US1647659A - Transmitter circuit - Google Patents

Description

H. PAUl-l TRANSMITTER CIRCUIT Filed Auz. 12. 1926 2 Sheets-Sheet 1 p Observed animaba CurveI GurvolI '04-40-30 2o -lo o lo 2o :so 4o no w' *Pgr Nav. 1, 1927. 1,647,659 H. PAUL1 A TRANSMITTER CIRCUIT Filed 111111.12. 192e 2 Sheets-sheet 2 Passes Nev; 1,1921. 1,647,659

UNITED .STATES PATENT OFFICE.Y

HEINRICH Panni, E EEEEIN, GERMANY, AssrGNoE rro s'iEiuENs a HaiesxE Ax'riEN- GESELLSCHAFT, or siEiuENssrAD'r, NEAR BERLIN, GERMANY, a eEniraNcomrm.

TRANSMITTER GIRGUIT.Y Application illed August 12, 1926, Serial No. 128,878, and in Germany August 12, 1925.

.'The invention relates to an adjustment rent and the pressure can be obtained by 55 between a transmitter and a consumer desuitably adjusting the constants of these two vice, on which it acts (ohmic resistance prireciprocal values representing the magnitude mary winding of a repeater), and the object of the resistances. l

is to transform without' distortion into elec- Withiiithe limits of the beforementioned tric currents, the pressure variations acting approximation, the relationship between r 60 on the transmitter diaphragm (sound and p can be represented by a function hav-- waves). ing the form:

Figures 1 and 2 are curves relating to the A 1o invention while Figure a iuustretes the eir- (r-R) (riesig-:0; cuit. 65

In an article on transmitters (Elektrowhere R and P are the @o ordinates of th technik and MaSChQeIlbeu, 1925, N0 13, middle point M, and a=MS is half the large page 239) R. Kelch glves QarbOn tiaIlSIIllttel axis of the equilateral hyperbola. R also curves for the current 1n relationshlp t0 represents the value ofthe resistance, which the pressure p on .the diaphragm, the bataccording t0 the approximate hyperbola, 70 tery pressure V being steady. If the relavvould correspond to an infinitely great restionship of the transmitter resistance T to Sure p on the diaphragm (See Fig 2) ence the pressure p be ascertained from these within the range of this approximation,

curves, 1t will be found that the function proximates very closely to one branch of an P "P Y elullatefal I lyebola h avlng lts asymptotes If the transmitter bellocate'd in series with Pamueuy dlSPlCed Wlth respect t0 the? rec' the battery V and the consuming resistance tangular co-ordinate system 1', p. In Figure Ra, then he current s 1 the dotted line represents the curve for 80 r=f p obtained by xeiehs tests, while the V V full line curve is a branch of an equilateral Rl+r Ra +R +0 hyperbola, which `approximates to the relap- F tionship between fl' and p when p=0 nearly. The approximate h erbola curves .ob

The example shows that this approximation is very good for many positive and nega-tive gdlyalglyglfl bglstllgrpraxiez values of p. It is often found to be a defective feature gllsvgspa cgil'tfuhat 1s to Say R has 35 of the resistance transmitter that the sinoidal variations of its resistance cause not only al oagslteealrlibbldtilii atil ilieitdiis tflzigtresli: 9

5 e ternating currents of the same frequency,but ance, on which the transmltter works, 1s

as:strattataastratte: ,ses wvluehof s essere 4o the relationship between resistance and curalsll a' magmtu e t al a rent is reciprocal value. But in reality it is y of little importance whether the variations V P in the resistance give rise to distortionless "'='(P )y transmitter currents; but it is important that 45 the current shall closely correspond to the and the Pressu-re Variation A P have corre variations in pressure on the diaphragm of SPOnding current Variations the transmitter effected by the sound waves. V This result can be closely achieved by mak- A'IFAP; ing use, of the beforementioned 4fact that 50 there isa reciprocal relationship between the that is to say the variations in the, current V pressure on the diaphragm and the resistbecome proportional to the pressure varia- 10b ance of the transmitter. The following retions. 1 marks will show how a linear, that is to say This holds good for the pressure varia- .y distortionless, relationship between the curtions within the range of the approximate ance, on which the transmitter Works. Let

the voltage of the battery 11 be represented' ing tension across Ra is obtained when Ra=R, and

e RaAi= (lUgAp 144.530 4.5 volts.

' Ihe direct current transmitter current then 1s J=g(P) 111.1 X 10-a amps.

Hence very considerable undistorted amplitudes of current can be obtained by adjusting the 'consuming resistance according to the invention.

In order to effect an adjustment in a transmitter circuit according to the invention, it is first necessary to make tests to iind the relationship between the transmitter resistance r and the pressure p on the diaphragm for a number of positive and negative values of p in the neighbourhood of 29:0. The constants R, P and C for the equilateral hyperbola which best approximates the tested relationship of the 1, p values in the neighborhood of p=0 then have to be determined, preferably, by calculation. The resistance Ra, on which the transmitter Works, is then selected, according to the invention,

so that it equals the absolute value (negative) R, which has been found according to the above method.

What is claimed is:

In a circuit arrangement for transmitters, a transmitter whose resistance varies with the pressure on the diaphragm according to a hyperbolic function, said hyperbolic function approximating, for small positive and negative values of pressure, an equilateral hyperbola whose asymptote corresponding to infinite pressure is displaced on the resistance axis of co-ordinatesin a negative direction from the corresponding` asym tote of the first mentioned hyperbola, and a oad, having a resistance equal to the difference in the resistance ordinates between said two asymptotes, connected to the transmitter' whereby increments in pressure cause proportional increments 1n current.

In witness whereof, I hereunto subscribeA of July A. D., 1926'.

Images