US2197507A - Electric oscillatory circuits - Google Patents

Description

ELECTRIC OSCILLATORY CIRCUITS Filed Sept. 14, 1937 ffy f f/g. 2

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Patented Apr. 16, 1940 UNITE SES PATENT orticaN ELECTRIC osciLLA'ronY CIRCUITS Application September 14, 1937, Serial No. 163,799 In Germany September 5, 1936 2 Claims.

As is well known, oscillatory circuits coupled in any manner to an oscillatory system will change their natural frequency whenever the coupling is varied. In most cases tuning corrections must 6 then be made by hand in order to give the circuits the previous frequency. This is of special `disadvantage if receivers for wireless telephony and telegraphy are concerned. Here the coupling of the circuits is variable in most cases in 10 order to provide for changing loudness and selectivity. For instance, if here a station already adjusted as regards coupling is to be readjusted with a View to increasing its separation capability then at the same time the tuning knob must be 15 actuated in order to compensate for the detuning caused by varying the coupling.

The invention shows how to avoid such detuning. In accordance with the invention this result is attained by an automatic correction. In ar- 15 rangements as provided by the invention any variation of the coupling entails a variation of the self-inductance or capacity of the oscillatory circuit, the arrangement being such that the detuning of the oscillatory circuit is compensated by an opposing detuning.

The possibilities of carrying out the invention are extremely numerous, as will be understood from the following description, reference being 25 had to the accompanying drawing in which Fig. 1 is a Wiring diagram showing the usual arrangementof an inductive coupling, and Fig. 2 is a diagram illustrating the fundamental conception of the invention as applied to an inductive a coupling.

By moving coil l away from coil 2, Fig. 1, the resultant inductivity of the coil 2 is increased, thus requiring a manual readjustment if, after the coupling-variation thus eiected, the oscillatory circuit is to have the saine frequency as (Cl. Tis-44) before. 3 denotes the capacity of the oscillatory circuit.

In the arrangement shown in Fig. 2 the selfinductance of the oscillatory circuit comprises two coils 4, 5 connected in series. Coil 5 is` smaller 5 than coil 4. In accordance with the invention any variation of the coupling, that is, any movement imparted to coil I causes the coupling eiective between coils 5 and 4 to be varied likewise. In order to perform this the coils il, 5 may be 10 arranged to form a variometer which is turned b-y a leverage or some other suitable means whenever co-il l is moved, or coil 4 may be wound onto coil i, whereby the same eect as before is obtained with the aid of still simpler means. Equally, it is possible, for instance, to provide for turning a small auxiliary condenser connected in parallel with the tuning condenser 3.

What is claimed is:

1. In an oscillatory circuit comprising a sel- 15 inductance and a capacity and coupled solely by an adjustable inductive coupler to an oscillatory system, the method of avoiding this circuit being detuned on adjusting this coupling, which method consists in simultaneously and automatically producing a continuous detuning of opposing character to that consequent upon a continuous adjustment of the coupling.

2. An oscillatory circuit arrangement comprising an oscillatory circuit including a main coupling coil connected in series with an auxiliary coupling coil and a tuning condenser, another main coupling coil on to which the first main coupling coil is wound, and means to vary the displacement of sai-d main coils with respect to said auxiliary coil whereby detuning of said oscillatory circuit is continuously compensated for during continuous displacement of said main coupling coils with respect to said auxiliary coil.

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