The Morse code tree: any text turned into sound
The whole alphabet on one drawing. Type anything — your callsign, a word, a phrase — and watch how it would go out on the air. The sound is synthesised in the tab; nothing is downloaded and nothing is sent anywhere.
The board
To the left is a dot, to the right a dash. Beside each track is a silkscreen mark: a circle for one time unit, a bar for three.
The diameter of a pad is the frequency of that letter in English text. That is why E and T are the largest and sit straight under the root, while Q, J and Z are small and lie on the fourth level. The digits are one level below the letters, because they are longer than any of them. The empty outlines are nodes the English alphabet does not use.
Press any pad to hear that letter on its own.
Morse tree
The track to the left is a dot, the one to the right a dash; beside each is a silkscreen mark: · one time unit, ▬ three. The diameter of a pad is the frequency of that letter in English text. Press any letter to hear it on its own. Empty pads are nodes the English alphabet does not use. The bottom row is the digits: they are longer than any letter and so sit a level deeper.
How long it lasts
the same transmission in time: 117 units, 9,4 s at 15 WPM. It shows what the tree does not — a dash costs three times what a dot costs — and that is exactly why «optimality» here is measured in time rather than in the number of symbols.
read back: —
The timing diagram
The second drawing shows what the tree does not: a dash costs three times what a dot costs. The depth of a node and the cost of a letter are different things, and O (---) on the third level takes longer than H (....) on the fourth.
That is exactly why «optimality» in CW is measured in time rather than in the number of symbols. How close the assignment of codes comes to the optimum, and why it is not a Huffman code, is taken apart in «The Morse tree: a variable-length code a century before Huffman».
What not to use this for
Reading off the tree while receiving. Running a finger down the branches while the transmission is in your headphones puts counting where hearing should be: heard → counted → recalled. That intermediate step hits a ceiling of about ten words a minute, and unlearning it later is harder than learning it properly from scratch.
The tree is a good answer to «how does this work» and a poor answer to «how do I learn it». Learning takes two other things: the characters at 20–25 WPM from the outset with stretched gaps (the Koch method with Farnsworth spacing), and knowing the structure of a contact — which is in the neighbouring tool.