Read the latest magazines about Astable and discover magazines on Share. Astable Timer – Electron Electronics LES MULTIVIBRATEURS ASTABLES. Read the latest magazines about Multivibrateurs and discover magazines on The HEFB is a retriggerable astable multivibrator that can be configured as Monostable (one-shot) or astable (free-running) operation.

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Supply device according to any of the preceding claiums, characterized in that the control circuit SC, SCAwith the exception mmultivibrateur the regulator stage 30 which is fed by the output voltage VSis supplied by the input voltage VE.

Stabilized-power supply device for a line deflection circuit in a television receiver.

Is then obtained at the start of the peak voltages V 19 higher overvoltage on the collector of transistor 11 1 during its locking, the fact that, in the formula V19 max. This circuit 44 comprises a resistor and a Zener diode connected in series between the input and the primary mass 8 and provides, by means of a resistive divider circuitoptionally adjustable, connected in parallel with the Zener diodethe reference voltage at the input of the comparator Figure 11 shows the complete block diagram of a BS feeder of Figure 1 including the SC control circuit is respectively formed by the driving circuit 20A of Figure 4, by the modulator 10B of the Figure 8 and the regulator stage 30 of Figure 10, with some variations.

P BAC Séries

The energy transferred during each line period T H by the adtable circuit 10 to the output stage 30 via the transformer 20 can therefore cry: Lapsed in a contracting state announced via postgrant multivibrateu. The second transistor form with the resistorsand Zener diode, an analog stage voltage comparator is blocked until the voltage applied to its base exceeds a threshold voltage resulting from the addition of the Zener voltage Vz of the diode to the voltage V BES about 0.

This winding 21 of line transformer 20 whose primary winding is usually connected in parallel with the coils of the line deflection in the circuit of the output stage 30 of the scan line to provide via secondary windings of the voltage supply, in particular cathode ray tube will be called in the following power winding, because the transfer of energy between the chopper circuit 10 and the output stage 30 will be conducted through it.

Circuit provided in an image display device and for generating a line deflection current of sawtooth. The second capacitor then turns to a negative voltage that will extend the duration of the blocking of the transistor beyond the disappearance of the pulse back-line, a portion of the trace period of scanning, in order to have an adequate control range.

Multivibrzteur collector current of the transistor is a current that discharges the capacitor over the transistor of the locking slots so as to reduce the slope of the clurs voltage across the capacitor Supply device according to claim 1, characterized in that the transistor 11 of the second switch 15 is controlled by means of a regulating circuit 40 powered by an auxiliary winding 25 of the transformer 20 which provides a signal having one peak amplitudes is proportional to the voltage at the terminals of the supply capacitor 33 of the output stage 30charged with the chopper circuit 10 and the peak-to-peak is proportional to a very high voltage supplied by another winding 23 of the transformer 20the regulating circuit 40 by varying the delay of courrs moment transistor blocking 11 with respect to flyback pulse rising edge generated by the opening of the first switch 36, The inductance reduced by the line transformer in xstable switching circuit is substantially equal to the inductance of the line-deflection coil multiplied by the square of the transformation ratio between the first and second windings of the transformer.


It is essentially constituted by an assembly called well known differential amplifier having two inputs the first of which receives an adjustable fraction of the voltage at stabilize, constituted, in this case, the output voltage VS of the supply device BS, Mutlivibrateur 1 and whose second input receives a stable reference voltage which is usually developed within this stage as in most switching voltage regulators or known ballast.

The multivibratuer amplitudes of peak-to-peak current i 31 t hence the width of the excursion of the beam scanning the screen and the voltage V t hence the THT depend on the value of the V direct voltage which feeds the output stage of the horizontal scanner 30 and which in most switching power supplies of the prior art, is regulated and stabilized by modulating the duration asttable the saturated state the duty ratio of the transistor of cutting 11 as a function of the amplitude of the flyback pulse taken from an auxiliary multiivibrateur of the line transformer 20 and therefore the voltage across the capacitor 33 and optionally the voltage rectified and filtered courw.

The diagram C of Figure myltivibrateur shows the corresponding waveform of the current IL running through the inductor L. The rising edges of the pulses supplied by the output of the rocker 41 substantially coincident with those pulses flyback, their descent or falling edges that occur with variable delays with respect to the first are used to trigger, courx through an inverter stage, a second flip-flop 45 whose output feeds the base of chopper transistor 11 to block it.

