Don’t trust your memory. The repack should have a table correlating Arduino pin numbers to function. Cross-check this with the k3ng_keyer.ino configuration section (look for #define pin_dit and #define pin_dah ).
A standard repack schematic usually includes these key "pieces": k3ng keyer schematic repack
or shifting from the memory-constrained Arduino Uno/Nano to the more powerful Arduino Mega 2560 Don’t trust your memory
Regulatory and Practical Notes
Jump to the “Inputs” block. The repack shows a 0.1uF capacitor across each paddle switch to debounce (optional but recommended). Paddle left → D3, right → D2. GND is common. galvanic isolation (optocouplers)
: A modern 2023 repack that uses SMD components, galvanic isolation (optocouplers), and a 3D-printed enclosure. SimpleCWKeyer (VE3WMB)