US2035034A - Amplifying stethoscope - Google Patents

Description

March 24, 1936. J. WEINSTEIN 2,035,034

AMPLIFYING STETHOSCOPE Filed Feb. 2, 1935 Ema/whoa; Joseph 14 641252 e-Ln Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE AMPLIFYING STETHOSCOPE Joseph We'instein, Brooklyn, 'N. Y.

Application February 2, 1935, Serial No. 4,697

1 Claim. (01. 179171) This invention relates to electrically amplifynected by conductors 32 and 33 with the respecing stethoscopes such as are shown in my prior tive conductors 28 and 30, the resistance 29 and Patent No. 1,976,707 of October 9, 1934 and more condenser 3| being thus connected in parallel beespecially relates to improvements in the circuits tween the cathode 25 and ground l8.

5 and arrangements of parts shown and described A conductor 34 connects the plate 24 with one in the aforesaid patent end of a choke coil 35 having its other end conone important object of th i v nti i t nected by a conductor 36 with a ground 31 through improve the sensitivity of devices of this char a condenser 38. The choke coil has a grounded acter. core '39 and forms what is termed an audio choke.

A second important object of the invention is A l megohm resistance Winding s O e end 10 to provide, in such a device, a simple and eflicient Connected to the COIldllCtOl 34 y a uctor 4| volume control for uch stethoscopes and its other end connected to the COIldllCtOl 36,

A third important object of the invention is to between the condenser 38 and Coil by a conprovide a separate choke 11 for t utput of ductor 42. The audio chock 35 and resistance 15 Such instruments. 40 are thus connected in parallel between the 15 A fourth important object of the invention is plate 24 and ground t provide an improved amplifying Stethoscope Movable over the windings of the resistance 40 wherein amplification will be effected without the is a Contact 43 Which is Connected by a conductor use of a tra fo m 44 with a 0.2 microfarad condenser 45. At 46 is With the above and other objects in view, the avacuum tubehaving grid ap 8 e de 20 invention consists in general of certain novel by a pail of parallel connected grids a a hode circuit arrangements and combinations of details 50 carrying a fourth grid- 5| anda heater fi ament hereinafter n described and claimed, one 52. The condenser 45 is connected by a conductor bodiment of the circuits and apparatus used be- 53 with the grid The Conductor 53 0011- ing illustrated in the accompanying drawing, nected by a'conductor 54 with'one end a 500 25 wherein: megohm resistance 55 having its other end con- The figure is a Wiring diagram of the Complete nected by a conductor 56 with a ground 57. device The cathode 50 is connected by a conductor 58 In the embodiment of the invention shown in with a 5 megohm resistance 59 having its other the accompanying drawing there is provided a end connected by a conductor 60 to the ground combined stethoscopic sound receiver and micro- Wire A l microfarad Condenser is phcne or microphonic Stethoscope m from which nected by a conductor 62 with the conductor 58 leads a cable H of the usual two wire type, one and conductor 63 with the ground wire wire being connected to a contact l2 and the other the reslstance 55 and Condenser being thus Wire being connected to a Contact W A Shield connected in parallel between the cathode and 35 I4 surrounds at least a portion of the cable adjaground T grids 49 are connected by cent the contacts, the latter being supported by ductor 64 h Source 65 of 221/2 volt current Said Shield A jack having Spring contacts '5 and a 0.5 microfarad condenser 66 is bridged and I5 is provided to receive the contacts l2 and across between t Conductors 52 and 40 I3 so that they engage respectively with the said The plate. 4815 connected by a conductor 61 4O jack Contact? A conductor leads from the and a 0.5 ml'crofarad condenser 68. A conductor contact I5 to a ground I8 and a conductor l9 leads 69 the cpndtlctor 67 with one end of a from the contact [6 through a 1 megohm resistchoke C011 havlpg Its other end connected by ance 20 and is connected to the ground wire H. qonducmr H Wlth one end of a 20 megohm Also a conductor 2 I 18 a C15 from the Contact '6 to resistance 72. The other end of the resistance 12 45 the g 22 of a Vacuum tube 23 which also Com is connected by a conductor 13 to the conductor tains a plate 24, a cathode 25 and a heater fila- 36 between condenser 38 and c011 35 $0 that ment 26. The conductor 2| is preferably covered the 0011 m 15 grounded through the -reS1stan-ce r b h M 21 12 and condenser 38. The choke 0011 has its as y a s 1e core 14 grounded and forms an audio ch ke f F The cathode 25 is connected by a conductor 28 t t 45 O or )0 with one terminal of a 10 megohm resistance 29 At is a third vacuum tube having a grid which in turn has its remaining terminal con- 16, plate 77, cathode I8 and heater filament l9. nected through a conductor 30 with the ground A conductor connects the condenser 68 with ()0 Wire 11. A 1 microfarad condenser 3| is conthe grid 16 and t s nduc s n t d by 55 a conductor 8! with one end of a 500 megohm resistance 82 having its other end grounded through a conductor 83. The cathode 18 is connected by a conductor 84 with one end of a 2 megohm resistance 85 having its other end connected by a conductor 86 with the ground wire 83. A 1 microfarad condenser 81 is connected. by a conductor 88 with the conductor 84 and by a conductor 89 with the conductor 86 so that the resistance 85 and condenser 81 are connected in parallel between the cathode l8 and the ground. The plate 71 is connected by a conductor 96 with a 0.5 microfarad condenser 9|, this condenser being connected by a conductor 92 with an output terminal 93. The other output terminal 94 is connected by a conductor 95 with the conductor 88. A 30 Henry choke coil 96 has one end connected to the conductor 90 by a conductor 97 and its other end connected by a conductor 98 to the positive terminal 99 of a connection for volt current. The negative terminal for this current is grounded through a conductor Ifll.

