US2261667A - Electrical resistance - Google Patents

Description

NOV. 4, 1941. w STRQSZECK 2,261,667

ELECTRICAL RESISTANCE Filed Dec. 28, 1959 ffy,

WITNESSES:

v v INVENTOR /f//z/M WARNEY Patented Nov. 4, 1941 UNITED STATES PATENT OFFICE ELECTRICAL RESISTANCE Application December 28, 1939, Serial No. 311,360 In Germany February 22, 1939 (Cl. B01-63) 3 Claims.

My invention relates to variable electrical resistances and more particularly to balancing resistors for electrical meters, indicating instruments, and the like.

In order to properly adjust the circuits of the measuring systems in certain electrical instruments, it is customary to provide adjustable balancing resistors. The prior art teaches the use of such resistors consisting of resistance Wire formed into a loop or spiral with a short circuit clamp slidable along the loop to vary the resistance between the terminals. This construction offers diiiiculties in that for higher resistance values the loops must be constructed of comparatively thin wire which is particularly susceptible to fault or breakage. Although the use of longer and thicker wire decreases the liability of such failure, the space required for mounting becomes unduly large in many cases.

According to my invention, the above disadvantages are overcome by providing a resistance member comprising a plurality of parallel paths, one or more of which may be broken during the balancing operation to secure the proper resistance value. In a specific embodiment of my invention, one or more bridging conductors are welded or soldered to the resistance element at points which are preferably uniformly spaced from each other and the balancing accomplished by breaking the bridging conductor at individual points.

It is, accordingly, an object of my invention to provide a resistance member, the resistance of which may be readily changed by changing its shape through a convenient operation.

Another object of my invention is to provide a novel and improved variable resistor to serve as a balancing member in an electrical instrument.

Other objects of my invention will become evident from the following detailed description taken in conjunction with the accompanying drawing, in which:

Figure 1 is a plan view of one form of resistor built in accordance with the present invention; and

Figs. 2 to 5 inclusive, are similar views of modiications thereof.

In Figure 1, a wave-shaped resistance wire I, with a terminal 2 at each end, has a bridging conductor 3 soldered or welded to its individual turns as at 4. The bridging conductor is preferably of some conducting material such as copper. It will be readily seen that the adjusting or balancing of the resistance of the unit may be carried out by cutting through the conductor 3 at any desired points such as indicated at 5.

In Fig. 2 a second bridging conductor 6 is soldered to the other ends of the turns in the resistance wire I, as at the points l. Since this structure is otherwise the same as that of Fig. l, the same reference characters are applied to the same parts in the two figures. This conductor 6 is preferably of thinner wire than the other conductor 3, or else of a material of lower conductivity as, for example, nickel. In this embodiment, more delicate adjustment may be obtained since the bridging conductor 6 may also be cut at various points between turns of the resistance Wire I.

A straight resistance wire II is employed in the embodiment of Fig. 3 and a conductor I3 of wave-shape is connected to it at various points I4 between the terminals I2. Cutting the conductor I3 alfords convenient means for changing the resistance of the unit.

The resistance wire 2| in Fig. 4 is formed into a loop between the terminals 22, and rung-like bridging conductors 23 are soldered thereto as at 24. In this case, the adjusting or balancing is accomplished `by cutting through the desired number of conductors 23.

Obviously the bridging members shown in Figs. 1 through 4 may be made of the same material as the resistance member. In Fig. 5 is shown a gridshaped member of sheet resistance material 3| which may be cut as at points 33 in any combination required to give the desired resistance between the terminals 32.

It will be readily realized that the present invention provides a balancing resistor which, although capable of a wide range of resistance and conveniently adjustable, requires only a small space for even comparatively high resistance values.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. An adjustable electrical resistor comprising resistance means formed into a wave shape consisting of turns of substantially equal amplitude over at least a portion of its length and arranged to be connected across a source of electrical potential, a first conducting means electrically interconnecting a group of corresponding points of at least a portion of said turns, and a second conducting means electrically interconnecting a different group of corresponding points of at least a portion of said turns, said second conducting means having a different electrical conductivity per unit length than said first conducting means, and each of said conducting means being readily severable between selected interconnected points on said resistance means.

2. An electrical resistor comprising resistance material formed into a Wave shape, a first conducting strip interconnecting the peaks of the respective loops of resistance material on one side of the axis thereof, and a second conducting strip having a conductivity dierent from that of said rst strip interconnecting the peaks of the respective loops on the other side of said axis, said conducting strips being selectively severable between adjacent loops independently of said red sistance material to adjust the resistance of the resistor.

3. An electrical resistor comprising a continuous electrical resistance member formed into substantially a Wave shape and adapted to be permanently connected between a pair of terminals, a pair of conductor strips having diierent values of conductivity, and means connecting said conductor strips to said resistance member to interconnect adjacent peaks of the loops thereof on each side of its axis, said conducting strips being of a material which is readily severable between selected adjacent resistance loops to adjust the overall resistance Value of the resistor.

WILHELM STROSZECK.

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