DE209582C - - Google Patents

Description

έϊ / ΐ ^ -ίηϊ / α νι Λολ

IMPERIAL

PATENT OFFICE.

PATENT LETTERING

- JV * 209582 - CLASS 21 α. GROUP

AKTIEN-GESELLSCHAFT MIX & GENEST

TELEPHONE AND TELEGRAPH WORKS

in SCHÖNEBERG-BERLIN.

In some line dialing systems with central battery operation and direct current calls, the two connected speech sets are simply connected in series, while in others Systems the parallel connection of the apparatuses has been selected using the Stoneian circuit principle. Both Types of circuit have the disadvantage that the called station's alarm clock lasts so long

ίο continues pawing until the remote receiver has picked up will. This phenomenon is due to the fact that after calling a stream of the calling station flows over the alarm clock of the called party. When one behind the other

15 'circuit, it is the current going through the microphone of the first digit, while in the Parallel connection of the alarm clock is energized because it is parallel to the speaking device or to the inductor of the calling station

■ 20 lies.

According to the invention, this drawback is eliminated by the fact that the microphone current is only closed for both stations when the called subscriber reports.

The drawing shows a line dialer system with three call stations 1, 2, 3, which can be connected to one another by individual lines. The common battery B is used to power both the microphones a and the alarm clock or buzzers. c. One battery line serves as a common return line for the speech currents. In the stations 1 and 2, the line selector d consist of the known automatically triggered pushbuttons, while a crank line selector / is shown for the station 3. It is assumed that point 3 has called point ι. This connection is established by placing the crank on the contact marked no. 1 and pressing the g key to call. As long as no. 1 has not responded, the alarm clock c and the speaking device a, b are connected to the same pole (the + pole) of the battery B at this point. The speech set a, b of call station 3 is also connected to the -f- pole, and so no current can flow through the alarm clock at station 1. When a call is made, on the other hand, the g button places the - pole of the battery on the line for station 1, the alarm clock of which sounds. When the handset or handset of the call point ι is taken off the hook, the - pole of the battery comes through the upper contact of the hook switch and the alarm coils in connection with the line, and a current flows on the one hand from + B through the intercom a, b position 1 and its alarm winding back to - B, on the other hand from -f- B via the speech set a, b to position 3, contact g, switch contact 1, the line to position 1 and via its alarm winding to - B. The alarm clock electromagnet position 1 serves as a throttle

coil and prevents short-circuiting of the speech currents through the battery.

The line selectors d of the call points ι and 2 differ structurally from the facility of point 3.

If small alarm clocks or buzzers with low self-induction ~ are used, a choke coil h can be connected upstream as in point 2. In this case, the alarm clock can also be located between the break contact of the hook switch and the ■ -) pole of the battery for the purpose of complete disconnection during the call.

The circuit can of course also be implemented as a double-line system.

Claims (1)

Patent claim:
Circuit for telephone line dialer systems with central battery and direct current call, in which the speech sets are connected in parallel after the connection has been established and the microphone stream of the calling station runs over the called one, characterized in that the microphone stream of both call stations is only closed when the telephone or handset of the called subscriber is lifted is, for the purpose of avoiding the rattling of the alarm clock before the called subscriber reports. , 1 sheet of drawings.