US2100458A - Electrical circuit with modulating or rectifying devices - Google Patents

Description

Nov. 30, 1937. H. WALTER 2,100,458

ELECTRICAL CIRCUIT WITH MODULATING OR RECTIFYING DEVICES Filed May 18, 1934 C a i I i g I i I d l I E INVENTOR HA/VS W417i? BY g M ATTORNEY Patented Nov. 30, 1937 i V I r UNITED T -S PATENT PFFW ELECTRICAL CIRCUIT MTIICMODUIKTING V on. RECTIFYING DEVICES Hans Walter, Berlin-Siemensstadt, Germany, as signer to Siemens & Halske, Aktiengesellschaft, Siemensstadt, near Berlin, {Germany a corporation of Germany 1 Application May 18, 1934', Serial N6,- 7263 Q In Germany May 18,1933 1 Claims. 7 (Cl. 250-21) v r 7 This' invention relates to electrical cir- The corresponding relation between the resultcuits which include modulating or rectifying 'deing currenti and tl re voltage u -is given day the vices. Itisapparent that distortionless modulaexpression r v tion or rectification would result, if a rectilinear 5 relation between input current and output volt- V 7 age existed in' the modulator or rectifier. From Equations 1) and 2 and t well Such an ideal condition has never been produced k n l w o :Kifghhofl the mcints p 5; in known modulating or rectifying circuits. are Seen to be i I Moreover, departing from this relation in the L operation of vacuum or gas filled tubes, aswell (3 1q= "(Gp.-i qa) V ,1

as in rectifiers of the dry cell type,such as copper .l V V y oxide rectifiers in circuits known heretofore proi ib v .1. duces distorting harmonics in the output of the G rectifier or modulator. V 1 G l 252 5 1' 7 A One object of the invention is to increase the (5) -(E i po-weroutput without increasing distortion. -Anv V other-object is to decrease distortion Without de- GG+GP+.*-1Sthevcqnductancebetweenlhe 7 creasing power'output. 'Still anotherobject is to mifi gg g gggfigg f zgg igg' fi Y approach an ideal modulating or rectifying device. the resulting conductance; G is so djmensiohed j laresent s is b-asledfllfthe that the Equation (2) contains no terms or third ow e' ge: 'In mo ula ing or. rec i ying' circui s i I combined with resistances in parallel or series mm -m t o the expressmn arrangement the ccefiicientofthe third harmonic V 4 g of" the equation giving the relation between the (6) 7d instantaneous values of applied voltage'and re- 25 a a It is-to beseen that suitable dimensioning-of 811117111 current in b re resented b an e uav tion h aving l ositiiie arid n egative terr n s. In 'acthe resigances combined with rectifier the: cofdance with the present invention it isproposed dlstomon occun'mg fmm .t m to overcome the disadvantages of the known may f d q ea gior yelmnnated. By corremodulatingor rectifying devicesby' such a dispondmggdlfnensmflmg @180 the Q E t 3 3omensioning of'the resistances combined with the n e f t utstead of'the 'thlrdharmomcs' modulator'or rectifier, that the coefficient of the T1115 deneilslon 5 lmpfortam? for detect9r third orhigher harmonicsis zero. meiaurmg p 1. Whlchvthe h a The invention mayrnow e more fully under monies do not generate direct currentand are stood by reference to the following description, therefore Q e I when .read inconnection with the accompanying The Equatwn (6) canals) bgsatlsfied wlthout drawing, Figure .1 of which illustrates an :electhe P e the riara'uel't'eslstance is' i trical rectifying circuit and Figure 2 of which posslbleitqsatlsfithlsiequatlonfinlylbyesultable: shows a curve of .a know'n rectifying device of the dimension of the resistance combined in S i 40 dry cell type such as copper. oxide. v h f n modulating g rePtifyiPg device" 40' In Figure 1 R0 isarectifier with the alternatomlttimg; e? 9 3 9? combined w h ing current resistance R0. The rectifier R0 in the rectifier G follows for h '5 j series with a resistance of the conductance Gv is conductancerthe'expresslon connected with a source of electromotive force, I

the voltage of which is u. A resistance of the V e conductance G is connected in parallel with the TbereforefromEqu-atlon the'relaitmn rectifier. The voltage across the parallel resistdamensioq ofltherconductancefif the Senes ance is designated with us. 'The relation between slstances y the equation- 77 r the current id and the voltage as is determined 52 by :physical .qualitiesof'the rectifier and maybe t=- d g 59 v expressed by theequation 1 2 3 The characteristic of a rectifier device 'with dry (1) cells (comprising e. g. a metallicqnemberjsuch (a 6 7,; are coefficients, characterizing the as a copper-or iron plate having a coating ofgea 55 qualtities of the rectifier.) V V compound such'as anoxide of themetalformed 55' i directly thereon) can be given approximately by the following exponential function:

(Cr represents the rectifying constant of the rectifier, R0 represents the algebraic sum of the .By inserting these three coemcients in Equation (7) we get the expression as the characteristic equation for the elimination of the third harmonics.

