Ultraschallsender

"Wherever possible in Elektor circuits, transistors and diodes are simply marked `TUP` TDD TDD (Transistor, Universal PNP), `TUN` (Transistor, Universal NPN), `DUG` (Diode, Universal Germaniuml or `DUS` (Diode, Universal Silicon). DUD DUD- This indicates that a large group of similar devices can be used, provided they meet the minimum specifications listed in tables 1a and DU5 1b. For further information, see the article `TUPTUN- DUG-DUS` in Elektor 1, p. 9."