Skip to content
Morse UniverseMorse Universe

Morse code practice oscillator

Send morse on a straight key or iambic paddles and hear it as you go. It reads back what you sent and shows your dahs and gaps against true timing.

Hold the key for as long as each mark lasts. On a keyboard, press it once, then hold the space bar.

It read

How to use it

  1. Pick Straight key or Paddles, and the speed you want to send at.
  2. Hold the key on the screen, or press it once and use the keyboard: the space bar for a straight key, the [ and ] keys for paddles. You hear a tone while each mark sounds.
  3. Read what it heard, then look at the timing rows: any figure more than a fifth off true timing shows in orange.

Free sending reads everything since you last pressed Clear. Send this shows a letter or a word and tells you whether it read right, then moves on. If you have a lesson saved in the Koch trainer, its letters are the ones you get, so you send what you've learned to hear; otherwise you get A to Z. The words come from Edward Dolch's list of common words, up to 5 letters long.

What the timing shows

ITU-R M.1677-1 times morse in units of one dit. The practice oscillator measures your sending against your own dit, so a hand that sends every mark a little long still reads true ratios. It draws your last word as you sent it, with the same word at true timing under it.

A dit, the short mark
1 dit
A dah, the long mark
3 dits
The gap between the marks of a letter
1 dit
The gap between letters
3 dits
The gap between words
7 dits

Your speed comes from the same dit. Speed in words per minute (WPM) is timed on the word PARIS, 50 units long, so one dit lasts 1,200 milliseconds divided by the WPM: 80 milliseconds at 15 WPM. A gap far longer than a word gap counts as a pause, not spacing, and is left out.

Straight key or paddles

A straight key sounds for as long as you hold it down, so you time every mark and every gap yourself. The speed buttons only tell the practice oscillator where to start reading; after a few letters with both dits and dahs, it follows your own speed.

With paddles, a keyer times the marks at the speed you pick. Hold the left paddle for a row of dits, or the right one for dahs. Squeeze both to alternate them, which sends a C as dah dit dah ditwithout a separate press for each mark.

The keyer here works in iambic mode B, as the WB4VVF Accu-keyer did: let go of both paddles during a squeeze and it sends one more mark of the other kind. To send that C in mode B, let go after the second dah; in mode A, the original Curtis keyer chip's mode, you'd hold on until the last dit.

Questions

What is a morse code practice oscillator?

A small tone generator you plug a key into, so you hear a tone while the key is down and can practice sending without a radio. This page does the same in your browser, and reads back what you sent.

Is there a free morse code keyer online?

Yes: pick Paddles on this page. It is free, needs no account, and runs in your browser on a phone or a computer.

Should I learn on a straight key or a paddle?

Either works. On a straight key you time every dit and dah yourself; with paddles the keyer times the marks, and you time the gaps between letters and words.

What is the difference between iambic mode A and B?

It is what the keyer does when you let go of both paddles during a squeeze: mode A finishes the mark it is sending, and mode B sends one more of the other mark. The keyer on this page uses mode B.

How do you send morse code by tapping?

Make each dah three times as long as a dit, and leave a gap of one dit inside a letter, three between letters and seven between words. Read how to keep the timing when you tap.

More morse tools

Sources