Six volt heater terminals I02 are connected by conductors l3 to the heater filaments of the several tubes so that such filaments are connected in multiple.

In use, the microphonic stethoscope is applied to a portion of the anatomy over the organ to be auscultated, one or more sets of telephone ear pieces having been connected to the cut put terminals. Then the sound impulses emanating from the organ are translated into electrical impulses through the action of the microphone, amplified by the amplifier, and received through the ear pieces as amplified sounds. Obviously a loud speaker device may be connected to the out-put terminals if desired and, when arranged in this manner, the apparatus may be used for clinical demonstrations.

It will be observed that adjustment of the contact 43 along the resistance 40 controls the input to the grid of the second tube and thereby controls the volume delivered to the output terminals of the device. By this means faint sounds may be amplified to clearness while loud sounds may have their amplification restricted so as not to be unpleasant to the auditor.

There has thus been provided a simple and efficient device of the kind described and for the purpose specified.

It is obvious that changes may be made in the arrangement of the parts without departing from the spirit of the invention. It is not, therefore, desired to confine the invention to the exact arrangement here shown, but it is desired to include all such as come within the scope of the appended claim.

What is claimed is:-

An amplifying instrument for microphonic stethoscope circuits comprising in-put terminals, a set of three electronic vacuum tubes each having a grid, a plate, a cathode and a heater element, the middle tube of said set further having a pair of grids between which the plate of said tube is located, a conductive connection between one of said terminals and the grid of the first tube, a ground connection from the other terminal, a resistance bridged between said terminals, a conductive connection having a resistance therein and connecting the cathode of the first tube to the ground, a condenser bridged between the terminals of the last resistance, a choke coil and a third resistance conductively connected in multiple to the plate of the first tube and connected to the ground through a second condenser, a connection from the grid of the second tube to the third resistance through a condenser and arranged for variable connection to said third resistance, a resistance providing ground connected to the last connection between the grid and condenser of said last connection, a resistance providing ground for the cathode of the second tube and having a condenser bridged around the resistance therein, a conductive power input connection for said pair of grids, a condenser bridged between said power input connection and the ground from the second cathode, a connection between the plate of the second tube and the grid of the third tube, a choke coil having one terminal conductively connected to the plate of the second tube and its other terminal connected conductively to the second condenser through a resistance, a conductive ground connection for the grid of the third tube including a resistance, a conductive ground connection for the cathode of the third tube and having a condenser bridged around its resistance, an output terminal conductively connected to the last connection between the cathode and its grounding resistance, a second out-put terminal, a connection between the plate of the third tube and the second output terminal, a choke coil having one end conductively connected to the last plate and its other end conductively connected to the corresponding end of the second choke coil, a power in-put con.- nection supplying current to said plates through said choke coils, and a heater circuit for said heaters.

JOSEPH WEINSTEIN.

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