TV power management. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Телевидение

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The modes of standby operation of the TV and turning it off when watching programs, which are provided by the device considered in the article, differ from those commonly used in economy, convenience, simplicity and reliability. This not only prolongs the life of the kinescope and, therefore, the TV as a whole, but also allows you to get other benefits.

The system is designed to increase the service life of the TV, mainly as a result of saving its most expensive part - the kinescope. It allows you to more conveniently, pleasantly and safely handle such a household appliance.

The device ensures that the kinescope filament heating mode is switched on when moving objects are detected in the room ("auto-heating") and periodically "questions" the viewer about the need for further operation of the TV ("auto-sleep"). An additional function of the system, implemented when the TV is turned off, can be work as a security alarm system.

The criterion for the need to turn on the TV is the appearance or movement of a person within the room. The operation of the system is based on registration of changes introduced into the interference distribution of IR waves in the room by moving objects. Having detected such changes, it turns on the on-duty heating of the kinescope filament, goes into standby mode for about 30 seconds and then, if no more actions are taken, turns it off.

The "auto-heating" mode has a number of advantages over the widely used method of continuous on-duty heating of the TV kinescope filament. Firstly, this is an order of magnitude lower average time consumption of electricity, secondly, the absence of evaporation of the kinescope cathode material during waiting, and, thirdly, significantly greater electrical and fire safety during operation. In addition, the system is guaranteed to remove the "syndrome of the TV left on".

The "auto-sleep" function, due to the specifics of the system, is implemented very simply. At certain intervals, she interrogates viewers by flashing the LED on the front panel about the need for further operation of the TV. In this case, it is quite enough just to wave your hand, that is, to trigger the infrared IR sensor, and the TV will continue to show. Obviously, this is more convenient than actions provided by similar systems, such as pressing a button, switching channels, etc. If the system does not receive a response, after about 10 minutes the TV will be disconnected from the network and the system will go into standby mode.

Such a system already works with the Rubin-Ts281 TV (ZUSST), but can also be installed on TVs of other models.

The schematic diagram of the device is shown in fig. 1. It uses a remote IR sensor SRP-100 with typical settings, but any other sensor can be used, as long as the necessary sensitivity and method of inclusion in the system are provided (closed relay contacts in the initial state).

(click to enlarge)

The sensor, the nodes for turning on the kinescope filament and supplying power to the TV are connected to an unstabilized source assembled on a transformer T1, diodes VD10 - VD13 and capacitor C4. The filament circuit of the kinescope itself is connected to the winding 7 - 8 of the transformer T1 through the triac VS1, the switching on of which via the bridge on diodes VD6 - VD9 is controlled by the optocoupler U1 of the kinescope filament switch-on unit. The latter is assembled on a VT1 transistor and a DA1 timer according to the pulse suppression detector circuit described in the book by Pukhalsky G. I., Novoseltseva T. Ya. "Designing discrete devices on integrated circuits" (M .: Radio and communication, 1990).

In the initial state, the relay contacts of the IR sensor K1.1 are closed, the transistor VT1 is closed, the capacitor C2 is charged to a voltage exceeding the switching threshold of the timer DA1, and its output is at level 0. The system is in standby mode.

When the IR sensor is triggered, the contacts K1.1 of its relay open, the transistor opens, the capacitor C2 quickly discharges through the diode VD1 and the transistor VT1 and the output of the timer DA1 will be level 1 until the capacitor C2 is charged again to the switching threshold of the timer for a waiting time of about 30 s . The appearance of level 1 at the output of the timer DA1 causes the opening of the optocoupler U1, the triac VS1 and the connection of the kinescope filament circuit to the filament winding of the transformer T1. LED HL1 signals the inclusion of heat.

If during the waiting time the TV is turned on, +3 V voltage will be supplied to the anode of the VD15 diode from pin 4 of connector X2 of the MPZ-3 power supply module of the TV. Although the diode VD2 will close with reverse voltage, the control current will still flow through the diode VD3 and the optocoupler U1 and the triac VS1 will remain in the open state. Further switching of the timer will not affect the state of the system.

