Abstract: A telecommunication system has a supply circuit to supply power to a telecommunication line. The telecommunication line is connected to a telecommunications subscriber device. The supply circuit has a first electronic impedance that is connected between a first voltage reference terminal and a first wire of the line, and a second electronic impedance that is connected between a second voltage reference terminal and a second wire of the line. The first electronic impedance has a first transistor, and the second electronic impedance has a second transistor. The supply circuit further has a first impedance multiplying circuit with a third transistor, and a second impedance multiplying circuit with a fourth transistor. The first impedance multiplying circuit multiplies the impedance of the first electronic impedance, and the second impedance multiplying circuit multiplies the impedance of the second electronic impedance.

Abstract: A power supply with improved power factor comprises a first rectifier circuit connected to an electric mains and which has first output terminals for supplying a first pulsating direct voltage. A buffer capacitor is connected parallel to the first output terminals and an inverter is connected to the buffer capacitor. A second rectifier circuit is connected to the mains and has second output terminals for supplying a second pulsating direct voltage. A flyback converter is connected to the second output terminals and has output terminals connected parallel to the buffer capacitor. The converter increases the power factor of the power supply and is operative to supply a maximum power which is substantially lower than the maximum power of the first rectifier circuit. The converter comprises a transformer with a primary winding and a secondary winding.

Abstract: A supply circuit for a two-wire telecommunication line includes a voltage adjusting circuit section coupled between one of the wires and a first reference potential point and further includes a current source coupled between the second wire and a second reference potential point. A transistor in the voltage adjusting circuit section has a first main electrode coupled to the first wire, a second main electrode coupled to the first reference potential point, and a control electrode which is coupled to the first wire by way of a capacitor. In order for the supply circuit to meet strict requirements as to symmetry and demodulation, the control electrode is also coupled to the first reference potential point by way of a threshold voltage diode, which may be a zener diode. A voltage control circuit coupled to the threshold voltage diode forms a feedback loop for maintaining the line voltage at a selected value despite the presence of disturbing signals on the line.

Abstract: A supply circuit for supplying a smoothed direct current to a load comprises a series FET element in series with the load resistance. The supply circuit is fed from the AC supply network via a rectifier 54 and a smoothing capacitor 52 causing a ripple voltage to be present on the input terminals 2-1 and 2-2. The direct voltage component of the input voltage is present across load resistance 60 and the alternating voltage component of the input voltage is present across transistor 10. In the case of known supply voltage circuits the voltage drop across the series element is selected to be equal to the maximum peak-to-peak value of the alternating voltage component thereby causing unnecessary power dissipation to be developed at a minor ripple amplitude. This will cause rapid ageing of the series element. The supply circuit in accordance with the invention comprises a comparator 42 comparing the voltage across FET transistor 10 to a threshold voltage.

Abstract: The invention relates to an opto-electrical signal converter for linearly converting a signal consisting of an alternating current superimposed on a direct current into a signal consisting of an alternating voltage superimposed on a direct voltage. Such a converter comprises the combination of a light diode and a photosensitive element optically coupled therewith, which combination is designated as optocoupler.The invention has for its object to provide a converter having a good linear signal transmission, the value of the output signal of the converter being independent of the properties of the optocoupler used.For this purpose, the converter is provided with a transistor, of which a semiconductor junction connected to the base of the transistor is AC-connected parallel to the base-emitter junction of the transistor and is DC-connected in series with a stabilization circuit.

Abstract: An opto-electronic repeater provides by means of a differentiation circuit and a trigger circuit a considerable extension of the life of the radiation-emitting element by reducing the duty cycle of the control signal for the radiation-emitting element.

Abstract: An electronic transmitter for direct current telegraphy systems. In order to limit cross-talk between neighboring telegraph lines it is known to filter telegraph signals prior to transmission to "round-off" their edges. In the present electronic transmitter telegraph signals are given approximately "sinusoidal edges" by the use of a function generator. In FIG. 1 an electronic transmitter comprises an input circuit 1, a switching circuit 2 and an output circuit 3. Binary information signals at an input produce telegraph signals on a telegraph line 6-6'. The output circuit 3 comprises two function generators 15 and 17 and a current source 21. Switches 11 and 14 in the switching circuit 2 control which function generator is operative in response to command signals D.sub.1 and D.sub.2 from the input circuit. The result is that current pulses from the current source 21 have exponentially varying leading and trailing edges which approximate the sinusoidal edges as shown in FIG. 2.

Abstract: An electronic relay arrangement that is suitable for use as a repeater in systems for single-current as well as double-current telegraphy comprising an input circuit, an output circuit and a transmission circuit interposed between the input and output circuits. The input circuit comprises a current switching device which responds when a threshold current value of the telegraph line current is exceeded and causes a current, having a predetermined constant value, to flow through the transmission circuit. The electrical isolation between the input and output circuits can be effected by, for example, a light-emitting diode in the transmission circuit and a photo-transistor.

Abstract: An electronic transmitter for direct current telegraphy by means of polar line currents has a switching circuit that selectively connects one of the two poles of a telegraphy battery through a unipolar constant current source to a telegraph line, and an output filter having a capacitor in parallel with the telegraph line. The higher frequencies in the telegraphy signals are sufficiently suppressed to keep the noise level in adjacent telephone lines below a prescribed value because the output filter also has two complementary branches in parallel with the telegraph line, at least one of the two branches supplying, in response to a polarity transition of the line current supplied by the current source, a correction pulse having a polarity opposite to the line current to the telegraph line. This output filter is assembled from small-sized, low-priced elements so that an efficient miniaturization of the electronic transmitter in its entirety can be realized.