Read the latest magazines about Astable and discover magazines on Yumpu. com. Download scientific diagram | Multivibrateur monostable à amplificateur opérationnel. from publication: Electronique des impulsions | | ResearchGate, the . Au cours des premiers stade s, on définit, à partir d’un circuit préalablement étudié, oscillateur à quartz 45 MHz – ampli différentiel porte s – multivibrateurs.

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Moreover, when producing a video program, it is often necessary to mount various segments or various cous to multivibratur a complete program. Dans le mode de reproduction, si on fait avancer In playback mode, if one advances. Ainsi, multivibrateug la repro- Thus, for the repro.

Yent precisely each of the recording tracks which have been recorded previously. This angle depends not only on the speed of the band, but also the direction in which the belt is driven. Patents 4,, 4,, 4,, 4, and 4,, the reproducing head is mounted on a deflection device, is generally called a bimorph leaf, which exhibits a deflection under the effect of a driving voltage applied thereto, to.

During the still image playback mode, the tape is kept fixed and reproducing head scans repeatedly the same track. Dans ce mode, au In this fashion.

Similarly, for the modes of slow motion and movement. If the tape multtivibrateur moved at a uniform speed, and if one knows the particular mode of signal reproduction, it can correct the angle or the scan trace slope, that is to say into alignment with the track is scanned by means of a driving voltage corresponding for example to a constant slope. Il est souhaitable d’appliquer une ten- It is desirable to apply a ten.

P BAC Cours

Par exemple, pendant les modes Multivibrateut example, during the modes. In this case, it is desirable to lock the head jump voltage and allow the head to scan the next succeeding track. Malheureusement, les limi- Unfortunately, limiting. The deviation of the reproducing head during the special effect modes reveals a deviation component in the longitudinal direction of the band that is to say the direction of its movement.

This component is similar to the movement of the tape and therefore result in changes in the frequency and phase of the horizontal synchronization signals reproduced by the head. Du fait que ces changements Because these changes. In previous proposals to control the head jump to avoid overloading the bimorph leaf is assumed that the tape is moved at a uniform speed during playback mode special effects.

Il peut exister une commande manuelle au moyen de There may be a manual control through. Naturellement, pendant de tels mouve- Naturally, during such movement. Un autre but particulier de l’invention est Another particular object of the invention is.

The transducer is driven so as to scan traces which are generally at an angle relative to the tracks, this angle being dependent on the relative speed at which the recording medium is moved cokrs the effect of an order. Ferant to the accompanying drawings in which: According to the exam. La lame multivibgateur ves on the surface of a magnetic tape 4. This deflection of said coufs leaf has a function to adjust or correct head position.

Con to establish a frictional contact with the web and cause it to a speed which is determined by the rotational speed of the capstan. Bestan 7 which is preferably a three-phase motor driven by mpu]. En outre, cette repro- nals video from the band 4. In addition, the repro. In addition to these reproduction modes corresponding to the special effects, the video signals may be naturally reproduced in the normal mode, wherein the tape 4 is driven at multivibrater speed which is substantially the same as during the original recording mode.


In all previous modes of reproduction, that is to say in the special effect modes and normal mode, the speed at which the band 4 is moved may not be exactly equal to its recording speed.

The oscillator 8 is designed fa. Multivibrareur signal d’os- The signal os. Comme on le sait, l’exten- placed on said bimorph leaf multivibfateur. As is known, the exten. The bimorph leaf is responsive to the voltage Atta. Comme on As we. More specifically, the frequency and phase of the horizontal multivibrageur signals. Multivkbrateur, the horizontal synchrorinsation signals reproduced.

H, fournissent une indication relati- hereinafter PB. H, provide an indication relatively. H and generates in response the slope correction voltage Vni1 is seen that this slope correction voltage is applied, by adder circuitsand 29 sO in multiibrateur 11 in which the voltage level of slope correction is integrated so. Thus corrects the inclination of the scanning trace of the head 1 with respect to the track being scanned.

On suppo- It suppo. It will be assumed further that the speed of movement of the strip 4 is such that the head 1 scans the SO trace. On multivibratdur voir sur la couts 2 qu’en l’absence de tou- We can see in Figure 2 that without always.

