388 



THE WORLD'S ADVANCE 



keys of the primary and secondary cir- 

 cuits are pressed. When the primary 

 "In" key is pressed the primary spools 

 rotate so that the copper ribbon winds 

 from the companion spool on to the ac- 

 tive spool of the tuner. On the other 

 hand, the pressing of the "Out" key 

 causes the ribbon to unwind from the 

 active spool on to the companion spool. 

 The same procedure is observed in ad- 

 justing the secondary of the tuner. The 

 tuning, obviously, is exceedingly sharp, 

 since a fraction of an inch of ribbon can 

 be reached by this method. Further- 

 more, the motor drives the spools at a 

 fairly high rate and to wind the ribbon 

 from one spool to the other is but a 

 moment's work. 



There are two loading coils used in 

 this receiving set, one for the primary 

 and the other for the secondary of the 

 inductive tuner. These coils are wound 

 on a flat spool and have taps taken off 

 at certain intervals and connected with 

 the contact points of switches. Over the 

 contact points slide switch arms which 

 are operated by a pair of electro-magnets 

 through a ratchet movement. To cut in 

 or out the loading inductance in the pri- 

 mary or secondary, the same sets of keys 

 the second and third couples as were 

 employed to operate the winding on the 

 primary and secondary spools, are 

 pressed. However, in this instance, one 

 of the keys of the first group is pressed, 

 operating as a "shift key," to use the 

 expression of the inventor. By pressing 

 the shift key the differentiation is made 



A Partial Rear View of the Set: The Black Inductive 



Tuner Spools may be Seen, as well as the White 



Spool of the Loading Coils. 



so that the switches are operated instead 

 of the winding. The "In" keys adjust 

 the primary or secondary loading coil 

 switches ; the "Out" keys adjust the same 

 switches in the reverse direction. The 

 reason for the shift key is that it saves 

 at least four extra keys, the addition of 

 which would unduly complicate the ma- 

 nipulation of the receiving set. Mr. 

 Goodchild states that a separate shift 

 key in the form of a long bar will be 

 used in the future. 



The last four keys are used in con- 

 trolling the condensers in the primary 

 and secondary circuits. Each condenser 

 consists of a large number of brass 

 sheets separated by a special insulating 

 fabric. Brass rods passing through holes 

 bored in the plates serve to short circuit 

 more or less of the condenser, thus vary- 

 ing the capacity in circuit. A small mo- 

 tor operates each condenser, cutting in 

 more or less plates until the required 

 capacity is attained. 



The automatic receiving set is quite 

 simple to operate. It is claimed by its 

 inventor that within twelve seconds ev- 

 ery tuning operation can be performed 

 throughout its scope. The first step in 

 tuning is to press the "In" coupling but- 

 ton so as to bring the coupler spools close 

 together. The loading coil switches are 

 then adjusted, followed by a closer ad- 

 justment by means of the ribbon wind- 

 ings. Finally, the sharpest tuning is 

 sought by adjusting the primary and sec- 

 ondary condensers. The operator can 

 then make the coupling looser if he so 

 desires. 



By the introduction of a keyboard the 

 operation of a receiving set is greatly 

 simplified, for, after once learning the 

 different functions of the buttons, any 

 one can receive signals without having 

 to master the action in back of each but- 

 ton. Dials are provided on the different 

 parts of the set so that an operator can 

 pick up any station at any time by know- 

 ing the necessary adjustments of the dif- 

 ferent parts. 



The motive power is supplied by a 

 twelve-volt motor operating from a stor- 

 age battery. The two condensers each 

 have individual motors that draw their 

 supply from the same battery as the main 

 motor. The various pairs of electro- 



