Learn how to make - TELEGRAPHIC APPARATUS Excerpt from the book: Things To Make by Archibald William Published - 1918 The easily made but practical apparatus described in this chapter supplies an incentive for learning the Morse telegraphic code, which is used for sending sound signals, and for visible signals transmitted by means of flags, lamps, and heliograph mirrors. Signalling is so interesting, and on occasion can be so useful, that no apology is needed for introducing signalling apparatus into this book. The apparatus in question is a double-instrument outfit, which enables an operator at either end of the line to cause a "buzzer" or "tapper" to work at the other end when he depresses a key and closes an electric circuit. Each unit consists of three main parts— (1) the transmitting key; (2) the receiving buzzer or tapper; (3) the electric battery. The principles of an installation are shown in Fig. 33. One unit only is illustrated, but, as the ot...
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