US962017A - Electrical apparatus. - Google Patents

Description

R. A. FBSSENDEN.

ELECTRICAL APPARATUS. APPLIUATION FILED 23.18, 1906.

962,017., Patented June 21,1910.'

BEGINALD IA. FESSENDEN, OF IBRANT ROCK, IMASSACIIUSTTS,

nnncraronr. nrrannrtrs.

Specification of Letters Patent- Patented June 21, 1910.

Application ledApril 18, 1906. Serial No. 312,520,

To all whom 'it may concern:

Be it known that I, REGINALD A. FnssnN- DEN, a citizen of the United States, residing at Brant Rock, in the State of Massachusetts, have invented certain new and useful Im rovements in Electrical-Apparatus, of

' Whlch the following is a specification.

The invention comprises certain improvements in current-operated devices, which are especially ada ted for use in connection with currents of hlgh frequency such as are employed in the transmission of energy by kelectro-magnetic waves. y

The invention is' herelnafter more fully described and claimed.

In the accompanying drawings, forming a part of this specification, Figure l is a diagrammatic view illustrative of va form of my invention; and Figs. 2, 3 and 4`are similar views illustrating other embodiments of the improvement.

Many electrical-indicating instruments were wound with coarse wire and formed of coils of large diameter, such, for example, as the tangent galvanometer. Later,Lord Kelvinand others constructed instruments having greatly increased sensibility by-winding the coils oit' much iuer wire and using a larger number .of turns. The rlhomson galvanometer was an example of such 1mproved instrument. The limit was, however, reached in this direct-ion, on account of the high resistance of the wire and the fact that increasing the number of turns brought the outside turns so far away from the core or axis that they produced no good eli'ect.

l have found it possible by making a radical change in the construction of currentoperated instruments to obtain a very large increase in sensibility. rlhis change involves abandoning the large diameter of the coil used by Kelvin and others, by constructing my coils of what mi ht be called microscopic and microbaric imensions, since as a rule they are best wound under a microscope. As illustrating the radical change eected by my improvement, the coil of a Thomson galvanometer is usually about four inches in diameter and .one inch in thickness, whereas .a suitable size of coil for what I call my micro instrument is about four .one-hundredths of an inch in diameter and one one-hundredth of an inch in thickness. The relative volumesjof the coils are in the ratio .of onel to one million. These coils not only furnish very suitable instruments for ordinary uses, but lare especially and peculiarly adapted to signalin by electro-magnetic waves, for the `reason. t at these microscopic coils concen.

trate the magneticefects to such a great degree that the opposition to the current due to self-induction 1s considerably greater than the opposition to the current due to ohmic resist-ance, and hence the coils act very eiliciently and are capable of sharp tuning.

As an illustration of the enormous advantages to be gained by the use of coils of these y extremely tine 'laminated iron wire cores 1n these coils, the laminated iron wire being preferably about one one-thousandth of an inch in diameter, or such thatten of them twisted together will form the thickness of a human hair. v

An additional advantage is obtained where the coil itself forms one of the moving members of a' current-operated device. If such a microbaric coil be attracted by another similar coil, it is found that the amount of movement taking lace in a given time decreases with a very igh ower of the diameter of the wire used, an halving the sizeJ of the wire the movement taking place in a given time may be increased more than one hundred times.

ln the construction shown in Fig. l, the aerial indicated at l is grounded'` at 2.

Micro coils 3 and 4, preferably supported Iso as to be adjustable, are operatively conone end with smallcores l1 and 12 formed elo that by of soft iron or nichel-wire, ahdfpr'eferabl consisting of about fifty pieces o wire ea of about one one-thousandth of an inch in diameter. The coils 3 and 4 are preferably wound with wire one one-thousandth of an inch in diameterv so as to have about fty lacquer, or cellulose. At their opposite ends the needles 7 and 8 are preferablyA provided with line platinum iridium contacts 13 and 14, between which is arranged a wedge 15 preferably of similar material and a apted to be adjusted by a screw 16. A local 'circuit is formed by the battery 17 and indicating e mechanism 18, the wires 5 and 6, needles 7 and 8, and wedge or contact 15.

In the operation of this apparatus the lthe screws 9 and 10 are turned 4until the natural periods of vibration of the needles 7 and 8 carried by said wires are equal, and

.preferably equal to the group-frequency of the signals which it is desired to receive.,

The contact piece 15 is then .adjusted so las nearly to make contact with the points 13 and 14 carried bythe needles. Thecoils 3 and 4 are adjusted to such osition as to produce a maximum effect on oth the movable cores 11 and 12. A fixed core may also be used for increasing the s ensitiveness of the device as arranged in Fig. 2. 'The receiver, consisting o f the micro-coils 3 and 4, may be tuned in any of the usual ways practiced in the art, as, for example, by a variable condenser 19.A

Should any mechanical vibration disturb the receiver, both needles 7 and 8 will move in the same direction, and hence only one of them will make contact with the wedge l5, and the local circuit will not be closed. When, however, waves strike the aerial 1, the currents produced in the micro-coils 3 and 4 will attract the movable cores 11 and 12, causing both contacts 13 and 14 to bear against the wedge 15 and so close the local circuit containing the indicating mechanism 17.

