Because the code runs on an Arduino, the schematic is simply the wiring map to unlock these features. You can build a minimal keyer with three wires, or a deluxe command station with 40 components. The schematic scales with you.

The most critical part of the K3NG schematic is the . The paddle inputs rely on pull-up resistors. Look closely at the schematic: you will see 4.7kΩ resistors connected from pins 2 and 3 to +5V.

The K3NG schematic is famously flexible, allowing builders to "enable" or "disable" hardware features in the code to match their specific build: A Simple DIY “Unikeyer” Based on the K3NG Design

: Connects to the positive (+) line of the transmitter key jack.

In the world of amateur radio, few open-source hardware projects have achieved the level of reverence and functionality as the . Developed by Anthony Good ( callsign K3NG ), this Arduino-based keyer is not just a simple device to send "di-dah-dit." It is a feature-packed, contest-grade CW (Continuous Wave) controller that rivals commercial keyers costing hundreds of dollars.

The solves this with a 2N2222A transistor (or BS170 MOSFET) and a 1kΩ base resistor .

A typically shows one or two keying outputs (though the code can support up to six). Each output includes a series‑base resistor and a pull‑up to +5 V on the collector side to ensure a definite high‑impedance state when the output is off. The output jack is usually a mono 3.5 mm plug that connects to the transceiver’s straight‑key input.

If using an LCD (such as a 16x2 or 20x4), I2C displays are preferred to save GPIO pins on the Arduino. Building the K3NG Keyer: Step-by-Step