استخدام العناصر الصلبة في دارت التلفزيون الأحادي الون . كتاب التلفزيون الملون والعادي

17- 8 The use of magnetic elements in monochrome television circuits:

In this, we will explain the chapter explaining the horizontal and high-voltage output circuit, transistors, and integrated circuit shifts. As for the SCR thyristor circuits, another hero, we will study them later. The special requirements for monochrome devices for this stage are:

1- Transistors that communicate with a large current, with great speed in cutting and connecting.

2 - Transistors with overcurrent and voltage protection.

3 - The shape of the stimulus wave is rectangular and not trapezoidal.

4 - The output transistor protection must be biased, in case the catalyst stops working.


It was the realization of the first item, especially in the large size until the year (1960), when the great development that took place enabled the use of transistors in the horizontal output stage, and the picture became on the cut and connect with a peak power of up to (2000) watts or more. Dissipated internal power equal to (1 watt) - Silicon elements are used extensively in this field, as they are pretty high and fast in cutting and joining.

The large tolerances of the output transistor can be switched off, and the overvoltage and overcurrent warnings. One of the ways to protect and reduce the overshoot voltage in the collector of the output amplifier transistor, which is shown in Figure (8-17): The reverse peak voltage that appears on the collector during the reverberation period reduces the third sequence of the sine wave of the pulse (15625) Hz - and the third harmonic is a parallel composing circuit, which is Part of a high voltage circuit. Figure B shows how the original pulse combines with its third harmonic to reduce the pulse size.

Over current protection:

The method regarding overcurrent protection of the output transistor is shown in Fig
(9 - 17) - Transistor 2 is the horizontal output transistor and 02 is a current transistor. Both are in series between voltage (30) and earth. The current through 2, the current through the connected current 02 is determined by the activities resistance R and that the current rate in the connected current. and the current pulsating through 2 due to the horizontal oscillator is constrained within a rate set by (02)

Determining the location of the output transistor by controlling the base shape, and the voltage of the base wave, east, east, shown by (10-17) and this shows the typical form of operation of both shapes are similar at first sight. But they differ in the ratio of the time of cutting and connecting. In the first, the operating figure is (0.64 / 1.1) in the figure and is equal to 1.7, while at the time you invest in the operating time conversion, which can be converted into the output transistor current - and in this way determine the electrical power draw. Output transistor protection

The rectangular wave in the base command:

It is one of the requirements for using transistors in the horizontal output amplifiers - and the rectangular wave as in Figure (10-17) differs greatly from the trapezoidal wave used in the horizontal output amplifier valve network. The output transistor is occupied by low voltage - large current in the transformer and deflection coils - and these deflection coils have high inductive resistance compared to their ohmic resistance, therefore a rectangular voltage pulse is required.

Shutdown protection:

This is one of the requirements for the use of the transistor in the horizontal output amplifiers - where the transistor must be protected when the horizontal oscillator stops working - the output transistor is biased so that no current passes through it except when the signal pulse is applied to its base, and if the operation stops, there are no pulses that operate it and it does not disperse inside it, i.e. capacity, so it shuts down completely when it fails to operate.
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