US2045769A

US2045769A - Electrical control circuit

Info

Publication number: US2045769A
Application number: US363761A
Authority: US
Inventors: Geffcken Heinrich Hermann; Richter Hans Rudolf
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1928-05-31
Filing date: 1929-05-17
Publication date: 1936-06-30
Anticipated expiration: 1953-06-30

Description

J1me 3Q, 1936. H. H. GEFFCKEN ET AL, 2,@459769 ELECTRICAL CONTROL CIRCUIT Filed May 17, 1929 a M. @fza Dww la g Patented June 30, .1936 p a 2,1)455'69 umrso STA-res. PATENT DFFI'CET;

Heinrich Hermann Geilcken and Hans Rudolf Richter, Leipzig, Germany, assignors, by mesne assignments, to Radio Corporation of America, New York, N. Y" a corporation of Delaware Application May 17, 1929, Serial No. 363,761

In Germany May 31, 1928 tillaims. (c1. 250-21) This invention relates to an electric control an amplifier with a limiting or critical value, on circuit, more particularly to an amplifying circuit exceeding which a. sudden change 01 current adapted for controlling a mechanical relay or takesplace insuring reliable operation the similar device by a weak current or potential mechanical relay connected with the amplifier.

5 impulse. The invention has special use in segre- In apparatus heretofore known using ordinary 5 gating or sorting systems chosen herein for illusamplifiers in connection with mechanical relays, tration although not limited thereto.- the degree of differentiation of the bodies being It is known that the tuning of a resonant cirtested is determined by the limiting response cuit may be modified by the magnetic or dielecvalue or sensitivity of the mechanical relay.

tric properties of a body by introducing the body With an amplifier constructed and arranged ac- 10 into the electric field of a condenseror into the cording to the present invention on the other 'nagnetic field of a self induction coil inserted in hand, the sensitivity is determined by the limitthe resonant circuit. The extent to which the ing or critical value of the amplifier. Moreover, tuning of the circuit is modified depends on the in thermionic valve relays such a limiting or properties of the body in question. With the ascritical value can be fixed in a much more exact it; sistance of well known devices such as with the and constant manner and is much less aflected aid of a resonance arrangement, it is possible, by outside influences such as moisture, vibrations with the use of amplifiers, to control or operate and the like, than an ordinary electromagnetic relays whenever the change in the tuning of the relay.

resonant circuit, produced by thebody to be A further advantage of the present invention 20 tested, exceeds a given limit. is the possibility of using in most cases a much It is further known that it is possible to prosmaller number of thermionic valves. duce a tightening of the coupling between two In order that the invention may be clearly coils by means of magnetic bodies, by introducing understood and readily carried into effect, the

5 the latter between the coils in question. When some will now be described more fully with referan alternating current passes throughone coil, ence to the accompanying drawing, in which:- an alternating current will also be induced in the Figure 1 is a diagrammatic view of a separating second coil owing to the coupling produced by device in which the invention may be advantathe body to be tested, and with the aid 01' well geously used, and

0 known amplifying devices it is possible to operate Figure 2 illustrates by way of example the con- 0 a mechanical relay by means of the induced altrol and amplifying circuit according to the internating current whenever the coupling provention. duced by the body to be tested exceeds a prede- Referring to Figure 1, the pieces of mineral i termined limit. to be separated, some of which may contain mag- Finally, it is known that a body which is netic material and are to be separated from the 5 brightly illuminated by a lamp and brought in others, fall through the slideway 2 into the hopfront of a device sensitive to light such as a. per 3 and from the latter through the coil 4 photoelectric device, selenium cell or the like, into the separating mechanism. The separating causes an electric current to be produced by the mechanism consists of an electrically operated photoelectric device, the strength of which varies flap valve 5 which is either in the position shown 40 in proportion to the brightness or the color oi the in the drawing in full lines or in the position body in question. With the aid of amplifiers it indicated by dotted lines, and serves to guide the is possible to operate mechanical relays by means pieces of material I into the slideway 5 o h of such an electric current whenever the brightslideway 1 respectively. The coil 4 is part 01' the ness of the body tested is greater or smaller than electric device 8 controlling the electromagnetic 45 a given value. relay 9. The flap valve 5 is normally in the posi- All these well known phenomena have already tion shown in the drawing in full lines, so that been utilized for obtaining an automatic separathe descending pieces of material are guided into tion of materials. In individual cases they have the slideway 6. As soon however as one of. the

