. Practical wireless telegraphy; a complete text book for students of radio communication . are shown in Figs. 134 and135. When an alternating currentpasses through the coil, the correspond-ing magnetic lines of force rise and fallwith the current, but the collapse of thefield sets up a counter E. M. F. whichacts as an effective resistance. The flowof current can be Taried by a multi-point switch as in Fig. 134, or by draw-ing the iron core in and out of the windings as in Fig. 135. In the design of Fig. 135 a Ushaped iron core is inserted in two windings connected in series. The self-inductio
. Practical wireless telegraphy; a complete text book for students of radio communication . are shown in Figs. 134 and135. When an alternating currentpasses through the coil, the correspond-ing magnetic lines of force rise and fallwith the current, but the collapse of thefield sets up a counter E. M. F. whichacts as an effective resistance. The flowof current can be Taried by a multi-point switch as in Fig. 134, or by draw-ing the iron core in and out of the windings as in Fig. 135. In the design of Fig. 135 a Ushaped iron core is inserted in two windings connected in series. The self-induction of thecoil is varied by moving the core in and out the windings. Certain types of high potential transformers are designed for direct connection to thepower mains, and therefore they do not require a reactance regulator. 110. Aerial Changeover Switch.—^The object of the aerial switch is toconnect the aerial alternately from the transmitting to the receiving of the potentials of the transmitting apparatus, the receiving apparatus must be completely disconnected from. Fig. 134—Primary Reactance Coil. 3 the transmitting aerial by a switchwith a break of at least 6 inches inlength. An aerial switch of recent design, thetype S. H. switch of the Marconi Companyis indicated in Fig. 136 with the necessarydiagram of connections for a commercialradio installation. When the handle of theswitch is thrown upward, the apparatus isconnected for receiving, but in the down-ward position the transmitting apparatusfunctions. The switch controls several Fig. 135—U Shaped Reactance Coil. ., •_ a i. • -^ ii iU Other important circuits as well as theaerial circuit connection. Thus when the switch is thrown to the transmitting position, (1) Contacts A, B, close the D. C. circuit to the generator field; (2) Contacts C, D, close the circuit to the automatic motor starter or to a motor driven blower; (3) Contacts E, F, close the circuit to the primary winding of the power tr
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
