SU34653A1 - Device for measuring weak currents - Google Patents

Description

The proposed device for measuring weak currents is based on the already known comparison method, according to which the test and reference current sources are connected in series in a closed circuit, and the indicator is connected in parallel to the terminals of the current sources. According to the invention, a galvanic cell is used as a reference current source in the device, one of the electrodes of which is made movable relative to the second fixed electrode to change the internal resistance of the cell.

In FIG. 1 shows a device diagram; FIG. 2 - a general perspective view of the device; FIG. 3 - axial section of the galvanic element; FIG. 4- its cross section; FIG. 5 is a section through the top of the element, and FIG. b - view from above of the micrometer screw controlling the movement of the straight electrode.

The galvanic cell is made in the form of a cylindrical hollow electrode electrode 8, filled with a weak solution of sodium chloride, and a second movable electrode 18 made of a porous tree impregnated with solution of zinc chloride. The electrode is located inside the cylindrical wooden vessel of the vessel 9 and fastened with it by a coupling 7 /.

(439);

A thin rubber bag Yu, filled with the same electrolyte as electrode 8, is placed between the electrode and the inner walls of the vessel 9. The IT coupling is made of electrically conductive material and serves simultaneously with the wire 12 to connect the electrode 8 with the clip 13. The upper end of the electrode is tight is closed with a stopper 14 made of an insulating material, having in the middle holes for the TOHKOiy wire 16 supporting the metal holder 17 of the second electrode 18, On the electrode 18, as indicated earlier, made of solution-impregnated chloride a porous wood zinc fortified metal tip 19 bearing on the end bead 20 of wax wire 16 is connected to terminal 21 ,. mounted on the end of the ruler 5, driven in the guide cylinder 2 by means of the micrometer screw 4. The screw 4 is provided with a disk 6 with divisions, by means of which. and a fixed index 23, it is possible to measure the immersion depth of the electrode 18. The disk 6 can be calibrated directly in terms of the current strength.

With a micrometer screw fastened current interrupter, made for example in the form of a cylinder 26 of insulating material (Fig. 6) carrying contact plates, alternately behind

“The contacts that are not shown in the drawing, opening and closing during the rotation of the screw 4, and, consequently, when raising or lowering the moving electrode J8; these contacts of the chopper are included in the indicator circuit 7, for example, a telephone connected, as already indicated at the beginning of the description, parallel to the terminals of the sources of the reference -8 J8 current source and 27 under study 27 (Fig. 1).

By implementing such a connection scheme and rotating the screw 4, the immersion of the electrode J8, and thus the internal resistance of the element 8, J8, is adjusted until the current in their circuit is zero; This moment will be marked by a complete lack of sound in the phone.

The current strength of the current source under investigation is determined on a scale awarded at 6.

The carbon cylinder and the gue rod impregnated with a solution are the most accurate pair in an electrolyte consisting of a highly dilute solution of sodium chloride (one crystal per 250 grams is distilled. Water.) According to the author, such a combination is suitable for currents with a force of 10. For pain, strong currents, coal and iron, corroded with sodium chloride, can be used as electrolyte.

The outer cylinder can be made of copper, with an inner surface treated with monobasic phosphate soda and zinc chloride or iron, steel, tin. For weaker currents, silver, nickel, etc. can be used.

If necessary, the liquid electrolyte can be replaced by a hard, flexible medium (frozen gelatin, rolled-up cardboard treated with the same electrolyte); In these cases, metal electrodes are used, and some pretreatment of the material used for the electrolyte and other dimensions of the lower part of the device are required. For a more accurate readout, various devices already known can be used in the device, for example, a nonius, or, as such, a disk b can be used provided that it is coarsely read along line 5,

.The determination of the moment when the current in the phone passes through zero can be replaced by an automatic recording by transferring the oscillation of the telephone membrane to a recording lever or other device.

The subject matter of the invention.

Claims (3)

1. A device for measuring weak currents by the method of comparison by which the test and reference current sources are included. In series, the detector is connected in parallel to the terminals of the current sources, characterized in that a galvanic cell is used as a reference current source, one of the electrodes of which, in order to change the internal resistance of the cell, is made ps the relative second fixed electrode. 2. The form of the device according to claim 1, characterized in that the galvanic cell is made in the form of a cylindrical carbon electrode 8 filled with a weakly sodium chloride solution, and the second movable electrode J8 made of porous wood impregnated with zinc chloride solution, provided at the immersed end with a metal tip 20 . 3. In the device according to claim 1 and 2, use a rotating chopper connected to the indicator circuit and directly connected with the moving moving electrode mechanism in order to periodically close the indicator circuit of the telephone while gradually dipping or lifting the electrode. FIG