دارات الخرج الراسي في التلفزيون الملون .. كتاب التلفزيون الملون والعادي

15- 8 Vertical output circuits in color TV:

Vertical Output Transformers:

Some types of vertical output transistor amplifiers use matching transformers - this is necessary when the amplifier impedance is higher than the impedance of the vertical deflection coils, which are low-impedance at a frequency (50 or 60 Hz) and are approximately between
(4, 0 to 20 ohms).

There are many transistor vertical output circuits that do not require matching transformers because of their low impedance, and they are connected to a coil and a capacitor or to a direct connection, as in Figures (15-16), (15-17).

Transformer types:

They can be classified into two categories - isolated transformers and self-transformers.

Isolated transformers:

In which the primary coils are isolated from the secondary - Figure (15-18) and the feed current is connected to them by the R- method, and the main disadvantage of this type is the frequency distortion due to the iron heart of the transformer - and the reverse induction in the deflection coils during the erasure period generates a high-voltage pulse on the coils Primary . Transformation in the step-down transformer weakens the voltage applied to the deflection coils.

Autotransformers:

Figure (15-19) shows a self-contained vertical output transformer, and this transformer guarantees the process of reducing the conversion ratio, but the DC current is not isolated from the secondary - and the deflection coils are connected with the transformer through a capacitor - in the figure, the capacitor C secures the frequency response of the transformer. The feed is connected via C-R - the main advantage of this type of transformer is its low cost.

15-9 Vertical Deflection Files:

These coils generate the magnetic field, the lines of which cross the screen horizontally across the neck of the screen valve, and these coils consist of two coils between them (180) - and they are part of the total deflection coils - when vertical scanning, the magnetic fluid moves the electronic beam up and down the middle of the screen. This depends on the direction of the current and its magnetic coils, and as we mentioned previously, the current wave with the shape of a sawtooth is the one that operates the deflection coils.

In transistor circuits and others, the inductive resistance of the deviation coils
The vertical corresponds to the type of these files. In the first type (Saddle), its self-inductance is about (45) MilliHenry, and its resistance at direct current is about (42 ohms). As for the second type (Toroidal), its induction is about (2) Milli-Henry and its resistance at DC is (1.5 ohms). These values ​​include the two coils connected in series, and in transistor vertical deflection files or those with solid elements. The deflection files are connected to the collector circuit through a capacitor to reserve Direct Current for Files and Components (VDR). (which is the voltage-related resistance) connected at the output of the circuit to protect the transistor from the reverse pulse generated in the deflection coils in the line return period. Figure (15-20).


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