US1641635A - Adjustable condenser - Google Patents

Description

R. M. KLEIN ADJUSTABLE c oNDENsER sept. 6, y1927'. l

Filed NOV. l, 1924 BY PM, 5w/Wm may ATTOD NEY5 Ficha@ M /f/@fh -mimmF-gm r Patented Sept. 6, 1927.

RICHARD M. KLEIN, OF NEW YORK, N. Y., SSIGNR T0 F. A. D. ANIGREA, Xiti-C., F YORK, N. Y., A CORPORATION 0F NEW YGRK. l

ADJUSTABLE CONDENSER.

Application led November This invention relates in general to electric systems or circuit arrangements of were signaling systems such cs those described in U. S. Letters Patent to Hitzeltine Nos'. 1,450,080 und 1,489,228, wherein inherent or natural capacity coupling between pnrts or portions thereoic is' neutralized by the proper adjustment ot' u condenser of extremely I small capacity; and has for its object the provision of e condenser of improved de sign particularly applicable to neutralizing undesirable capacity coupling in radio receivers utilizing various types of vacuum tubes ot diiiierentcharacteristics.

'in order to change vacuum tubes ot one type to vacuum tubes -ot another type in indio receiving apparatus which employs neutralization ot capacity coupling, it has heretofore been neccessary to repent the permanent adjustment of the neutralizing condensers by ineens of the somewhatcninber sonic balancing process required at the time when the receiver is first assembled.

The present invention provides e neutrnlizing condenser which may be permencntly adjusted initially to elect the neutnlizution ot thc inherent inter-electrode capacity of various types of tubes, any one ot which only thereafter be used in the saine receiver with the mere requirement of setting tlieneutralizing condenser to the permanent position indicated thereon ns beingl the proper settingpredetermined for n given type oi tube.

A better understanding.;- ot the present invention und :in additional appreciation of its advantages may' be had from e consideration of the following,T description of n preferred cnibodin'ient us illustrated in the uccoinpunying' drawings, in which I Fig.' l represents n plan view of nn ndjustsblc condenser incorporating this invention; i Fig. '2 is e verticalv section taken through line 2-`2 ot' Fig. l; and l Fig. l shows :rcircuit diagram of n cepncity-neutrnlized -tuned odio-frequency :unplitier to which this invention .is especially applicable.

Reterring new to Figs. l and 9. of the drawing: The adjustable condenser is mounted upon nu insulating bese 1 and mcy comprise utubular metallic electrode 2 snrroundingv n tubulnr dielectric il, which may be oi :my suitable dielectric nintcrinl such i, 1924. Serialy No. 'M'il ns or hard rubber, and one, or pret# erebly tirol-inside rod-like electrodes Il sind lt will be observed that the electrode i is not ,fixed as is elecLrode 5, but .it is inov` able and nniy he adjusted axially with reifcrcnce to electrode i). in order to very the dielectric sur'iece included between electrodes t2 and f-i. As represented in the dren ing, electrode 5 is preferably stationery and is secured by e screw to connecting lng; Electrodes -i und 5 are conveiiiently formeel from No. 'le B. & S. gauge copper Wires,v

electrode i being longer and having e nie nipuleting handle Z on its outside end. This handle is so orined 'es to serve es en indicntorS, which niny be set et any desired indicated position 9, such os E or Si marked on base 1. The letter D in this instance represents e, setting or the condenser ivhich will serve to neutralize the inherent interelectrode capacity coupling ot n so celled dry cell. tube in accordance with the disclosure ot the aforementioned. Einzel patents; and, likewise, the letter Si represents the proper .setting neutrniize. the inherent nter-electrode capacity conpling of e fao-celled storage battery tribe. it the capacity of the neutrali.' g condenser vis so chosen relatively to the number or turns Nl' and N2 of coils L1 and L25 Fig. Si, respectively, that the ratio of the inter electrode capacity to be neutralized to the capacity oi the neutrulizii'ig Acondenser is aquel to vlthen the ningneto-motive force ot' Lfc will equal end cancel that of LU provided the coils have the proper relative polin-ity, viz, the terminals connected together niust be of unlike polarity. No voltage will then be induced in either coil, and, therefore, no variation can occur in the grid potentiel due to the variation in the plete potenQ tial, assuming the resistnnces of' the coils negligible in comparison to their reoctences;

