US2290909A - Arrangement for transmitting current impulses - Google Patents

Description

July 28, 1942. HETTENHAUSEN 2,290,909

ARRANGEMENT FOR TRANSMITTING CURRENT IMPULSES Filed April 21, 1939 lnventor:

Ddecf Cal /emf Source Patented July 28, 1942 ARRANGEMENT FOR TRANSMITTING CURRENT MPULSES Georg Hettenhausen, Kiel, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company Application April 21, 1939, Serial No. 269,101 i In Germany February 12, 1938 Claims.

In arrangements in which communications are transmitted by means of alternating carrier currents it is in some cases necessary also to transmit ringing signals which, for instance, are formed of an alternating current of low frequency and produced with the aid of a magneto. 0n the transmitting side a relay is arranged to affect the carrier frequency in accordance with the ringing frequency. To employ a relay of normal or standard type is not possible, because such a relay would respond to each half-Wave of the low frequency ringing current, whereby the impulse succession on the carrier frequency side would be double that of the low frequency side.

Instead of a non-polarized relay a polarized relay might be employed, because it would then be possible to fulfil the said requirement, if only one contact of this relay were used for affecting the carrier frequency. In this case, however, the disadvantage arises that it will be unknown on which of the contacts the polarized relay would remain resting, that is, the relay might happen to remain in its ringing state. If, in order to avoid this drawback, an electric or mechanical unilateral bias voltage were provided, the sensitivity of the arrangement would be impaired thereby.

Therefore, a non-polarized relay and a rectifier connected in advance thereof have been used. The relay in this case only responds to each second half-wave. In the event of a quick impulse succession, however, or with a high sensitivity, the relay in consequence of a great time constant determining the release thereof, may happen not to drop its armature during the period of no-current. As a result, the ringing frequency will not be properly transmitted to the receiving side.

In order to overcome this disadvantage, the invention proposes to provide a resistance connected in parallel with the rectifier which in its turn is arranged in series connection with the said relay. This resistance is connected in shunt with the rectifier and is calculated to allow a comparatively small current amplitude to flow through the relay. This current amplitude acts to reverse the polarity of the field in the core of the relay, that is to say, the core is demagnetized without the relay responding.

Instead of such ohmic resistance a condenser or a resistance-condenser combination may be connected in shunt with the rectifier.

In the accompanying drawing Fig. 1 shows the circuit arrangement of one embodiment of the invention, while Figs. 2 and 3 represent current curves which serve to explain the operation of arrangements as provided by the invention and Fig. 4 shows a modified circuit similar to that of Fig. 1.

The ringing current produced in a subscribers station T by means of a magneto, for instance, and whose current curve I is represented in Fig. 2, is transmitted to a carirer frequency apparatus and is employed here for keying in impulse-fashion the carrier frequency produced by generator F. The keying frequency is conveyed to a relay E having a contact e. Connected in advance of relay E is a rectifier G which, in accordance with the invention, is bridged over by a resistance A, such as a high ohmic resistance, for instance. In this way the current curve 2, Fig. 3, is obtained which enables a proper modulation of the carrier frequency to be effected by contact e.

As shown in Fig. 4 the element A of Fig. 1 is replaced by a resistance I and condenser 2 in parallel and source F is shown as a direct current source instead of an alternating current source. This modified circuit can be used in place of that shown in Fig. 1 and will produce substantially similar results.

The arrangement may be employed also in the case of ringing over low frequency talking lines, and it may be employed whenever in the case of an impulse transmission a contact is desired to be continuously held in its open or closed position.

What is claimed is:

1. An arrangement for converting alternating ringing current into current impulses of equal frequency, comprising a rectifier and resistance in shunt combination, a non-polarized relay connected in series with said combination to form a series circuit, means for supplying said alternating ringing current across said series circuit and an impulse producing circuit controlled by said relay.

2. An arrangement according to claim 1, wherein said resistance is an ohmic resistance.

3. An arrangement according to claim 1, wherein said resistance comprises an ohmic resistance and condenser in series.

4. An arrangement according to claim 1, wherein said impulse producing circuit comprises a course of direct current and means controlled by said relay for impressing direct current impulses from said source on a signal line.

5. An arrangement according to claim 1, wherein said impulse producing circuit comprises a source of carrier frequency and means controlled by said relay for impressing carrier frequency impulses from said source on said signal line.

, GEORG HE'ITENHAUSEN.

Images