When desired, any suitable arrangement of the contacts and circuits may be used, uch, for example, as that indicated in Fig.

As indicated at 37 in Fig. 1, a mirror may be employed forindicating signals in lieu of the local circuit, such mirror be' attached to one or the other of the nec es 7 and 8.

In Fig. 2, vmy improvement is shown applied to a telephone indicating mechanism. A micro-coil l23, as shown in section and preferably made as above described, is secured to the telephone diaphragm 22 and is connected to the aerial 1. Another microcoil 26 i's seeured to a mount 27 and is cohnected to the coil 23, and also to round, as shown. The mount 27 is adjuste by means of a screw or other suitable means so as to bring the coils 23 and 26 in the most effective relation to each other. When the eurrent is generated b the action of electromagnetic waves of t e aerial, the coils 23 an '26 will attract each other, causing the diaphragm to move, thereby producing a sound.

In the construction shown in Fig. 3 for simllar purposes, the coils 29 and 30 are secured to diaphragms 31 and 32, (the diaphragm 32 being1 similar to a telephone diaphragm, while t e other diaphragm is made sufficiently heavy to prevent moyement of vthe coil attached thereto) arranged in a resonator-tube'34, said tube being provided 'with a istonadjustable by a screw 35, so as yto pro uce resonance to any desired groupfrequency.' In this construction, the removable core is omitted and the fixed coil, which may have a fixed core, preferably projecting into the movable coil, acts on the movable coil, which is preferably smaller than thel fixed coil. The tube is provided with a phonographic ear-piece 36, which may be mserted in the ear as is customary in using these devices, and loss of sound thereby revented. As shown in Fig. 4, a plurality of micro-coils 38 may be used, said coils being arranged in pairs. In the construction, the needles 39 are secured to a common wire 40, which is placed under tension, asin the construction shown in Fig. 1, and are provided attheir ends with cores 42 arranged in operative Arelation to the coils. As an indicating' device, I emplo a minute capillary glass tube 43 secure 'to the wire 40, ysaid tube being provided ar its end with small pieces of mirror 44. Such an ar-9 rangement of mirrors, if given suicient illumination, is ca able of resolving to the same extent as a arge mirror. The effect of any lack of` arallelism in the small mirrors 1s remov by any of the well-known arrangements of prisms or mirrors. A local circuit adjustable in stre may be used in conjunction with this orm of cur- `rent-responsive device and gives greater ease ,l

i ity. Such local of adjustment and sensib circuit is shown in F' 4, where 45 is alocal source of current an 46 adjustable resistance.

It is characteristic of my invention that I employ a microbaric coil, z. e.-a coil of vsmall wireso wound as to produce a relatively high magnetic concentration for a 'ven current, a given llliifthof wire, an a given mass, as com a with coils ordinarily used for electrica instruments. That is, 1n my claims the terms microbaric coil large coetlicient of induction per unit mass, and high intensity of magnetic induction per aorr unit mass and unit of entrent, mean these quantities are of high order of magnitude compared with coils now in use, as in U. S. Patents 711,445 of Oct. 14th, 1902 and 711,184 (see p. 3, line 104).

, ing an indication comprising a coil of such small dimensions as to give the coil a ratio of magnetic induction per unit of mass of the order of 100,000..

3. Electrically actuated means for producing an indication, comprising a coil having a high magnetic concentration and a co-eiiicient of magnetic inductance per unit of mass greater than 100,000.

4. Electrically actuated means for producing an indication comprising amovable indicating member and a coil 1n operative relation to said movable member, having high co-eicient of magnetic inductance per unit of mass e. e., a ratio of self inductance fo mass `of more than 100,000.

5. Electrically actuated means for producing an indication comprising a coil having a ratio of self-induction to mass, greater than 100,000, a movable element, controlling a of which one is attache local circuit, and means in the local circuit p for producing an indication.

6. A receiver for electro-ma etic waves comprising two relativel mova le elements, to a coil having a large co-eiicient of magnetic induction per unit of mass of the order 100,000.

7. A 'receiver for electro-magnetic waves comprising a microbaric coil and` a movable core therefor and indicating means operated by the motion of the core.

8. A receiver for wireless telegraphy comprising a solenoid of which the coil is o f minute relative dimensions having high magnetic concentration per unit of mass and per turn so as to respond to signals, substantially as described.

9. A receiver for wireless signaling comprising several relatively movable members, an indicating device attached to onevof said members, and onevof said members includin a microbaric coil of minute dimensions, o the order of magnitude of .001 of an inch for the wire, whereby high magnetic concentration suiicientto respond to electro-magnetic oscillations is obtained.

In testimony whereof, I set my hand.

REGINALD A. FESSENDEN.

lVitnesses:

Roar. S. KEARNEY, DARWIN S. WoLco'r'r.

have hereunto

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