Abstract: High-pressure discharge lamps may explode at the end of their life. In order to be able to predict an explosion, the gradient of the operating voltage is evaluated. If a risk of explosion is detected, the lamp operation is interrupted.

Abstract: High-pressure discharge lamps may explode at the end of their life. In order to be able to predict an explosion, the gradient of the operating voltage is evaluated. If a risk of explosion is detected, the lamp operation is interrupted.

Abstract: To provide for effective control of a discharge lamp, typically, a sodium gh pressure discharge lamp, which operates in two phases, namely, a power pulse phase, followed by a holding phase, without extensive and complex electronic circuitry, two individual oscillator systems are provided, one for each phase; the oscillator systems include a first power burst oscillator formed as a first half bridge by two transistors (T1, T2), and an individual connecting current limiting inductance (L1) to the lamp (E), and a second oscillator including a two-transistor second half bridge (T3, T4) and an individual current limiting inductance (L2) coupled to the lamp. The respective oscillators are controlled, in a closed control loop, by a burst generator (BG) and a holding pulse generator (SG), each of which provide their signals to a logic circuit (LK) which provides for exclusive control of the respective first or second half bridge.

Abstract: To operate a discharge lamp, and more particularly a low-power high-pressure discharge lamp, only in quiet or stable lamp operation, a microprocessor (MC) is provided which establishes a test phase of limited time duration during which the frequency of operation of the lamp is varied by frequency modulation within a predetermined range. Lamp operation is monitored, for example by deriving a test voltage across a coupling capacitor (C6) receiving lamp current. If the monitored voltage, which is representative of lamp operation, shows that the lamp operates quietly and stably, the then pertaining frequency is stored by the microprocessor and, after the test phase is finished, the lamp is operated within a frequency window formed by the largest number of contiguous modulation frequencies which are suitable for, or result in, stable lamp operation. The test phase is carried out repetitively, at least upon each energization of the lamp, so that different operating characteristics of the lamp (e.g.

Abstract: To permit, selectively and in accordance with safety or standardization rirements, connection of different electrical supply devices, such as extending cables or terminal posts, pins or clamps, to a single, standardized operating or accessory circuit retained on a circuit board (2) within a housing (1), the housing is formed with a connection receiving portion (5a) selectively differently constructed connection parts (3, 3') forming insert elements are provided, dimensioned and shaped to fit into the receiving portion of the housing. The connection parts, forming the insert element, thus can be constructed according to the respective safety or standardization requirements without otherwise affecting the structure of the substantially more expensive operating or accessory circuit in the housing.

Abstract: To prevent bowing of the arc of a high-pressure discharge lamp operated horizontally, the lamp is supplied with alternating current of between 10 kHz and 100 kHz, in which the frequency and wave shape of the alternating current portions of the supply are so selected that standing radial acoustic resonances will be formed within the discharge medium or fill in the discharge vessel, which standing radially directed acoustic resonances suppress or counteract bending of the discharge arc due to convection phenomena.

Abstract: To ensure ignition of a high-pressure discharge lamp, for example a metal vapor halogen high-pressure dicharge lamp which has an ignition circuit, and is operated by direct current from an inverter circuit controlled for pulse width modulation, current flow to the lamp is extended in time upon initial energization thereof so that an initial hot spot which forms on an electrode can remain hot to establish a stabilized arc. This extension of current flow can be obtained by an R/C circuit in parallel to the output or storage capacitor (C.sub.A) of the inverter circuit (FIG. 1) or by an NTC resistor (H) in series with the lamp, or by a resistor which is short-circuited by a relay contact as the lamp operates, or the like.

Abstract: A switched mode power supply (SNT) is coupled to a source of d-c energy (U.sub.Batt) and provides electrical energy to a lamp within widely varying limits. The switching conditions of the switched mode power supply are controlled by an operation control circuit (ADD) which has a current sensing resistor, serially connected to the lamp, to provide a lamp current signal, and a voltage divider (R2, R3) connected across the lamp to sense lamp voltage and provide a lamp voltage signal. The lamp current signal and the lamp voltage signal are added, compared in a comparator formed by an operational amplifier (IC2-A), with respect to a reference setting power level, and the output signal from the comparator is coupled back to the switched mode power supply to control the switching rate thereof, based on the instantaneous lamp current and lamp voltage. Excess voltage can be compensated by providing either an active semiconductor switching network (T1, T2, FIG.

Abstract: A control circuit for controlling a known active harmonic filter operating as a step-up converter in a power supply with sinusoidal network current input and a power factor of almost unity. The step-up converter comprises: a main rectifier, a storage inductance (L.sub.S), a cross-connected high-speed transistor (T.sub.Q), a diode (D1) and a power storage capacitor (C.sub.L). The high-speed transistor (T.sub.Q) is controlled by a first threshold switch (STc) whose input is controlled by a control capacitor (C12) coupled to receive a signal representative of instantaneous rectified d.c. output voltage (U.sub.E), instantaneous power output voltage (U.sub.o) and a signal representative of the charge state of the inductance.

Abstract: The oscillation generator includes an oscillator circuit, a push-pull amplifier with inductive positive feedback connected in the circuit, a piezoceramic atomizer vibrator element, and a load-dependent regenerative feedback coupling connected to the circuit. The coupling is in the form of a tunable frequency-selective sensor having outputs connected to the inputs of the amplifier.