US1823072A - Rectifier relay circuit - Google Patents

Description

Patented Sept. 15, 1931 UNITED STATES PATENT v'o1-FICE HALSKE AKTIENGESELLSCHAFT, F

GERMAN COMPANY SIEMENSSTADT, NEAR BERLIN, GERMANY, A

nnc'rrrrnn RELAY CIRCUIT Application med my a1, 192e, serial No. izaias, and m Germany september 15, 1925.

` and particularly their sensitivity.

Another object of this invention is to control the operating periods of the relays in such circuits.

Relays operated by voice or other signaling currents in the line are employed in echo Suppressors, reaction Suppressors, voice operated repeaters and the like. In such circuits it is the eneral practice to employ vacuum tube amp ifier-rectifiers for operating the relays. Generally these circuits are so arranged that the amplified speech currents act on a rectifier tube operating at the lower bend of the anode current characteristic curve. The direct current component of the anode current produced actuates a relay which controls corresponding contacts. With such a circuit it is necessary to use a grid battery which is considerablylarger than that required'for ordinary repeaters, in order to bias the grid of the rectifier sufficient-ly negative. It is also necessary to use relatively sensitive relays since the rectified anode current attainable is small because it only consists of the positive half waves of the sinusoidal currents impressed on the grid circuit.

In accordance with a feature of this invention, proper operation of the rectifierrelay circuit -1s attained using a grid battery of ordinary size and a relay of comparatively low sensitivity, by positively biasing the grid of the rectifier tube and using a condenser and resistance in parallel in the grid circuit and a coil of large inductance in the anode circuit of thevrectitier tube. This arrangement has the additional advantage that the actuating and releasing periods of the associated relay can be controlled by means of the condenser and resistance as explained hereinafter.

Instead of working on the lower bend of the characteristic curve, a tube connected in the manner of this invention works on the upper portion of the curve. In the normal condition, i. e. in the absence of an alternating current wave impressed upon the grid, the full emission current flows in the relay connected in the anode circuit due to the fact that the grid is positively biased. When an alternating current wave is impressed upon the grid circuit the effect is to reduce the current in the anode circuit causing the relay to release. This reduction in anode current is caused by the reduction in the grid potential produced by the speech currents which, due to the bend in the grid current characteristic of the tube, cause an increase in the grid current which charges the condenser and increases the drop across the resistance in shunt thereto thus decreasing the potential of the grid. After the cessation of the alternating current the anode current can only rise again to the normal value required to actuatethe relay after the discharge of the condenser. The charging and discharging periods of the condenser may, however, be readily controlled by proportioning the values of the condenser and resistance in shunt thereto to consequently control the actuating and releasing periods of the relay.

This invention can be more readily understood by reference to the following detailed description in connection with the drawing which shows one embodiment thereof.

The drawing shows an amplifying tube 3 and a rectifying tube 4 connected in tandem through an interstage transformer 5. The controlling speech currents are supplied through the resistance network 6 to the input transformer 7 The cathodes 8 and 9 of the tubes 3 and 4 respectively are connected in series to the battery 10 for receiving heating current therefrom. A ballast lamp 19 is included in the cathode heating circuit. The grid 11 of the tube 3 is connected through the secondary of the transformer 7 to the negative terminal of battery 10 to give it a negative bias with respect to the cathode 8. The grid 12 of the tube 9 is connected to the positive side of the battery 10 to .positively bias it with respect to the cathode 9. The condenser 13 and resistance 14 are connected in parallel with one another -in the grid circuit of tube 4. Battery 15 serves to supply space current to both tubes. The rela 16 is connected in series with the high in uctance choke coil 17 in the anode circuit of the tube 4. The circuit operates as explained above, the armature 18 of the relay 16 being held out of contact in the normal condition. When voice currents are impressd upon the circuit the current in the relay lWinding is reduced, releasing the armature 18.

Since the impedance of the coil 17 is high com ared` to the impedance of the .relay win 'ng the latter may be shunted by a condenser if desired.

What is claimed is:

1. A rectifier-rela circuit comprising an electron discharge evice having an anode, a cathode, a control electrode, and circuits therefor, a circuit-closing electro-ma etic relay connected in the anode circuit o said device, means for ositively biasing said control electrode su ciently to cause substantially saturation current to flow in said anode circuit to energize said relay, a resistance and a condenser in parallel in the control electrode circuit of said device for developing a negative biasing potential on said control electrode when control Waves are impressed on the control electrode circuit, and hi h impedance means included in said anode c1rcult in series with said relay, said parallel resistance and condenser being proportioned with respect to the other elements of the circuit to control the actuating and releasing periods of said relay.

2. A voice operated rectifier-relay circuit comprising a space discharge device having a cathode, an anode, a control electrode, and circuits therefor, a circuit-closing electromagnetic relay connected in the anode circuit of said device, means for applying a 'positive biasing potential tosaid control electrode of suicient value to cause normally substantially saturation current to lovv in said anode circuit to energize said relay, means for impressing voice current Waves on the control electrode circuit, a condenser and a resistance connected in parallel in said control Aelectrode circuit for developing a negative biasing potential on said control electrode when voice current waves are impressed on said control electrode circuit and a choke coil of high inductance included in series with said relay in said anode circuit, said parallel resistance and condenser and the inductance of said choke coil being relatively proportioned so as to regulate the actuating and releasing periods of said relay.

3. A voice operated relay circuit comprising an electric discharge device having cathode, anode and grid elements, a cathodeanode or output circuit containing a relay,l a grid circuit containing a source of voltage biasing the grid positive such that in the absence of voice currents in thegrid circuit

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