Apparatus or circuits for sending one or a restricted number of signals, e.g. distress signals

Full Title

Apparatus or local circuits for transmitting or receiving dot-and-dash codes, e.g. Morse code (teaching apparatus therefor G09B; telegraph tapping keys H01H21/86) > Apparatus or circuits at the transmitting end > Apparatus or circuits for sending one or a restricted number of signals, e.g. distress signals