DE318010C

DE318010C -

Info

Publication number: DE318010C
Application number: DENDAT318010D
Authority: DE
Publication date: 1900-01-01

Description

In der drahtlosen Telegraphic werden viele Detektoren benutzt, die dazu dienen, die Ströme hoher Frequenz in den Schwingungskreisen der Empfangsstation zum Ansprechen zu bringen. Entsprechend der. fortschreitenden ■ Entwicklung auf diesem Gebiete hat man immer mehr danach gestrebt, einen Detektor zu erfinden, der äußerst hohe und gleichzeitig unveränderliche Empfindlichkeit besitzt. Dieses Streben hat unter anderem zur Herstellung der sogenannten Kristalldetektoren geleitet, .bei welchen eine leitende Spitze' 0. dgl. gegen die Oberfläche eines unipolare Leitungsfähigkeit besitzenden Kristalles angedrückt gehalten wird.In wireless telegraphics, many detectors are used that serve to detect the High-frequency currents in the oscillating circuits of the receiving station to respond bring to. According to the. progressive ■ development in this area striving more and more to invent a detector that is extremely high and at the same time has invariable sensitivity. This pursuit has among other things to manufacture the so-called crystal detectors, .which a conductive tip '0. like. Against the surface of a crystal possessing unipolar conductivity held down will.

Ein Beispiel eines derartigen Detektors zeigt Fig. ι. der Zeichnung.An example of such a detector is shown in FIG. the drawing.

ι ist ein Kristallstückchen und 2 eine Schraube, die mit ihrer Spitze gegen dasι is a piece of crystal and 2 is a screw, the tip of which is against the

ao Kristallstückchen drückt. Die Schraube 2 wird von einer Metallstütze 3 getragen, die an einer isolierenden Unterlage 4 befestigt ist, welche außerdem eine Metallplatte 5 trägt, an der das Kristallstückchen festgelötet ist.ao pushes crystal pieces. The screw 2 is carried by a metal support 3 which is attached to an insulating base 4, which also carries a metal plate 5, to which the piece of crystal is soldered.

Leitungsdrähte 6, 7 sind z. B. in Klemmen 8 bzw. 9 der Metallplatte 5 bzw. der Stütze 3 befestigt. Dieser Detektor besitzt den Vorteil, daß er sehr empfindlich ist, gleichzeitig aber den Nachteil, daß schon die geringste Verschiebung des Kontaktpunktes zwischen der Schraube 2 und dem Kristallstückchen weitgehende Empfindlichkeitsänderungen des Detektors herbeiführen kann. Die Gründe dieser Mangelhaftigkeit des Detektors ergeben sich aus folgendem.Lead wires 6, 7 are, for. B. in terminals 8 or 9 of the metal plate 5 or the support 3 attached. This detector has the advantage that it is very sensitive at the same time but the disadvantage that even the slightest shift of the contact point between the screw 2 and the crystal piece extensive changes in sensitivity of the Detector can cause. The reasons for this deficiency of the detector are revealed result from the following.

Die vom Erfinder durchgeführte nähere Untersuchung der unipolaren Le^fähigkeit besonders des Molybdänglanzes hat ergeben, daß mit Stellen von positiver Gleichrichtwirkung häufig Stellen von negativer Wirkung in derselben Fläche des Kristalles nahe benachbart sind. (d. h. der gleichgerichtete Strom besitzt im zweiten Fall entgegengesetzte Richtung wie im ersten Fall). Zwischen den kleinen Bereichen, innerhalb deren die Gleichrichtwirkung der einen oder der anderen Art sehr stark ausgebildet ist, liegen andere Bereiche, innerhalb der sie schwach oder gar nicht vorhanden ist (neutrale Bereiche). Wird eine derartige ganze Kristallfläche oder ein großer Teil derselben mit einem metallischen Leiter in Berührung gebracht nnd Wechselstrom durch die Berührungsfläche gesandt, so findet daselbst keine Gleichrichtung des Stromes statt, weil er in der einen Richtung durch die positiven und die neutralen Bereiche geht und in der anderen Richtung auf die negativen und neutralen Bereiche verteilt wird. Deshalb muß man, um eine stark ausgeprägte Gleichrichtung zu erreichen, den Kontakt auf einen Bereich mit gleichsinniger und möglichst hoher Wirkung beschränken. Aus diesem Grunde wird die Kontaktfläche überhaupt klein gemacht, undThe closer investigation of the unipolar capability carried out by the inventor especially the molybdenum luster has shown that with points of positive rectifying effect often places of negative effect in the same face of the crystal are close to each other. (i.e. the rectified current is opposite in the second case Direction as in the first case). Between the small areas within which the rectifying effect of one or the other type is very well developed, there are other areas within which it is located weak or nonexistent (neutral areas). Becomes such a whole crystal face or a large part thereof brought into contact with a metallic conductor and alternating current is sent through the surface of contact, there is no rectification there of the current because it goes through the positive and neutral areas in one direction and in the other Direction is distributed to the negative and neutral areas. Therefore one has to, in order to To achieve a strong rectification, make contact with an area limit the same direction and the highest possible effect. For this reason, the Contact area made small at all, and

