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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Otherwise, the multivibrator 48 is conventionally synchronized by the trigger pulse applied to its input The emitter of the second transistor is met, on the one hand, to the 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.

I Pulsation propre du circuit: 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.

Country of ref document: During the intervals of the scanning go t A, where the switch 35, 36 is closed at time t 1 to time t 3, the current i 31 see A of the deflector varies substantially linearly between the values negative peak at t l and positive at t 3 with a zero crossing at time t 2, when the current i 31 passes from the diode 35 to the transistor 36 to drive previously polarized. It is also noted here that the main advantage of the control by phase shift of one chopping circuit operating at duty ratio and constant frequency, with respect to that by the variation of one of the latter, is constituted by the fact that the peak voltage applied to the collector of the switching transistor, when locked, is based solely on the supply voltage.

Circuit arrangement for generating the high tension for television reproduction tubes. Figure 6 is a block diagram of the preferred embodiment of the control circuit 40, the block diagram has been illustrated in Figure 5.

Electronique – Realisations – Sequenceur

The energy transmitted by the transformer 20 will be approximately equal to the product of the voltage V 21 t and the current i 21 t multiplied by the cosine of the phase angle p, if the fundamental waves are considered at the line frequency 15, Hz. The junction of the cathode of the first diode and the anode of the second is coupled to the first supply terminal 1 through the network, via a coupling capacitor which transmits clurs the rectifier circuit 52 the supply voltage and whose capacity is chosen according to the desired DC voltage falling voltage across this capability of the order of several microfarads provides a rectified and filtered voltage of about 15 volts.


The sum of intervals SA t and t B represents the period of autonomous operation of the T A-flop 48 in the order of 58 microseconds, for example.

This collector current is subtracted from the current charging of the capacitor through the resistorso it results astwble a substantial reduction of the slope of the rise of the voltage V t that occurs between the instants t 4 and t 5.

When the second transistor mltivibrateur multivibrator 48 has switched from its saturated state to its off state, its collector voltage is equal to the stabilized voltage V R and the diode is blocked.

In the mulivibrateur power supply of the output stage device of the multivinrateur circuit to which it is combined according multivbirateur the invention is n longer uses the control by the variation of the internal resistance or the duration of the state saturated switching transistor or by varying the duty cycle of the switching frequency constant.

The other terminal of the first resistor is connected on the one hand via a second resistorto the synchronization input of the astable multivibrator 48 and, on the other hand via a third resistorthe collector of the second transistor of the multivibrator to the pulse negative flyback and thresholded by the Zener diodecan not act on the base of the first transistor during its saturation intervals so as to block the imtempestivement.

The output of the astable multivibrator 48 feeds the input of a driver or controller 50 consisting of an amplifier.

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 those circumstances, the gain is sufficient for not using a discrete T2 driver transistor and directly connect the cathode of diode D3 to T10 base entry. The difference between the peak values 16 i t 6 and 16 coure t courz 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 This current IL becomes from time t2 where it reaches its maximum value IM, decreasing linearly and astxble through the first diode D1 in the forward direction for charging the second capacitor C2 and supplied, inter alia, the scanning circuit SH.

In the switching power supply device according to the preamble, the cutting inductance is no longer constituted by the single second winding of the line transformer, but includes an inductor choke clurs in series with said second winding called “d ‘food”.

In Figure 4, the driver stage 20A cornp makes a third supply inlet 23, e connected to the positive pole P of the source of input voltage VE Unregulated and one of terminals of a first resistor R1 1.

I La continuite du courant i circulant dans la bobine I La continuite de la tension u aux bornes du condensateur3. When the input of the circuit 40 receives a multvibrateur negative flyback, the diode begins to conduct and current causes voltage drops across resistorsin series, which cause the transistor to the blocking in the polarizing negatively. The output 14 of the modulator 10 supplies a first input 21 of the driver stage 20 of the first switching transistor T1, a second input receives the pulses 22 of flyback negative polarity – VTL w nance of rove- first secondary winding B2 of TL-line transformer.


SE Free format text: A supply device combined with a, line scanning circuit of a television receiver, the. The input DC voltage VE which is not regulated, is provided by a bridge rectifier R to four diodes, powered at its input by the secondary multivivrateur of an isolation step-down transformer TS buck, whose primary winding is powered by the AC mains.

Electrocintique Sup

The base of the first transistor T1 is held in its transmitter and to ground G, by means of a fourth resistor R4 multivibrrateur. Lapsed in a contracting state announced via postgrant inform.

The sum of intervals SA t and t B represents the period of autonomous operation of the T A-flop 48 in the order of 58 ps, for example. The control circuit 40 of Figure 4, is supplied at its first input by 25 v t signal provided astablle 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 dours flyback positive polarity and multivibrsteur negative plate whose amplitude is proportional to the DC voltage V 33 across the capacitor This first input supplies, through a first diodemultivbirateur 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.

Method for controlling the energy transfer in a static converter, static energy converter for carrying out such method and electric power supply using such converter. The output of stage phase shifter 46 feeds a first trigger input of an astable multivibrator 48 whose second fours input is fed by the output of the synchronization circuit Figure 10 is the vector diagram of the stage controller 30 of FIG control circuit 3. The diagram C is the form wave 21 of the voltage v 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.