Elli

hence the undesirnble etl'ects ott espec-ity 300 coupling will have been eliminated. A vltnll and complete discussion of this method for neutralizing capacity coupling Wiil be found in the Hiizeltine ,patents referred to. lt is,

or course, sometimes desirable to mori: these W5 positions in other Ways, such es by indi eating the vaines et the cnpeciti s directly, or by using on arbitrary scale. Fig. I, illnstretiiig the preferred eniliodiinent, shows the indications inerlred upon the lease of the condenser, but it is frequently convenient to place marks upon the condenser itself, particularly when space does not permit of a scale or other indicating means. In order that any desired adjustment of the condenser may be maintained and an accurate setting held indefinitely, notches 10 have been provided inl electrode 4, into which engages pro]ection ll of a spring Contact member` l2. A screw having a slotted head 13 may be provided to support the electrode l under the pressure of spring l2 so that the electrode may slide longitudinally through the slot. Spring 12 is secured to the base l by a screw f2() and terminates in a connecting lug 14,10 which a connecting wire may be attached. Ordinarily the condenser is con'- nected into its circuit by means of lugs G and 14;, this connection resulting actually in two capacities being connected in series, the first oapacityexisting between electrodes 5 and 2, and the second capacity between electrodes 2 and Il, The resultantcapacity of these two in series may, be varied by n g Asliding intermediate electrode 2 so as to 1nclude more or less dielectric surface between it and the two inside electrodesy and also, asabove described, by sliding electrode et infer out of the dielectric tube 3. lt is preferable, practically, to set the intermediate lelectrode 2 at the time when the lcondenser is first calibrated and `then to lool; that elec- -trode againstr inadvertent movement by means of clamp 17 and screw lo. Lug 1F "is provided to make contact with electrode 2 in case the connection through lug t provides too small a resultant capacity. The dielectric tube 3 is secured against movement by means of a clamp 19 and screw 18,.

At the present time there are on the American market `vacuum tubes, vfor reception purposes, of three general types ranging in grid-plate capacities from about 15 micronfiicrofarads to about 25 micro-microfai-ads. Two'of these types are adapted to be supplied with filament heating current derived from dry cells, and the other type is adapted to Idraw current from storage batteries. lt is thus possible for the owner of a receiver incorporating the-invention described herein to change from dry cell tubes to storage battery tubes with the solo requirement of moving the setting of the neutralizing condensers from position D .to S with the assurance that the receiver will then be correctly neutralized. Since the initial cali-bration and permanent setting of the neutraliz- `ing condensers for the proper and ellicient operation of radio receivers embodying the Hazeltine principle of neutralization of capacity coupling involves the use of an elaborate testing apparatus and skill not to be expected of the general public, it will lbe readily appreciated that the present invention provides an extremely simple means for making feasible the interchange of vacuum tubes of certain definite characteristics in the type of receiver to which this invention is peculiarly adapted.

The wiring diagram of such a receiver is shown in Fig. 3, which represents a radio receiver embodying two stages of timed radiofrequency amplification in which the gridplate coupling capacity of the vacuum tubes A and A1 is neutralized by neutralizing condensers (l, and Cu in cooperation with a winding' of interstage coupling transformers T1 and T2 respectively. A detector tube A: is shown lconnected in the custon'iary manner to the output of transformer TQ, and includes in its plate circuit telephone receivers R. In order to simplify the diagram, the usual audio frequency amplifiers have been omitted from Fig. 3, since it is here desired to illustrate the application of this invention to a radio-frequency amplifying system. rl`he present invention is obviously applicable to other uses, however, such as the neutralization of capacity coupling between coils, lietween portions of various circuits, or between electrodes of vacuum tubes utilized for various other purposes.

I claim:

An electrostatic condenser comprising` two rod-like electrodes. one of said electrodes being movable toward and away from the other for varying` the capacity of the condenser. said movable electrode being provided with a pluralit)r ol" spaced .stops and means oper-- able to engage said stops individually` said means and said stops being operable conjointly to maintain. the selling of the condenser at any one of a plurality of predetermined capacity falues.

In testimony whereof lY aliix my signature.

l? llOHA RD M. KLEIN.

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