During the waiting time when the TV is turned off, the sensor may be triggered again. As a result, the DA1 timer will restart again, starting a new countdown. If no action is taken during the waiting time, the timer will return to the zero state, the heating circuit will be de-energized and the system will go into standby mode.

When you turn on the TV, the auto sleep mode node starts to work. It contains a counter on DD1-DD3 chips, a DD4.1 D-trigger, a TV power control unit (VT2, K2) and an alarm unit (VT3, VT4, HL2).

The TV turns on when you press the SB1 button (1 ... 2 s). At the same time, transistor VT2 opens, relay K2 is activated and connects the TV power supply module to the network with its contacts, a +12 V supply voltage appears in the TV (pin 7 of the X2 connector of the power module), supplied to the counter and trigger. The counter and trigger DD4.1 are set to zero at the inputs R due to the inevitable operation of the sensor and the opening of contacts K1.1 during manipulations in the immediate vicinity of the TV.

Level 2 is present at pin 4.1 of the DD1 trigger, therefore, even after the SB1 button is released, the VT2 transistor remains open and the K2 relay contacts are closed. At the input C (output 1) of the counter DD1, frame pulses KSI with an amplitude of 10 V begin to arrive from pin 8 of the X8 connector of the MRK2-5 radio channel module, which are used as counting pulses for the counter.

Provided that the sensor contacts remain closed, i.e., it does not operate, after about 45 minutes (the exact value is not significant), level 32 will appear at output 12 (pin 3) of the counter DD1, which is fed to the input D of the trigger DD4.1.

This opens the transistor VT4 and the LED HL2 starts flashing with a frequency determined by the appearance of pulses at the output 16 (pin 11) of the counter DD1 (about 1,5 Hz) and the opening of the transistor VT3 caused by them. This indicates that the device is ready to turn off the TV.

After about 10 more minutes, a positive voltage drop that occurs at output 8 (pin 10) of the counter DD3 will cause the trigger DD4.1 to switch, the level 0 will appear at its output and the transistor VT2 will close. The TV will turn off. The decay of the pulse at input D (pin 5) of the trigger DD4.1 has some delay relative to the voltage drop at its input C (pin 3), so the trigger switches steadily.

If during the time preceding the switching, the IR sensor is triggered, the counter will be reset and the time will start again. It should be noted that it is mandatory to use resistors R2 and R4, which limit the current through the inputs of microcircuits.

The adjustment of the device begins with setting the desired waiting time, i.e. maintaining the cathode of the kinescope in a heated state, by selecting the timing capacitor C2 and resistor R8 (no more than 1 MΩ). Care should be taken to keep the leakage resistance of the capacitor as low as possible.

Before connecting to a kinescope, it is necessary to make sure that the filament voltage corresponds to the nominal value, since due to the phase shift when the triac is turned on, the effective value of the voltage supplied to the heater is less than the voltage taken from the transformer winding. The inclusion of the windings in the primary circuit of the transformer T1, shown in the diagram, is made taking into account this fact. The voltage is checked on a load equivalent, for example, on an electron lamp heater with a filament current that is close in value to the filament current of the kinescope used. If necessary, the deviation is eliminated by switching the outputs 4, 4a, 4b of the primary windings of the transformer. Changes in the standby power supply voltage of the device that occur in this case are within acceptable limits and do not have a noticeable effect on the operation of the system.

The IR sensor can be called the most important and responsible part of the system. The SRP-100 used in the device has the following main characteristics: the recorded object movement speed is 0,15...3,6 m/s; pulse repetition period - 50, 150, 300 ms (set by the manufacturer or user, depending on the conditions of use); viewing angle in the horizontal plane - 105°; maximum range - 20 m; supply voltage - 7,8 ... 16 V; current consumption in standby mode - 14 mA, in active mode with operation indication - 8 mA; for connection to external devices it has normally closed relay contacts.

The sensor (made in Israel) is widely used in fire and security systems (the so-called "volume sensor") both in Uzbekistan and in Russia. It can be purchased at any organization specializing in such systems, for example, at the Rakhm-Shavkat CBR (700185, Uzbekistan, Tashkent, Chilanzar district, Nakkoshlyk street, 2).