Claims

the contact is adjusted so that it only includes the most sensitive area. A contact of this type is called "effective", while the large contact mentioned above is called "neutral". In the detector shown in Fig. Ι the effective contact is brought about that the screw is brought to press with its tip against a sensitive point of the ίο upper surface of the crystal piece ι, while the neutral contact by touching the crystal piece ι with of the metal plate 5 or the solder or the like located between the latter and the crystal piece. Since the sensitive areas of the surface of the crystal piece have an extremely small extent, it is easy to see that even an insignificant change in shape of the support 3 or the screw 2 ', such as such. B. caused by a shock, the sensitivity of the detector can reduce to a considerable extent. The sensitivity also depends on the pressure between the screw tip and the crystal chip, in that the sensitivity is greatest at low pressures and decreases rapidly when the pressure is increased. A change in temperature, which causes the parts of the detector to expand slightly unevenly, is sufficient to cause large changes in sensitivity. All of this contributes to making the detector entirely unsuitable as a means for a more or less reliable, quantitative measurement of the intensity of radiotelegraphic signals or the like. According to the invention, to eliminate the mentioned disadvantage, the pressure contact previously used as an effective contact (a screw, a tensioned metal wire 0 very small ball 0. This arrangement does not reduce the sensitivity of the detector. only unchangeable, but also larger than with previously known detectors, which latter depends on the low pressure to be exerted against the crystal or the unipolar conductor. FIG. 2 of the drawing shows, in partial section, an embodiment of a detector set up according to the invention, and FIG. 3, likewise in partial section, a modified form of the same. According to FIG. 2, two metal plates 12, 13 with pole terminals 14 and 15 for lead wires 16 and 17 are attached to an insulating base 10. A piece of crystal 18 is soldered to the plate 12. On its upper side, a very small metal ball 0. The metal ball is either attached directly to the sensitive area or after that area has been covered with a metal coating by dusting, electrolysis or the like, which then forms the solid contact. In order to protect and secure the contact even better, the whole thing is expediently covered with an insulating material, e.g. B. Varnish, coated. Such fixed contacts can of course be attached to several sensitive points on the crystal surface. This has the advantage that the resistance and the sensitivity of the detector can change within wide limits. Finally, the neutral contact according to FIG. 1 can be replaced by one or more fixed contacts. Such an example is illustrated in FIG. 3. A piece of crystal 21 is inserted here in an insulating holder 22 to which two metal plates 23, 24 are attached, each of which is connected by a thin metal wire 25 or 26 to a very small ball soldered to the piece of crystal 21. P ate ν τ-An Proverbs:

1. Crystal detector with a neutral and an effective contact, thereby characterized in that the effective contact from one to a sensitive area of the There is limited solid contact with the crystal, either by coating the named place with a metal coating (by means of dusting, electrolysis, etc.) and soldering a very small metal contact to the metal coating or by soldering of the latter contact is made directly on the crystal.

2. modification of the detector according to claim i, characterized in that the neutral contact through a firm, effective contact of those specified in claim 1 Kind is replaced.

3. crystal detector according to claim 1 or 2, characterized in that more than two fixed, effective contacts of the type specified in claim ι attached to the crystal are.

1 sheet of drawings.