US2000986A - Rectifier and filter circuit - Google Patents

Description

y 1935- R. RECHNITZER 2,000,986

RECTIFIER AND FILTER CIRCUIT Filed May 25, 1929 INVENTOR R. RECHNITZER 7L; ATTORNEY Patented May 14, 1935 UNITED, STATES RECTIFIER AND FILTER CIRCUIT Rudolf Rechnitzer, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic in. b. H., Berlin, Germany, a corporation of Germany Application May 25, 1929, Serial No. 365,843 In Germany July 4, 1928 2 Claims.

The present invention relates to electrical rectifying and filtering systems, and more particularly to such a system having means for neutralizing the effect of alternating current com- 5 ponent on a utilizing circuit.

Whenever thermionic tubes are fed from a supply network with direct current potential by way 01' a filter arrangement, care must be taken so that the harmful influence of potential fluctuations upon the operation of the tubes will be entirely precluded. The aim therefore is to provide filter circuits constructed in such a way that all alternating current fluctuations or ripples superposed upon the direct current will be completely eliminated.

An arrangement which utilizes the filter circuit idea is illustrated in the drawing. The potential derived from an alternating current network n, n, is changed by means of a thermionic rectifier it into a pulsating direct current potential, and the latter is rid of superposed alternating current components by the aid of a suitable number of condensers Cl-C4 and resistances Wl-Wl, plate potential being then derivable across the output terminals a and b for the audion and amplifier tubes to be connected therewith. The filaments and the ground are united with terminal .0, while the grid is con nected with terminal d for the supply of a negative biasing potential.

In order that alternating current components may be precluded from the plate potential, the filter chain must be designed with great care. If the desired high constancy of the plate potential is obtained, care must be taken so that also the grid biasing potential will be as invariable as feasible, and this, as is well known, is obtainable by means of a potential divider connected with resistance WI and comprising a condenser Cl and a very high resistance W2. If the alternating current resistance of the condenser Cl amounts, say, to several ohms and that of resistance W2 to several hundred thousand or millions of ohms, then the alternating current component arising across the terminals of resistance WI will be absorbed by resistance W2, with the result that the condenser C4 connected between the filament and the grid will be practically free from alternating current potentials.

Now, the filter arrangement hereinbefore referred to does not always supply direct current potentials perfectly free from fluctuations, so that it must comprise several filter sections it complete purification or the potential is to be insured, and this means a correspondingly high cost for the outfit.

It has been suggested in the prior art to feed thermionic tubes with a plate potential by way of a rectifier, said plate potential consisting of 5 a direct current potential having more or less marked alternating current components superposed thereon, while the undesirable effect of fluctuating alternating current potential is to be compensated by that the grid is at the same time 10 supplied with fluctuations acting in the same sense, these compensating grid potentials being derived from a resistance passed by the alternating current component by way of a convenient potential divider.

Now, the present invention has as its basic feature a device which will insure all of the desirable features of the two methods hereinbefore described, while the resistance whose fall of potential is to be employed to furnish the compensating grid fluctuations consists of the same resistance which is used and required any way for the production of the negative grid direct current bias. In this way it is not necessary to dimension the filter chain so as to insure complete purification of the direct current potential. If the plate potential fluctuations are not entirely eliminated, it is sufiicient according to the present invention to choose the resistance WI and the potential divider C4, W2 united therewith in such a way that the grid potential fluctuations required for compensating the plate potential fluctuations will just arise at the necessary phase across the terminals of condenser C4. The resistance whose fall of potential furnishes the necessary compensating potential to the grid may be contained either in the first mesh of the filter chain, as shown, or else in some other mesh.

What I claim is:

1. In an electrical rectifying and filtering system, the combination of a source of alternating current energy, a rectifier coupled thereto for the production of unidirectional current energy, a filter system having its input side connected to said rectifier for reducing the ripple component of said unidirectional current, a utilizing circuit coupled to the output side of said filter system, and additional means comprising a resistance and a condenser in parallel for coupling said filter system to said utilizing circuit for substantially neutralizing the remaining ripple component of said unidirectional current.

2. In an electrical rectifying and filtering system, the combination of a source of alternating 55 current energy, a rectifier coupled thereto for the production of unidirectional current energy, a filter system connected to said rectifier for reducing the ripple component of said unidirectional current and a utilizing circuit coupled to said filter system, additional means for coupling said filter system to said utilizing circuit for substantially neutralizing the remaining ripple component of said unidirectional current, said last named means comprising a resistive element and a capacitive element in series shunted across an input terminal and an output terminal of said filter system, and a connection between the common point of said two elements and said utilizing circuit.

RUDOLF RECHNITZER.

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