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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To simplify the driver stage was used in place of the switching transistor T1 an integrated Darlington circuit T10 of type BUfor example.
Otherwise, the multivibrator 48 is conventionally synchronized by the trigger pulse applied to its input They have often been combined in particular to the output stage of the horizontal scanning circuit which provides a pulse signal at line frequency, operable to control the cutting. 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, possibly through an inverter stage, a second flip-flop 45 whose output feeds the base of chopper transistor 11 to block it.
Ab initio quartic force fields for anions: As the voltage supplied by the diode D8 is itself regulated, it can be used to power all of the TV with the exception of the scanning-line circuit powered by the voltage VS and the remote control receiver to be able run continuously also in the standby state to detect the power-on signal. Switched supply voltage device with controlled gating, combined with the line deflection of a fernsehempfaengers, which it feeds.
It will therefore operate independently from the power sector supply terminals 1, 2 that feed on the one hand, the rectifier circuit 5 and, secondly, the autonomous power source The second transistor form with the resistorsand the zener diodea stage analog voltage comparator is blocked until the voltage applied to its base exceeds a threshold voltage resulting from the addition of the voltage V Zener diode Z to the voltage V BEM about 0.
This corresponds to a astabld v 22o substantially zero see B at the terminals of the switch 35, The diode with the capacitor form a rectifier negative peaks of the pulses of line return, the capacitor providing a voltage thereacross which astalbe a function of the amplitude negative peak thereof.
In this case, the time t s of the saturated state of the switching transistor 11 and the conductive state of the diode 12 and, therefore, the ratio of this length to that of the full cycle line period T H or the t B of the locked state, are constant and chosen so as to make the peak amplitude of the voltage pulse 19 v, applied to the collector of transistor 11 during the blocking interval t a, substantially less its voltage collector-emitter breakdown in the locked state V CEX which can now exceed volts.
This reference voltage is applied to the base of transistor On the other hand, an overload in the circuits of the television, such as for example a short circuit of the scan transistor TH, resulting in an overcurrent in the diode D and the inductor L.
The control stage 50 includes a phase shifter cascading floor called “phase splitter” in Anglo-American literature and an output stage of the “push-pull series,” often used in integrated logic circuits of the TTL type. These details of construction have no bearing on the operation of the circuit as described above, but only allow an easier adjustment. This current IL becomes from time t2 where it reaches its maximum value IM, decreasing linearly and passes through the first diode D1 in the forward direction for charging the second capacitor C2 and supplied, inter alia, the scanning circuit SH.
Supply device of one of claims 4 through 6, of the type in which the frequency of autonomous operation of the astable multivibrator 48 is higher than the line frequency in order to limit the peak voltage V 19 max at the collector of the chopper transistor 11characterized by the fact that the transistor of the multivibrator 48 the condition of which is complementary to the condition of the chopper transistor 11 is supplied at its base through a diode by a synchronization stage 49 delivering negative pulses the amplitude of which is a predetermined fraction of the amplitude of the line fly-back pulses so as to extend the duration of the blocked condition of this transistor which is intially shorter than the duration of its saturated condition until the sum of these durations is equal to the line period.
If, against, we want to avoid exceeding the collector voltage peak V 19 max start, we choose an autonomous period T 48 A of the multivibrator 48 less than the line period T H 64 microseconds and synchronizes the acting only over the duration of the off state of the first transistor of multivibrator 48, by extending it. Figure 5 is a preferred embodiment of the block diagram of a control circuit 40 of Figure 1 which controls the transistor 11 of the chopper circuit 10, according to the invention.
The difference between the peak values 16 i t 6 and 16 i t 7 in absolute be explained, firstly, by the ohmic losses in the circuit 10 and, secondly, by the transfer of energy between the latter and, mainly, the output stage In Figure 6, the power source 51 of the control circuit 40 nultivibrateur a rectifier circuit 52 of the doubler type voltage alternating comprising two diodesin series. The positive pole P of the input voltage VE source is connected to one terminal of an inductor L energy storage, while its negative terminal N is connected to the ground G of the receiver, which is isolated from the network.
The inductance reduced by the line transformer in the 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. The energy transferred during each line period T H by the switching circuit 10 to the output stage 30 via the transformer 20 can therefore cry: Supply device of one of claims 4 and 5, characterized by the fact that the phase shifting stage 46 comprises a delay generator delivering a saw tooth voltage with recurring teethtriggered by the rising edges of the line fly-back pulses to an analogous voltage comparator stage, supplying negative pulses at its output to the base of that one of transistors of the multivibrator 48 the blocking of which controls the blocking of the chopper transistor 11which occurs at the instants where the momentary amplitude of the saw teeth exceeds a fixed threshold voltage V zand by the fact that the regulating stage 47 comprises a rectifying circuitfor rectifying the signal supplied by the auxiliary winding 25 supplying a signal generatordelivering a signal which, starting from a predetermined threshold, modifies the inclination of the saw teeth as a function of one of the peak amplitudes or the peak-to-peak amplitude of this signal v2s ‘.
This longer delay causes a reduction of the voltage V 33 from the previous cycle where it was too strong, and the next pulse of flyback third will present an amplitude V 25 V 25 N greater than B and less than 25 V F.
Switching regulator power supply device combined with the horizontal deflection circuit of a television receiver which it supplies. During this interval of saturation of the transistor T1 which extends to the leading edge of the next flyback pulse, the energy is stored in inductance L. The collector of transistor T5 is joined to the ground via a resistor R20 of 3.
