DE469507C - Circuit arrangement for surge receivers, especially in self-connecting telephone systems - Google Patents

Description

Circuit arrangement for surge receivers, - especially in self-connecting telephone systems In low-voltage technology, for example in S: self-connecting telephones, Relays are often used that respond precisely and safely to short power surges should. When using direct current, there is usually such a current impulse no difficulty because the DC relay mix built with very low inertia and as a result are able to withstand shorter, rapid electrical surges to follow. It is different if you use alternating current for the signals instead of direct current gives. This is very often necessary, for example when the power surges over a pupinized line should be given; as has recently been the case in amplifier technology - is necessary because the Pupin coils are voimagnetized by direct current and thereby become ineffective.

A major difficulty in using alternating current is as follows: A sensitive relay must be as inert as possible in order to be short To be able to follow current changes. When operating with alternating current, however, a -such Relay every single change. follow and as a result several contact shocks during give a power surge. If you want to avoid this, you have to pay the anchor give such indolence to the sensitivity that during the short times in. which the relay when the alternating current passes through zero, completely or nearly is de-energized, due to its inertia, remains in the working position.

It is easy to see that it is very difficult to find the mechanical To adjust the inertia so finely that with approximately zoperiodic alternating current, the armature, - remains in the working position without commuting, on the other hand with the usual current impulses, When the iö current surges are given in about 11/2 seconds, it works safely.

It is already known to use `` Flows of capacitive charge in accordance with the current impulse given in them to be converted into direct current surges. The invention is also used for rush current delivery the charging or discharging currents of a capacitor; but this is the switching arrangement so made that a sensitive AC relay resistance, capacitance _ and a transfer relay is assigned and, according to the invention, the resistance and the capacitance can be set so that the second relay at the beginning of each Current surge responds once and then independently of current fluctuations. O. Like. Until the beginning of the next current surge remains ineffective. This electric Arrangement has the advantage over the one working with mechanical inertia that it can be set very easily with a few attempts.

An example circuit on which the basic idea of the invention should be explained, Fig. i shows. W is the AC power source, for example a current changer, a: call machine> o. Like., T the pulse generator; for example a dial. F is the line to the electoral office, for example. WR is the AC relay. A is the armature of this relay, which is open in the rest position. B and C are electrical branch points. R is an ohnxian resistor, a direct current source, K is a capacitor, L is a direct current relay, for example the actuating relay des- selector, 0r the armature belonging to this relay or the like.

The AC relay WR is set mechanically so sensitively that it is able to follow every change in current and closes the contact once for every period. The direct current source E charges the capacitor K via R and L in the rest position of A. However, since no permanent current can flow through L because of the capacitor K, L is de-energized. If WR is now excited by a current surge, A oscillates back and forth in the rhythm of the change. If A is closed for the first time, the resistor R and the current source E are bridged, so that the capacitor i (can discharge via 'CABL. which in turn drives selector arms forward. When changing over to the next change, A is opened for a moment and K begins to charge. R is now set in such a way that the short opening time of A is not sufficient to fully charge K. The discharge current surge at next conclusion of; A is so small that now L is not actuated. This game repeats itself during the duration of a current impulse with every change of current Charge K so far that at the beginning of the next current surge L is excited again and the contact is actuated once by L. The size of the discharge can be determined by a suitable choice of K and R ngsstromes and the charging time very accurately. and very sensitive by very few; Stop attempts.

Without changing anything in the principle of the invention, the charging current can also be used instead of the discharge current. An example is shown in Fig. 2. The designations are the same as in Fig.-i. W, Cr and F are omitted for the sake of simplicity. If A is closed, K is charged via A E L , the charging current surge causes L to respond. If A drops, 1K begins to discharge through R. By a suitable choice of K and R, the discharge time of the capacitor can be adjusted so that the short opening time of the relay A is not sufficient to discharge K completely. The charging current surge now required to fully charge K at the next end of A is no longer sufficient to make L respond.

Another embodiment is shown in Fig. 3. According to this, the capacitor K in the position of the contacts i, i ', which are actuated from WR by the Battery B charged via resistor R and in the operating position of the contacts 3, 3 'via the relay Leinmalig .discharged. _-

Claims (1)

PATENT CLAIM: Circuit arrangement for surge receivers, in particular in-line telephones, with facilities for securing the recording. of alternating current surges, in which currents capacitive2 charge to transfer the incoming alternating current surges use, characterized in that: a sensitive alternating current relay resistance, capacitance and a transformer relay: s are assigned in such a way that the transfer relay at the beginning of each, contiguous AC sequence responds once and then independently of your AC relay and the current fluctuations caused by this until the beginning of the next. Current impulse sequence remains ineffective.