NF1J NF1J Ham Radio November Foxtrot One Juliet

Morse Code / CW Projects

Build simple CW tools that make practice and operating more fun.

Code practice oscillators, straight key wiring, paddle interfaces, sidetone circuits, CW audio filters, Morse trainers, and practice keys made from shop scraps.

View CW projects Open CW simulator
CPO Practice toneKEY Straight + paddleWPM Trainer
CW Builder Note

Keep it simple and quiet.

A good CW project is reliable, comfortable, and easy to hear. Start with low-voltage audio projects before connecting anything to a transceiver key jack.

  • Use isolated key/PTT wiring when unsure.
  • Keep sidetone volume adjustable.
  • Label tip/ring/sleeve on every plug.

CW Helper

WPM and tone practice helper

Estimate timing for practice and generate Farnsworth-style spacing targets for a training session.

Interactive CW Trainer

Virtual key, live Morse decoder, and listening practice

Click the straight key, use the dit/dah buttons, or press the keyboard. The browser generates the sidetone, so no separate audio files are needed.

Virtual Straight Key

Keyboard shortcuts: . for dit, - for dah, Space for letter gap, / for word gap.

What You Are Sending
Current letter—
Last decoded—
Listening Practice

Play a random character, listen to the dits and dahs, then reveal the answer.

?

Tip: start slow, listen for the rhythm, then raise WPM when letters begin to sound like one complete sound instead of separate dits and dahs.

DIY Project Library

Classic CW builds

Use these cards as practical starter plans. Confirm transceiver key-jack requirements before wiring to a radio.

AUDIO OSCILLATORNF1J CW BENCH

Beginner

Simple code practice oscillator

A battery powered tone box for learning Morse without tying up a transceiver.

Parts555 timer or small audio oscillator, speaker, key jack, 9V battery
  1. Build the oscillator and volume control on perfboard.
  2. Wire the straight key in series with the tone trigger.
  3. Mount the speaker, switch, and jack in a small case.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

TIP + SLEEVENF1J CW BENCH

Keying

Straight key wiring guide

A clean wiring reference for 1/4 inch and 3.5 mm key plugs.

PartsMono plug, shielded cable, strain relief, key terminals
  1. Identify tip and sleeve with a meter.
  2. Wire tip to key contact and sleeve to key ground.
  3. Add strain relief and label the plug.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

DIT / DAHNF1J CW BENCH

Paddles

Paddle interface box

A small adapter box for dual-lever paddles and keyer inputs.

PartsStereo jack, terminal block, shielded cable, enclosure
  1. Map tip/ring/sleeve to dit/dah/common.
  2. Add screw terminals for quick paddle swaps.
  3. Test dit and dah before plugging into the radio.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

SIDETONENF1J CW BENCH

Audio

Adjustable sidetone oscillator

A clean sidetone monitor for homebrew keyers or practice boxes.

PartsAudio oscillator, volume pot, tone pot, speaker or headphone jack
  1. Build the tone oscillator with adjustable pitch.
  2. Add a volume control and headphone output.
  3. Shield the audio wiring if hum appears.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

NARROW FILTERNF1J CW BENCH

Receive

CW audio filter

A simple audio bandpass filter to make CW tones stand out in noisy receive audio.

PartsOp-amp filter module or passive RC parts, audio jacks
  1. Place the filter between receiver audio and headphones.
  2. Tune the center frequency near your sidetone pitch.
  3. Add bypass switch for normal listening.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

MORSE TRAINERNF1J CW BENCH

Microcontroller

Arduino / ESP32 Morse trainer

A small trainer that sends random characters, words, and callsigns to a speaker.

PartsESP32 or Arduino, piezo/speaker, button, display optional
  1. Generate Morse timing in code from WPM.
  2. Add buttons for speed and practice mode.
  3. Save last settings in browser/device storage if desired.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.

SHOP KEYNF1J CW BENCH

Hands-on

Scrap-part practice key

A simple straight key from wood, screws, spring metal, and a knob.

PartsWood base, brass screws, spring strip, knob, rubber feet
  1. Mount a spring strip as the moving lever.
  2. Use screws as adjustable contacts.
  3. Wire to a practice oscillator, not directly to RF power.

Bench test first. Keep radio keying circuits isolated unless your radio manual confirms direct wiring.