also been used for separating rocky minerals into pieces I contains suflicient quantities of mag- 50 difierent groups according to their proportion oi. netite, it will act on the coil 4, and there will be ore content. produced in the device 8 an electric efiect caus- The present invention which may be applied ing response of the relay 9. As soon as the relay with advantage in any of the systems o1 the 9 is operated, the flap 5 will be thrown over into character indicated, consists in the provision of the position shown in dotted lines, and the piece 55 hand plate of the condenser 2 I.

of material in question willbe guided into the slideway I. In this manner all the pieces which do not contain any magnetite, or in which the proportion of magnetite is below a certain limiting value, will be guided into the slideway 0, while the pieces containing a proportion of magnetite above said value will follow the slideway I and will thus be separated from the pieces having a lower magnetite proportion.

Figure 1 is intended merely to be illustrative of the purpose and uses to which the present invention is to be applied. The invention itself relates to a new arrangement and construction of the electric device 8, shown in Figure 2.

Referring to Figure 2, the electric device 0 comprises two coils IO and II and a condenser I2 connected in series with the coil 4. A thermionic valve I3 is arranged in one of the usual oscillating circuit connections to produce undamped oscillations applied through the coil It to the oscillation circuit comprised of the coils 6, Illand I I and the condenser I2. This oscillation circuit is tuned in such a manner that its wave length is somewhat less than that of the undamped oscillations in the generator coil It. When a magnetic body enters the coil 4, the self induction of the latter will be increased; consequently the oscillation circuit 4, I0, II, I2 will come into resonance with the frequency of the valve generator I3, I4 and an oscillating current will begin to flow in the said circuit. The oscillating current is applied through the coil I5 to the grid of a thermionic valve I'l arranged to act as a detector by the provision of a grid leak-grid condenser combination I6 arranged in a known manner. Since the valve I1 is in series with the resistance I8 and since the action of the oscillations on the detector tube I1 increases the internal resistance of the tube, the potential drop across the tube will increase. Instead however of amplifying this increase of potential in the usual manner by means of several thermionic valves to an extent as to enable it to operate or control a relay which then responds or does not respond according to the magnitude of this potential, the increase of voltage is applied according to the present invention to a discharge tube relay constructed to have a critical value, 1. e. a sudden change of its output current takes place if the said value is exceeded, whereby an electromagnetic relay may be operated in a reliable manner. The relay circuit and its function will now be described.

