin A0 connected to wiper of 10k pot. The repack reminds: “If not used, comment out #define speed_pot_pin” in the firmware.

: This is the starting point, often a simple schematic showing an Arduino (like a Pro Mini or Nano) connected to a few key components like a piezo buzzer for sidetone, a speed potentiometer, and a connection for a straight key or iambic paddle. It’s an excellent blueprint for understanding the fundamental electronics at play.

Many repacks also include an (4N25 or PC817) for better isolation, with clear jumper settings for straight vs. Iambic modes.

: A 2N2222 or BS170 N-channel MOSFET can be used for classic positive-voltage keying lines. A k3ng keyer schematic repack

: A 10k Ohm potentiometer connected to an analog pin (often A0) allows for instant WPM adjustments.

Using a standard 16x2 LCD display via an I2C backpack reduces the necessary wire count from sixteen down to four. Connect to Arduino pin A4 . SCL (Clock Line): Connect to Arduino pin A5 .

However, builders looking for a clean "repack" (a consolidated, optimized, and modernized version of the original schematic) often struggle to find a single, unified circuit diagram. The original documentation is intentionally modular to support dozens of different Arduino boards and options. Analog pin A0 connected to wiper of 10k pot

So go ahead. Download a repack, breadboard the circuit, upload the firmware, and tap out your first “CQ CQ CQ DE YOURCALL.” The bands are waiting.

: Repacks often include a simple RC filter on an analog pin to decode incoming Morse code from a receiver.

Its modular code design means you can easily select which features to include, which is why the "repacks" exist. The K3NG code can be flashed onto a standalone AVR chip or a full Arduino board, giving hardware designers incredible flexibility. : A 2N2222 or BS170 N-channel MOSFET can

I can help identify the best schematic for your chosen setup. Share public link

The repack provides two schematics: one for a simple NPN driver, one for a reed relay. For a modern solid-state rig, build the 2N2222 circuit. The repack shows an LED in parallel with the transistor base for visual keying feedback.

So, you have a schematic, and you're ready to build. How do you move from theory to practice?