In other words, in the feed device by cutting object of the invention, the scanning-line circuit forms part of the control circuit of the switching transistor, since it is this circuit that determines, upon its startup by setting turn on the device, the recurrence period of the rectangular signal with variable duty cycle, provided by the modulator pulse width. The average value of the voltage waveform of v t to terminal is equal to qstable DC supply voltage V across the power supply capacitors 33 and move or effect S Such a variable phase delay is obtained from flyback pulses taken from one of the windings of the transformer 20 such that the winding 21 itself or, as illustrated in Figure 1, the auxiliary winding Regulating the level of the output voltage VS is performed here in a conventional manner, by varying the duty cycle, that is to say the ratio quotient of the length of the conduction interval of transistor T1 and the sum of the respective lengths of multivibrateuur of its conduction intervals and successive locking, depending on the desired output voltage VS determined by comparison with a stable reference voltage.

The auxiliary winding 25 supplies to the multivibraheur of the voltage waveform control circuit comprising the flyback pulses on line with a negative polarity, for example, similar to that shown in the diagrams C of Figures 2 and 3.

These pulses can trigger a flip-flop of variable duration depending on the error voltage astavle by a comparator in the form of differential amplifier, whose one input receives a voltage corresponding to either the positive amplitude of 21 V t proportional to the voltage V 33 V at the terminals of the supply capacitor 33 of the output stage 30 or to the peak-to-peak pulse of flyback, that is proportional to THT, or a combination of mjltivibrateur two criteria.


When the coupling between the first and second windings is loose, the resonant frequencies of resonant circuits each formed by the cutting inductance and the tuning capacitor, and by the inductances of the deflection coils and the first winding of the transformer in parallel with the return capacitor, can be very different and the times of recurring blockage of scanning switches and cutting multivihrateur followed by half an oscillation period of the oscillating circuits can be out of phase with respect to each other.

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Supply device according to claim 6, characterized in that the comparator transistor T3 is further polarized on its base through a resistor R8 connecting it to the positive pole P of the input voltage VE source, in such a manner that it remains saturated in the absence of line flyback pulses from the line deflection circuit, thus maintaining the chopper transistor T1 in its blocked state.

Il sagit dun vecteur representant une grandeur sinusoidale. The output of the control stage 50 called a “driver” in the Anglo-American literatureconnected to the output of the control circuit 40, feeds the base of the switching transistor 11 of the chopper circuit It should be noted that the use of a bidirectional switch with unidirectional control comprising a switching transistor and a diode, mounted to drive in opposite directions and connected in series with an inductor constituted by the winding of a transformer and parallel with a capacitor ensuring the agreement of the inductance at the opening of the cut-off switch is known from dE-B In Figure 1, the line transformer 20 comprises, moreover, a very high voltage winding 23, one terminal can be connected astahle earth 39 or terminal of the coil 22 and the other terminal is joined to the entrance of the very high-voltage rectifying circuit or the multivibratuer multiplier multivibrateug shown in a conventional manner, and an auxiliary winding 24 which can be used to feed multiibrateur a low voltage rectifier assembly, a mounting charge controller or the filament of the cathode ray tube not shown.

This high stall persists until time t4 after time t2 of the beginning of the next pulse of Return- licne whose control before the front bbcage the first transistor T1, when the waveform VI becomes multivihrateur than the voltage VR control. Diode D1 then being polarized upside down, it ceases to conduct, and the inductor L together by the first transistor T1 between the positive and negative poles P N of the source providing the DC input voltage VE non- regulated, then conducts a current IL increasing linearly so as to store energy which increases with the square of the duration of conduction of the first transistor T1, until the locking thereof.

The second e of these diodes D3 has its cathode connected to the base of a third transistor T2 of the NPN type and the one terminal of a second resistor R2 ohms. The circuit is basically the same as in Figure 11 and will be described below as differences. The control stage 47 comprises a diode whose cathode is connected to the input of the circuit 40 receiving the flyback pulses of negative polarity and having its anode connected to the negative plate of a smoothing capacitorto one terminal of a resistive voltage divider circuit comprising a potentiometer between the two resistorsin series and the anode of a Zener diode