منظم + ۱۱۰ فولت .. كتاب التلفزيون الملون والعادي

12 - 13 regulator + 110 volts:

This regulator works on the switching method. It has been mentioned previously, but we will mention the most important points in it using the simplified chart (Fig. 12-18).
We have found that this type of organization saves a lot of energy consumption for a device
future television.

Working principle :

Its work is similar to the work of an electronic switch - it closes and opens the +B feed on the load - and the load is the horizontal output stage Q401, so the filter capacitor Cool stores the pulse energy and supplies it to the load at the specified moment and at a fixed rate.

In the diagram (12-19) this switch is a thyristor (SCR), and for simplicity we consider it a switch S - when this switch is closed, voltage +B is applied to the load - and it is noted that the load current must pass through the induction coil L402 and it consists of Lao2 and C401 Parallel Resonant Circuit - This circuit represents a series impedance of the unregulated voltage of 150 volts, and as a result, the current through the capacitor C401 (and the voltage at both ends) can increase at a rate specified according to L402.

This regulator is a closed circuit - note the connection between the switch S and the regulator setting circuit characterized by the voltage sense (Voltage Sense), when the load voltage reaches (+110 volts).

The voltage sensor senses that. The circuit breaker opens until the sensor detects that the voltage has decreased, so the circuit breaker (s) is closed again and the capacitor Cao is charged to (110) volts. In this way, the voltage remains constant at +110 volts.

SCR thyristor work:

The thyristor is the one that performs the electronic circuit breaker. It is noted that the horizontal output transformer files are in sequence with the L402 file and the SCR401 thyristor elevator. The thyristor is turned ON by the gate pulse coming from the regulator control circuit to the catalytic converter I1.

When the thyristor is closed, it can only open when the anode current becomes zero. This is what happens during the return period of the horizontal line by applying a pulse of its peak (300 volts) to the elevator, and as the figure shows, this is the function of the switch s (opening - closing).

14- 12 SCR thyristor regulation:

The longer the SCR401 thyristor is closed - the higher the output voltage of the regulator. If the thyristor is closed for a shorter time, the voltage of the regulator output will decrease - and thus the voltage of the regulator is adjusted by changing the closing time of the thyristor - and this is what is done in the regulator control circuit.

It should be noted that the thyristor turns off (On) after starting each horizontal line - and opens (OFF) in the pulse of the horizontal transformer, during the line return period. In addition, the time constant of the capacitor C401 is significantly longer than the time of one horizontal cycle. As a result, the number of horizontal turns must occur for each recharge of capacitor C401.

12-15 (Drived Voltages):

Figure (20-12) shows the simplified diagram of the derived sub-voltages, which are:


1 - Screen valve elevator voltage (9 kV) and its triple multiplier + 27 kV).

2 - Variable Focus Voltage (kV to +5kV)

3- Screen electrode voltage (1200 V).

4 - Voltage of heating the screen valve with a horizontal pulse (6.3 volts).

E - (- 40 F, + 210 F, + 27 F).

Derived Sub-Efforts Functions:

_ Elevator voltage: It is about (27 kV) after doubling its voltage three times - and it reaches the screen valve elevator to secure the required date for the electronic beam.

Focus voltage: It is obtained from the first stage of the triple voltage multiplier. One end of this voltage is applied to the focus control, and the other end is connected to the point (1200) volts. q) In the focus electrode in the screen valve.


_ Screen voltage: It is about (1200 volts) and usually appears through the capacitor C419.

_ Heater voltage: It comes from the horizontal pulses from an independent secondary coil in the horizontal output transformer, with a voltage equivalent to (63) volts AC, and is applied to the heating filament in the screen valve.

Note: The AC voltmeter cannot measure 6.3 VAC because it is a pulse voltage.


​​​​​​​​