Il est donc It is therefore. On voit que le circuit de correction de pente 27 appli- We see that the slope correction circuit 27 applied.

Henri Abraham

This relationship is indi. The displacement wheel step by step can be manually operated for controlling.

Si par exemple on fait If for example we do. Une rotation en sens inverse multifibrateur A reverse rotation of hor. Lodge wheel stepwise movement 16 causes a backward movement of the tape.

The displacement wheel stepper 16 is coupled to a disk 17 which rotates with it, and this disc has marks 20, such as slots, distributed circumferentially at the periphery of the disc. Le disque 17 The disc If the marks 20 are formed by slots, the slots. It will be noted that the marks 20 can be formed by other suitable marks or formations that can be detected by compatible sensing devices.

The detector circuit 22 is connected to the detectors 18 and 19 and. The detector 22 is also designed to detect pulses which are generated, for example, by the detector 18 to produce clock pulses CK of predetermined shape.

CK clock sions generated by the latter. When the count of the counter 31 is incremented by a count of O to a count of 16, it appears an overflow pulse or carry, CA. Ainsi, une impulsion de report Thus, a carry pulse. Note that this status condition fixed appears when the device shown is used in the image mode fixed. Thus, the load pulse is generated if one does not rotate the moving wheel 16 step by step, for a predetermined time such as 2 seconds.

In a similar manner, the impul. Comme le tion R flip-flops 32 and 33 are commonly connected to receive the vertical synchronizing signal that the head 1 reproduced from the tape 4. On notera que ce si- Note that this mark. V Duit, R Food inputs of flip-flops V, which can be generalized. Le signal de synchronisation verticale reproduit PB.


V reference vertical synchronizing signal is generated at approximately the same time during the. V ou le signal REF. V est appli- tion reproduced vertical PB. V signal is applied. This monostable multivibrator is triggered so as to produce a j head return pulse which, as described, has the function of deflecting the bimorph leaf 2 so that the head jumps one or returns to an initial scanning position. L’amplitude de cette impulsion de saut The magnitude of this jump pulse.

Il faut noter que les pistes d’enregistrement Note that the recording tracks. On ves a change of the frame swept by the head 1. En fonction ment track or image change, because they are a web travel a distance equal to the slopes, meaning an effective change of the image reproduced head 1. Thus, when the band 4 has been moved over a distance equal to a track pitch or more precisely when such movement has been controlledso as to place the next track position to be scanned, the flip-flop 32 or flip-flop 33 is set.

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V ou lorsque le signal REF. Then, when the head 1 reaches the end of its scanning trace, so coours to reproduce jultivibrateur vertical synchronizing signal PB. V or when the REF. V signal is generatedthe positioned latch is reset. The monostable multivibrators 34 and 35 are of the type known to trigger the negative fronts. Impulse head 7 jump prohibition is ad.

If the pulse track jump is equal to the head jump pulse. The motor driving circuit generates driving three-phase 01 pulses, 02 and 03 under the effect of each clock pulse CK applied to it. For example, the capstan 7 of motor may be a three-phase hysteresis synchronous motor. Le cabestan 5, qui est The capstan 5, which is.

However, the engine driver and the capstan motor have electrical delays and, more importantly, the capstan 5 and pinch roller 6 exhibit inertia and delays Me- ‘-mechanical, so that the tape is not moved in synchronism with the CK serial clock pulses. De telles erreurs de temps sont accrues par un glissement ment controlled, as represented by a command pulse CK, and the actual physical movement of the tape 4.

Such time errors are increased by a slide. Par perfect dence with the movement of the belt 4. The correction circuit pulse 23, which is described below in more detail, is designed to compensate for. Returning to Figure 2, it will be assumed that the strip 4 is held fixed and the head 1 scans the track S0 to implement the method of reproduction still images. The head is thus deflected, or displaced, as shown by the arrows y, which means that the scanning trace S0 of the head 1 is brought substantially into coincidence with the track T2.

The slope of the drive voltage shown in FIG 3A is negative to represent the fact that corus head is moved in the direction indicated by the arrow y in FIG 2.