Abstract:
Transformer comprises a core (K1, K2), a primary winding (W1) and at least one secondary winding (W2), which are arranged as conductors on one or more layers of a flat carrier, and a coil former with a chamber system having chambers (C1, C2), which accommodate the layers with the windings (W1, W2). At least one of the chambers (C1, C2) is closed at least in regions, with the result that long distances for creepage paths are obtained. As a result of this, it is possible to adhere to existing safety regulations for the mains power supply isolation even with very compact dimensions and/or with full utilization of the width available for the conductor tracks. The chamber system can be formed from two or three plastic parts (P1, P2, P3) by mating. The layers with the conductor tracks are routed laterally out of the chamber system in order to make contact with terminals. In an advantageous refinement, webs with metallized slots are arranged on walls of the chamber system, in order to make contact with the conductor tracks (L). The slots are, for example, notched or trough-shaped depressions in which the carrier layers latch into place and are held thereby. The electrical contact afforded by the slots can be additionally supported by a solder-paste application with subsequent soldering. The lateral contacts mean that plated-through holes are avoided in the case of the carrier layers, with the result that the latter can be produced significantly more inexpensively. By virtue of the chamber system, it is possible for the openings in a core, for example an E/E or E/I core, to be utilized significantly better if the transformer has to comply with a sufficient insulation strength, such as in the case of mains power supply isolation, for example.
Abstract:
A current supply circuit for an electronic apparatus having standby, normal and economy modes of operation includes a remote control receiver which responds to a remote control signal from a remote control unit to select either mode of operation. A voltage source provides a main voltage which is detected to produce a switching voltage when the main voltage is present. The switching element of a voltage responsive switch is connected to a first input contact in the presence of the switching voltage and to a second input contact in the absence of the switching voltage. The output contact of the voltage responsive switch is connected to an input terminal of the remote control receiver and to a first input terminal of the filter. The output contact is selectively connected to the first and second input contacts in response to the respective presence and absence of the switching voltage to apply a first operating voltage to the first input contact in the presence of the switching voltage and a second operating voltage to the second input contact to place the current supply circuit into the economy mode of operation in the absence of the switching voltage.
Abstract:
DC-converter with a switch-mode power supply, in particular for continuously operating magnetrons of the type generally used in microwave ovens. By a special tuning of an oscillating circuit (16,18) forming the control voltage for the switching transistor (9) it is achieved that the switching transistor off-time as well as its duty cycle can be varied within large ranges.
Abstract:
The switched-mode power supply comprises a secondary winding and four diodes for producing two rectified voltages of the same polarity, one of which can be regulated. A connection of the unregulated voltage has connected to it a variable Zener diode as an error amplifier for transmitting a regulating signal to the primary side. The driver stage provides a pulse-width-modulated square-wave signal for driving the switching transistor which is arranged at a high potential between the operating voltage on the input side and a first connection of the primary winding. The second connection of the primary winding is connected with a Zener diode and provides a stabilized voltage for the driver stage. Arranged between the driver stage and the control electrode of the switching transistor there is a differentiating element which produces positive and negative switching voltages for controlling the switching transistor.
Abstract:
A line deflection circuit for a television receiver or a switched-mode power supply operate with a switching transistor that is connected in series with the primary winding of a transformer and is periodically switched on and off by a switching voltage. In such a circuit, appreciable turn-on and turn-off losses, which reduce the overall efficiency of the circuit, are produced at the switching transistor, particularly at higher operating frequencies. Within a control circuit a DC voltage source is connected to the base of the switching transistor via a periodically actuated switch element and a coil having a core and a tap. The two parts of the coil are wound in opposite senses, and the tap is connected via a diode to ground or to the emitter of the switching transistor. The control circuit further includes a charge-reversal path via which, during a demagnetization phase of the coil, the energy stored in the coil in the form of a current is transferred in the form of a negative voltage to a capacitor that is coupled via a second diode to a first part of the coil. The negative voltage is applied during a residual time subsequent to the demagnetization phase as a reverse voltage to the base of the switching transistor.
Abstract:
It is known to provide a large screen area using a picture tube having a plurality of guns. The object is to provide a transition of continuous brightness, so that the partial picture transitions are no longer perceptible.This is achieved in that a picture tube without a shadow mask, but with optical sensors, index regions and optical walls is employed, so that a precise detection of the beam is possible and the partial picture transitions are no longer perceptible.Especially for television receivers and monitors.
Abstract:
A line-powered phase-control circuit includes a source of rectified voltage. An inductance is responsive to the rectified voltage. A switching transistor has a conduction path connected in series with the inductance at a junction. One plate of a charging capacitor is connected to the inductance and the rectified voltage charges the charging capacitor through a first diode. A switch mode power supply includes a transformer having a primary winding connected between the junction and the plate of the charging capacitor. A second diode is connected between the inductance and the junction.
Abstract:
An inverter circuit for driving a load including an inductive component such as an inductive cooking appliance, and being powered by a pulsating DC source obtained by rectifying a single phase AC power input. The inverter includes a pair of power transistors operating in a push pull mode with a multiple winding transformer, and operating at a frequency in excess of the AC power line frequency. Alternate switching of the power transistors is fed back through the transformer to control the switching of the transistors. The improved circuit provides positive switching of the power transistors at the higher frequencies regardless of the fluctuations in amplitude of pulsating DC power input, by triggering the generation of constant firing pulses from a fixed voltage source to the transformer windings in a feedback arrangement. A starting oscillator is also provided to initially start, or restart, the inverter; and the starting oscillator is automatically decoupled from the inverter when the inverter is operating. In an alternative embodiment, the starting oscillator also provides the function of positively switching the power transistors after the inverter is functioning by changing its mode of operation from an oscillating circuit to a pulsing circuit.
Abstract:
The current which passes through the vertical deflector of a transistorized color television receiver is produced by a circuit comprising an active switch controlled and modulated at the line frequency and supplied by line retrace pulses delivered by the secondary winding of a line transformer. The voltage at the terminals of an assembly compring a capacitor in series with the vertical deflector has a constant sign which is independent of the current passing through the deflector. The same secondary winding of the line transformer supplies both the vertical scanning circuit and a rectifier circuit for producing a d.c. voltage, in particular for the supply of video amplifiers.
Abstract:
Step-up switching regulator power supply device comprising, connected between the poles of a rectifier circuit supplied by an isolating voltage step-down transformer and loaded by a first filter capacitor, and inductance and the collector-emitter path of a first switching transistor of NPN type, a first diode whose anode is connected to the junction of the inductance and to the collector of said transistor and whose cathode is connected to a second filter and storage capacitor supplying a voltage at its output which supplies a horizontal deflection circuit of a television receiver.This horizontal deflection circuit which comprises in cascade a horizontal oscillator, a driver stage and an output stage, forms an integral part of the circuit controlling said first transistor and determines the repetition period of the switching, because it is started under an initial voltage slightly less than the unregulated input voltage of the device.The switching transistor is being turned off in synchronism with the turning off of the trace switch transistor by using flyback pulses of negative polarity to bias the base thereof.