The control stage 47 also receives the pulses of line return, the recovering and transmits to the control input of the phase shifter 46 a floor should sign shaped current for changing the slope of the saw tooth function of the amplitude of the multivibrateuur pulse which is a function of the DC voltage at the terminals of the supply capacitor 33 Figure 1 of the output stage It is therefore advantageous, when using a core magnetic circuit in rectangular ferrite frame-shapedcoyrs the windings 22, 23 and on one of the legs thereof, and the coil 21 and possibly coil 25, on the cojrs, which also contributes to a good isolation between the primary and secondary masses multivirbateur This voltage continues to control the duration the pulse is obtained with the aid of a rectifier assembly 42 also fed by the first input and having a second diode connected for.
The anode of the diode is connected to that of a zener diode whose cathode is connected to one terminal of a first resistor The other terminal of the winding 22 is connected to one terminal of a third capacitor 33 of high capacity, the other terminal is connected to the junction of deflection coil 31, return capacitor 34, the anode of the second diode 35 and the emitter of the second transistor 36, which is also joined to the body 39 of the chassis of the television receiver, known as “cold” ground because it is isolated from the AC power supply network.
When this circuit does not work, the feed does not work either, but it provides a VSI output voltage value lower than the nominal voltage VS which can not produce damage, and which may, for example, make it possible to powering a watch receiver for television receivers equipped with a remote control.
P BAC Séries
The switching transistor is controlled by a control circuit fed by pulses return line from an auxiliary winding of the line transformer, which triggers a variable delay generator and of which a rectified peak amplitude variation of astale delay control.
Switching regulator power supply device combined with the horizontal deflection circuit of a television receiver which it supplies.
FR Free format text: The regulation is performed by varying the width of the pulses controlling thereof. The control circuit 40 of Figure 4, is supplied at its first input by 25 v t signal provided by one of the terminals of the auxiliary winding 25 which is substantially the inverse of the signal v 21 t shown in the diagrams C respective of figures 2 and 3, where we distinguish during each line period, a pulse of flyback positive polarity and a negative plate whose amplitude is proportional to the DC voltage V 33 across the capacitor This first input supplies, through a first diodethe trigger input of a first monostable rocker 41, variable length producing at its output in response to leading edge of the flyback pulse, a rectangular signal whose duration varies according to a DC voltage applied to its control input of duration.
The other terminal of the inductor L is connected on the one hand, to the collector of a first bipolar switching transistor T1 of the NPN type, whose emitter is connected to ground G, and on the other hand, the anode of a first diode D1 whose cathode is connected to the positive plate of a second filter capacitor C2.
The operation of the chopper circuit 10 powered by the DC voltage V A is in effect similar to that of the output stage 30, except as regards the shape factor which is determined mainly by the respective values of inductance 16 of the choke 14 and the leakage inductance of the winding 21 of the transformer 20 connected in series and the capacity of the tuning capacitor Supply device according to claim 2, characterized in that the regulation by the phase delay between the respective blocking moments is performed as a function either of the peak-to-peak or amplitude ridge during the return or one way of scanning, the signal at the terminals of one of the windings 21 or 25 of the transformer-line 20 by comparing it to a reference voltage and controlling the delay as a function of the difference between the voltage corresponding to one of these amplitudes and the reference voltage, in order to stabilize either the scanning amplitude, or a supply voltage obtained by rectifying the flyback pulse.
The present invention relates to a feed device regulated in combination with the output stage of a scanning-line circuit of a television receiver, can also provide continuous supply voltages to other circuits of celui- above, by cutting a generally DC power supply voltage obtained by rectifying and filtering the AC mains voltage by using a switching circuit. Ceci augmente la tension V 33 et l’amplitude de l’impulsion de retour-ligne.
The diagram C is in the form of wave voltage v 21 t across the power winding 21 when the leakage inductance is negligible, it is obtained by processing the alternating component of the voltage v t.
DE Date of ref document: Figures 4 and 5 illustrate two different embodiments of the driver stage 20 of Figure 3, providing effective blocking of the first transistor T1. In the circuit of Figure 4 of this article was inserted between the collector of the switching transistor and the winding of the transformer, an inductance of microhenry in parallel with a resistor, which together constitute a protection circuit against rates excessive rise of the collector current of this transistor.
The diagram D shows the waveform of the voltage v 19 t across the first switch 15 of the switching circuit 10, that is to say between the juncture 19 thereof with the inductor 16 and the primary mass 8 and the diagram e shows dashed the current i 16 t in the inductor 16, when the output stage 30 is not controlled and in full line 21 the current i t resulting from the superposition in the winding 21 of the current i 16 t to that induced by the coil 22 when the output stage 30 is on.
When the multivibrator 48 and the line oscillator operate autonomously and with frequency differences, this creates a beat because there are random variations in phase between pulses of flyback V t or V 21 t – and the waveform of the pulse voltage V 19 tso that the energy supplied or consumed by the chopper circuit 10 to or from the output stage 30 varies from one cycle to another. In Figure 6, the power source 51 of the control circuit 40 comprises a rectifier circuit 52 of the doubler type voltage alternating comprising two diodesin series.
The transistor T3 becomes conductive when its base current IB consists of the sum of currents 11 and 12 becomes positive. Upon cessation of the pulse of negative feedback, the diode is blocked and the second capacitor is gradually charged through the resistor to a positive voltage V BE of about 0.
One can also apply the waveform – VTL to the input 11 of the modulator 10A.