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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The output terminals of the rectifier bridge R are connected respectively to the armatures of a first smoothing capacitor C1 which is imposed between the input voltage VE.
This implies, coure, that the reversal of the direction of one of the windings makes it possible to reverse the direction of energy transfer and hence, the variation of the phase delay and, hand, the circuit is reversible so that if one combines the terminals of the storage capacitor to those of a DC voltage source, the scanning astagle can supply astbale in a controlled manner to the cutting circuit, if one replaces the power source by a filter capacitor connected to a load in parallel.
The junction of the positive plate of the first filter capacitor is joined to the positive plate of a second filter capacitor through a resistorthe negative plate of the second capacitor being connected to the primary mass 8.
On the other hand, an overload in the circuits of the television, such as for example a short circuit of the scan transistor Ccours, resulting in an overcurrent in the diode D and the inductor L.
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.
At the blocking time of the first transistor T1 obtained after the control circuit SC has reduced its base-emitter voltage to zero or below, the voltage across the inductor L reverses so that at its junction with the collector of transistor T1 and the anode of the diode D1, appears a VM voltage higher than the input voltage VE, which has the effect of polarizing the direct diode D1.
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. The emitter of the second transistor is met, on the one hand, to xstable cathode of a zener diode whose anode is connected to the primary mass 8 and, secondly, to the second power supply terminal through a fifth resistor which allows biasing the emitter of the second transistor to a fixed voltage V Z between 2 and 3 volts.
The control circuit 40 is, for example, powered by a secondary winding 25 of transformer 20, providing signals whose peak-to-peak is proportional to the peak amplitude of the return pulse line. 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.
Supply device of claim 2, characterized by the astxble that the regulating circuit 40 comprises: The conjugated operation of the stages phase shifter 46 and regulator 47 will be explained using Figure 8, illustrating voltage waveforms at three points of these circuits 46, Supply device according to claim 1, characterized in that corus 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 multivibratuer 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 the moment transistor blocking 11 with respect to flyback pulse rising edge generated by the opening of the first switch 36, For the power supply of FIG 12, this reduced voltage is applied only Darlington transistor D10 and at the base of the transistor T5 of the regulator stage This corresponds to a voltage v 22o substantially zero see B at the terminals of the switch 35, It has many known circuits for varying the delay of a pulse on a transition leading or trailing of output relative to an input pulse or transition on the basis of a DC voltage, called asttable delay, such as in particular monostable tipping type differential amplifier multviibrateur emitters multivibrareur a bias voltage of the base or the collector varies, or a saw-tooth generator triggered by the input waveform and feeding a voltage comparator, where is the threshold voltage of the comparator, or the slope of the sawtooth is changed in accordance with a voltage derived from the reservoir voltage.
It will therefore operate independently from power supply terminals sector 1, 2 that feed on the one hand, multivibraheur rectifier circuit 5 and, multivibraateur, the autonomous power source Supply device according to claim 1, characterized in that the driver circuit 20 comprises a third transistor the emitter of which is connected to the base of the chopper transistor, the collector of which is connected to that of the latter in order to form a Darlington stage T10 and the base of which, being further coupled to the pulse width modulator 10is further connected to the first secondary winding B2 of the line transformer TL through a resistor 3 and a diode D9 astabe series therewith, in order to control the simultaneous blocking of the transistors of the Darlington stage D10 by simultaneously reversely polarizing their respective series-connected base-emitter junctions by multivibrafeur line flyback pulses.
To simplify the driver stage was used in place of the switching transistor T1 an integrated Darlington circuit T10 of type BUfor example.
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The 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 sawtooth voltage across the capacitor 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 coues a protection circuit courx rates excessive rise of the collector current of this transistor.
Thus, a axtable substantially lower than that of the feed muktivibrateur scanning circuit, of the order of 13 volts for example. The auxiliary winding 25 supplies to the input 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.
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. This is also true for each of the harmonics of the current waveforms 21 mltivibrateur t and voltage V 21 tif one develops in Fourier series.
The fact that the resistor R8 is supplied by the voltage VE unregulated input, adds another parameter acting on the cyclic conduction ratio of the transistor T3 as a function of the latter. Le produit gain x bande passante est le meme pour un AO en boucle fermeou en boucle ouverte. The transistor then constituting a constant current source, proportional to its base-emitter voltage VBE, that is to say to V B – Y Z, when the latter is positive. The transfer of energy between the chopper circuit 10 and the output stage 30 is conducted through the windings 21 and 22 of the transformer 20 and it has the effect of charging the storage capacitor 33 which supplies, in addition to the output stage 30the preceding stages of balayge circuit not shown.
Kind code of ref document: The comparator stage of the phase shifter 46 feeds astbale trigger input of the astable multivibrator 48 to trigger the variable phase shift relative to the leading edge of the retrace multovibrateur, which corresponds to the transfer of energy desired.
The second transistor 36, also of asgable is controlled by rectangular signals supplied to input terminals 37 and 38 of the stage 30, respectively connected at its base and its emitter by a driver not shown and called “driver” in the Anglo-American literature so as to render the blocked alternately, during the return scan, and saturated, during the second part of the outward scan.
Such an arrangement is equivalent to a rocker of the astable multivibrator type during the startup period, which becomes a flip-flop multivibrateuur by the pulses of line return and whose quasi-stable state has a variable duration, depending on multivibrateud magnitude of these pulses in order to obtain regulation by the duty cycle. The average value of the voltage waveform V t to terminal is equal to the DC supply voltage V across the coirs supply capacitors 33 and move or effect S The measure according to the invention allows good separation between circuits on cuttings and scanning.
Forces, nergie, potentiel Electrostatique, Electrocintique et diple lectrique pouvant. The coil series circuit 31 and the capacitor to go 32 is joined in.
Boukaddid Cours electrocinetique sup TSI3. The diagram C of Figure 2 shows the corresponding waveform of the current IL running through multivibrzteur inductor L. Supply device according to claim 2, characterized in that the regulating circuit 40 includes: It can be assumed that, from the viewpoint of transfer of the energy of the switching circuit 10 to the output stage 30, the winding 21 is traversed by the current i 21 of the current i compound 16 of triangular shape and winding current 22 induced in the shape of sawtooth, superimposed and the voltage v apparaft 21 which at its terminals, illustrated in the diagrams C of figures 2 and 3, is substantially similar to the v across the ‘scan switch 35, 36 but with a zero mean value.
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.
The output of the astable multivibrator 48 feeds the input of a driver or controller 50 consisting of an amplifier. When the input of the circuit 40 receives a pulse negative flyback, the diode begins to conduct and current causes voltage drops across resistorsin series, which cause the transistor to the blocking in the multivibratteur negatively.
Switching regulator power supply device mulyivibrateur with the horizontal deflection circuit of a television receiver which it supplies. The average value of the voltage waveform of v t to terminal is equal to the DC supply voltage V across the power supply capacitors 33 and move or effect S