| United States Patent Office.
Elmer E. Butcher, of Interlaken, New Jersey. Assignor to Marconi Wireless Telegraph Company of America, a corporation of New Jersey. Means for Receiving Electrical Oscillations. | ||
| No. 1,233,841. | Specification of Letters Patent. | Patented July 17, 1917. |
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Application filed May 12, 1914. Serial No. 837,988. | ||
To all whom it may concern:
Be it known that I, Elmer E. Butcher, a citizen of the United States, and a resident of Interlaken, in the county of Monmouth, State of New Jersey, have invented certain new and useful Improvements in Means for Receiving Electrical Oscillations, of which the following is a specification.
The general object of my invention is to provide simple means by which signals produced by electrical oscillations may be made audible, and whereby they may be considerably amplified.
My invention may be applied to the detection of any electrical oscillations, no matter how produced, and may be used in connection with systems for wireless or wire telegraphy or wireless or wire telephony. One of the uses in which my invention finds utility is the detection of continuous or undamped oscillations at the receiving end of a wireless telegraph system, although this is not the only use to which it may be put.
I accomplish the object of my invention by providing means whereby one or more of the constants of one of the circuits at the receiving end of the system may be periodically and progressively varied, so as to put this circuit into and out of a condition of resonance with the received oscillations.
I shall illustrate and describe my improved receiving means in connection with a system in which continuous or undamped oscillations are used, and in which the constant that is varied is the capacity of the circuit, although it will be understood that the inductance may be varied to secure the same effects, or both the capacity and inductance may be periodically increased and decreased.
In the drawings accompanying this specification I have shown in Figure 1 the receiving end of a wireless telegraph system, using undamped oscillations, embodying my invention. In Figs. 2 and 3 I have shown modifications thereof. In Fig. 4 I have shown a form of condenser I may use, and in Fig. 5 I have shown the method of applying this condenser to circuits in which damped oscillations have been received, so that they may be used for the reception of either damped or undamped oscillations.
Referring to Fig. 1, 1 is the aerial; 2 is the aerial tuning inductance and the primary of an oscillation transformer; 3 is a variable condenser; the aerial is earthed at 4, as usual. The secondary of the oscillation transformer is shown at 5, the coupling being preferably a loose one. Connected to the secondary of the oscillation transformer are a revolving condenser 8 and an indicating instrument such as a telephone, 6, which latter is preferably shunted by a variable condenser 7. The revolving condenser is driven by a motor or other suitable source of power 9.
The construction of the revolving condenser may be seen in Fig. 4, Fig. 4a being a sectional view, and Fig. 4b an end view thereof. The revolving condenser consists essentially of a frame 10 supporting a plurality of stationary plates 11, as shown in Fig. 4b. Interleaved between the stationary plates are revolving plates 12, which are mounted upon the shaft 13 of the motor 9. It will be apparent that, as the revolving plates rotate, the capacity of the condenser increases to a maximum and decreases to a minimum, periodically. These are any suitable shape, but are preferably so formed as to give a constant increment of capacity for a constant rate of rotation.
If, therefore, the inductance 5 and the capacity 7 be adjusted to certain values, the secondary circuit will be in resonance with the aerial circuit for a given position or value of capacity of the revolving condenser 8, and if the condenser be revolved by means of the motor 9, the secondary circuit will be thrown into and out of resonance with the aerial circuit as of ten as the plates of the revolving condenser pass to a given position.
It is this method of operation that I make use of in detecting signals. The undamped oscillations received are, of course, of such a periodicity that they are beyond the upper limit of audibility and produce no audible signals; by by so adjusting the constants of the secondary circuit that the rotation of the revolving condenser periodically throws the secondary circuit into and out of resonance with the aerial circuit, and audible signal of a frequency proportional to the speed of rotation of the condenser is produced.
In using my improved apparatus the aerial circuit may be as usual, tuned to the wave length of the incoming oscillations. With the revolving condenser stationary, I