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Page:Popular Science Monthly Volume 89.djvu/154

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��Popular Scie7we Mo7\thly

���A wireless relay for increasing receiving speed and for relaying to telegraph lines

��Greater Speed in Wireless Receiving

DR. RAY E. HALL, of Portland, Ore., has recently developed an invention that may increase the speed of wireless receiving by automatically recording at an average speed of a little more than one hundred words a minute. On test that speed has been increased to as much as two hundred words a minute. Speed, however, is not the greatest factor in the invention, which is called a wireless relay, for by means of this device messages may be automatically relayed to a wire telegraph line by the same action which records the message. This may easily open up new possibilities for wireless telegraphy, by connecting it directly to the wire system. The relay may also be used for receiving a number of wireless mcsssages at the same time, on the same aerial at the same wave- length. Relayed messages are auto- matically written in ink, on commercial ticker-tape. The ability to receive simultaneously several messages is based on tuning to spark-tone or group-fre- quency instead of to wavelength only. The relay is connected with the wire- less set in place of orilinary telephones. With the device a whole night's work from Sayville, L. L, 1,500 miles away, has been received at the experimental laboratory. The instrument worked alone in a room by itself, since it has attached to it an automatic starting and stopping de\'ice. When the wireless message starts, the very first sound transmitted is placed on record, and

��when the message is ended the tape stops.

A light current of air passing through the box and coil into the cylinder shown in the illustration, is the main element employed in relaying the wire- less signal. Any commercial record or sounder, electric bell or light can be attached to the instrument to record the messages.

Receiving Undamped Oscillations

Arrange a piece of fine iron or steel wire, such as that used for the "E" string of a mandolin, over the pole faces of a small horseshoe electromagnet of the kind used in an ordinary buzzer. Mount a contact-screw directly above the wire where it passes across the magnet faces. Connect the magnets in series with an 8 c. p. lamp on the 60 or 120- cycle alternating-current lighting line, and put the iron wire and contact into your receiving-circuit as shown in the diagram.

The arrangement in the accompany- ing diagram gives a musical note to the signals received from arc or high- frecjuency alternator stations, the pitch depending upon the number of cycles used in the power line. The vibrating wire much be adjusted so that the con- tact makes a clean, sharp break each time the lighting current pulls it down. The tuner and detector must be adjusted in the same way as for receiving spark- stations. High-frequency spark-stations can be heard while the wire-interrupter is running, but the notes of their sparks will be changed.

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��Diagram of a simple receiver for undamped oscillations

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