Elias tapped the left paddle. A perfectly formed dit rang out through the speaker.
+-----------------------+ | Arduino Nano / Uno | | | [Dit Paddle] ------->| D2 (Interrupt pin) | [Dah Paddle] ------->| D5 | [Command Button] ---->| D11 | [Speed Potentiometer]| A0 | | | | D13 (PWM) |---> [Audio Amp / Speaker] | D10 (TX) |---> [Rig Keying Circuit] +-----------------------+ Pin Assignment Reference (Standard Arduino Nano Config) Speed Potentiometer (Wiper pin) D2: Dit Paddle Input D5: Dah Paddle Input D10: Transmitter Keying Output (PTT/Key) D11: Command Button Input D13: Sidetone Audio Output 4. Detailed Circuit Breakdown k3ng keyer schematic
Download the code repository from the . Open the keyer_features_and_options.h file. Elias tapped the left paddle
This wasn't just a switch; it was a safety barrier. The schematic was telling him: "Do not connect the delicate 5-volt microcontroller directly to a 300-volt tube rig. Use the optocoupler, or you will fry your board." Detailed Circuit Breakdown Download the code repository from
The K3NG firmware generates a sidetone square wave on a digital pin (usually D6 or D9 via PWM). However, a raw square wave is harsh and weak. The schematic typically includes:
At its simplest, the K3NG keyer can be built on a breadboard with just an Arduino, a couple of resistors for the two paddles, and a few transistors for the keying output. This "core" circuit is ideal for those who just want a no-frills iambic keyer with the excellent "CMOS Super Keyer" timing.