The glow tube I9, resistance 20 and the translating device or relay 9 are connected in series across the current source 22. The condenser 2I is connected to the junction point between the glow tube I9 and series impedance 20. The detector tube H in series with the resistance I 8 is also connected across the source 22 and forms a voltage divider circuit for producing varying positive control impulses to be applied to the left As is understood, any other input circuit may be arranged to supply a positive control impulse. In the example as shown, if oscillating currents are applied to the grid of the tube II, a choking or blocking effect of the tube takes place causing an increased tube impedance resulting in a positive potential rise at the junction point between the anode oi. tube I1 and the resistance I8. As a result, the left hand plate of condenser 2| will temporarily become positive when a controlling impulse occurs, such as caused by an object I (see Fig. 1) con-- taining a predetermined proportion of magnetizable material passing through the coil 4 as described hereinbei'ore. The positive potential at the left hand plate of condenser 2| causes a corresponding negative potential to be set up at the right hand plate of the condenser; or in other words, electrons will accumulate at the right hand plate. The latter are drawn from the space current and the upper electrode of the glow tube, thus temporarily increasing the potential at the upper electrode to a degree sufllcient to cause initiation of a glow discharge through the tube I9. After the discharge through the tube has been started, the condenser 2| will at once be discharged through the tube acting as a leak path and a renewed discharge may be started by a new control impulse, such as by a second object containing sufllcient magnetizable material ail'ecting the input circuit. The impedance 20 is chosen in such a manner that the potential at the junction under normal conditions has a definite value below the sparking potential 01 the tube is so that a discharge is effected only by a control impulse of predetermined minimum intensity. As the amount of the change of potential produced depends on the proportion of magnetite in the piece of material I under testwhich is acting upon the coil as, the question as to whether the piece I is guided into theslideway I or not on the basis oi its contents of magnetite, is determined therefore by the electric critical value which represents the ignition voltage of the glow discharge tube I. As this "electric critical value" is 0! course defined much more accurately than, and cannot be aiiected by any exterior influences (moisture, vibrations, rust and the like) to the same extent as the mechanical limiting responsive value at which an electromagnetic relay becomes operative, a device according to the present invention will work in a much more accurate and consistent manner than devices heretofore known for this purpose.

Many modifications so far as actual details are concerned may of course be made in carrying out the present invention within the limits of its essential principle. Thus, the glow discharge tube Il may be replaced by a thermionic valve arranged in a condition or sudden discontinuity to provide similar electric trigger action to a gaseous glow tube as described. Further, in place of the critical voltage there could also be used critical conditions or limits as regards frequency or phase such as are encountered in coupled oscillation circuits.

What we claim and desire to secure by Letters Patent 0! the United States is:-

1. In combination, an electric gas discharge device having a pair of electrodes; an impedance and a source of current; said gas discharge device, said impedance and said source being in series; the potential at the junction point between said gas discharge device and said impedance being normally insuflicient to eflect an ionic discharge through said device; an electrical condenser having one plate thereot connected to said junction point: means for applying controlling potential impulses oi momentary duration and of predetermined intensity to the remaining plate of said condenser to vary the potential of said junction point to such an extent as to eilect a discharge through said device; a translating device; and means for operating said translating device from the output of said gas discharge device.

2. In combination, an electric gas discharge tube having a pair oi. electrodes therein; an impedance; a translating device and a source of current; said discharge tube, said impedance, said translating device and said source being in series with the positive pole of said source being connected to said impedance; the potential at said junction point being normally too low to cause an ionic discharge through said tube; an electric condenser having one plate thereof connected to said junction point; means for applying a positive control potential impulse of momentary duration and of predetermined intensity to the remaining plate of said condenser to produce a positive potential rise at said junction point to effect a discharge through said tube and operate said translating device.

3. In a control circuit, a discharge device adapted to undergo a sudden discontinuous change of impedance when subjected to a predetermined critical terminal potential; an impedance and a source of current, said device, said impedance and said source forming substantially a series circuit; the potential at the junction point between said device and said impedance being normally below said critical potential; an electric condenser having one plate thereof connected to said junction point; means for applying a positive controlling potential impulse to the remaining plate of said condenser to change the potential at said junction point to a value equal to or beyond said critical potential to initiate the change oi impedance of said device.

4. In a control circuit, an ionic device having a pair of electrodes; an impedance and a source oi. current, said device, said impedance and said source being connected to form substantially a series circuit with said impedance connected to the positive pole of said source; the potential at the junction point between said device and said impedance being normally close to the critical point at which an ionic discharge is produced through said device; an electrical condenser having one plate thereof connected to said junction point; and means for applying a positive control potential impulse to the remaining plate of said condenser to increase the potential at said junction point and initiate a discharge through said 20 device.

HEINRICH HERMANN GEFFCEEN. HANS RUDOLF RICHTER.