According to the invention the resistance combined in series with themodulating or rectifying devices is so chosen, that its value is the half of the alternating current resistance of the rectifier or modulator. V

The resistance being so dimensioned the power output can be increased. The increasing of the power output is restricted by the generating of fourth harmonics of inadmissible value. Practically the invention permits increase of the power outputwhile distortion is held within the same value as is usual in circuits not dimensioned according to the, present invention. The invention permits the distortion to be diminished if the power output is maintained at the same value as in circuits not arranged in accordance with the present invention.

The derivation of the equations referred to above was made without considering the capacity of the modulating or rectifying device. Above a certain frequency this capacity varies the resulting equations.

The capacitance of the rectifier ought tobe con sidered, if it cannot be neglected compared with the alternating current resistance R0. According to another idea of the present invention the influenceof the rectifier capacity is decreased to such. a small degree that it may be neglected. For this purpose the alternating current resistance R0 of. the modulating or rectifying device is decreased by a suitable biasing potential from a source B connected as shown. The usual choke coil D may be included in the biasing circuit to prevent the alternating current from reaching the biasing source. This automatically causes the upper cut-off frequency of the rectifier to increase. Figure 2 shows the relation between the current i and the voltage e of a copper oxide rectifier of normal construction. The slope of this curve for a certain voltage is proportional to the reciprocal of the resistance R0 for this voltage. It is apparent that at the point B of the curve the current varies in a greater degree when voltage varies than at the point A. It Will be seen, that the alternating current resistance R0 of the modulating or rectifying devices decreases substantially by increasing of the biasing potential.

'pendance has a large value.

By moving the point on the resistance in series with B and changing the biasing potential of the rectifier the upper cut-off frequency of the circuit can be adjusted to the value required.

Another object of the present invention is to compensate for the dependence on temperature of the alternating current resistance. It is known, that for copper oxide rectifiers this de- The alternating current resistance change amounts to 40 per cent (when temperature increases 10%). According to the invention the biasing potential is always so regulated that the alternating current of the rectifier always has the same suitable value.

The regulating of the rectifier or modulator resistance in accordance with the invention is not restricted to the compensation for undesired bine a suitable number of rectifiers in parallel.

Compared with this method the present invention causes a substantial reducing of means. In the scope of the invention it is possible, to regulate automaticaly the biasing potential with means well known to those skilled in the art.

It will be obvious that the general principles herein disclosed may be embodied in many other forms different from those illustrated, without departing from the spirit of the invention as defined in the following claims.

What is claimed is:

1. In an electrical circuit, a rectifying device, a resistance in series with said device, means for applying alternating current wave energy to said device and resistance, and a second resistance in parallel with said device, said resistances being so dimensioned that the conductance of the resistance in parallel with said rectifying device is practically null with respect to the applied alternating current and the conductance Gv of the resistance connected in series with said rectifying device with respect to said applied alternating current is determined by the expression wherein d [3.1, 7. denote the coefiicients of the current-voltage id, ud characteristic a= aa+I dd +'Yaa'+ of the rectifying device.

2. In an electrical circuit, a translating device having a substantially exponential voltage ampere characteristic, means for applying alternating current wave energy thereto, a resistance in series with said device, said resistance having a conductance 1 wherein we. Ba, 1.; denote the coefiicient of the current-voltage 1'4, u characteristic of the translating device.

3. An electrical circuit as recited in claim 2 in The known method;

which said translating device is a rectifier of the copper oxide type.

4. An electrical circuit as recited in claim 2 in which an adjustable source of potential is connected in shunt with said translating device, whereby the ratio between the resistance of the translating device and the capacity of the translating device may be adjusted when the frequency of the applied alternating current is changed.

5. In an electrical circuit, a rectifying device, a resistance in series with said device, means for applying alternating current wave energy to said rectifying device and resistance, and a second resistance having a value such that wherein Old, Ba, 74, denote the coefficients of the current voltage i id characteristic 1 i a=ada+I dd +'Yaa of the rectifying device.

HANS WALTER.

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