The possibility of using a similar or different sensor is determined by its main parameters, the desire and capabilities of the user.

In the device, instead of a D-flip-flop from the K176TM1 chip, a trigger from K561TM2, K176TM2 is applicable. Other microcircuits of the CMOS structure can also be used in the counter, it is only important to obtain the necessary signals for the operation of the system, and the time intervals can be changed at the request of the user.

In addition to those indicated in the diagram, transistors from the KT3102, KT361, KT315 series with any other letter indices or similar ones with parameters no worse than those used can be used.

All resistors are MLT. Capacitor C2 - K53-1, the rest oxide - K50-6, K50-16, C1 - any small-sized ceramic capacitor with a capacity of 6800 pF ... 0,068 μF. Diodes - any of the KD503, KD509, KD521, KD522 series, bridges - from the KTs402, KTs405 series or assembled on the diodes listed above. Optocoupler and triac - from the AOU103 and KU208 series, respectively, with any other letter index. Relay K2 - RES22 passports RF4.523.023-01, RF4.523.023-05. LED HL1 - AL307A (M), AL307B (M), HL2 - from the AL307 series of yellow, orange or green glow. Transformer T1 - TN36 -127/220-50.

Structurally, the standby power transformer T1 is best installed on the side wall of the TV above the control unit. Next to it, the circuit boards of individual modules are fixed with the units of standby heating ("auto-heating"), "auto-sleep" and a rectifier. A different location is not recommended, since a rather massive transformer placed elsewhere will affect the purity of the image color, and the CMOS counter structure chips will be closer to the horizontal scanner, which is undesirable. In addition, it is more convenient to connect power circuits and remove the signal from the radio channel module (CSI).

The LEDs are located in the holes in the upper right corner of the front panel, the buttons are on the same panel near the standard switch.

The IR sensor, as already mentioned, is a separate remote unit connected to the system with three twisted wires (power, common and signal) 120 cm long. depends on the lens used in it, the radiation pattern in both planes, the relative position of the TV, furniture, absorbing surfaces and doorways in the room, as well as the presence of animals in the house. General recommendations should be to place the sensor at human height, on a vertical surface, so that the main axis is directed towards the doorway.

It should be noted that although the described system has been working reliably for about two years, it has a well-known drawback, which consists in jumping the rated voltage in the kinescope filament circuit, which is especially unfavorable when turned on. To eliminate this shortcoming, a kinescope filament power supply module is proposed, the schematic diagram of which is shown in Fig. 2. In this case, the triac VS1 is removed from the device, and the same control optocoupler U1, a bridge on diodes VD6 - VD9 (another series) and a resistor R15 (with a changed rating) are used in the power module. Positional designations of new elements continue the numbering of parts of the main device.

The module uses optocoupler control to provide electrical isolation of the heating circuit, as well as some unification of the inclusion of possible options for such modules.

The kinescope filament power supply module provides a smooth increase in the filament voltage and its stabilization, which contributes to an additional increase in the kinescope's service life. The module has the following main characteristics: rated filament voltage - 6,3 V (DC), rated current - 0,7 A, maximum current - 1,2 A, filament voltage rise time to the level of 0,9 nominal value - 3 s.

The module is assembled according to the stabilizer circuit on the op-amp (DA2) with a modified switching method. It uses direct control of the op amp with OOS, i.e., the VT5R15R16 reference voltage generation circuit is connected to the input of the stabilizer. This made it possible to most simply implement a smooth increase in the output voltage by adding capacitor C6 with a slight decrease in the stabilization coefficient, but quite sufficient to power the heating circuit.

The reference level is formed at the reverse biased emitter junction of the transistor VT5, operating at low currents.

When a control signal is received from the output of the timer DA1 of the main device and the optocoupler U1 is opened, the capacitor C6 begins to charge to the reference voltage. The output voltage increases as the capacitor charges, after which the stabilizer enters the operating mode.

Resistor R17 serves to linearize the output characteristic in the region of low voltages. When adjusting it by selection, the initial filament current of the kinescope is set (in the absence of a timer control signal) within 20 ... 50 mA. Trimmer resistor R19 sets the exact value of the output voltage of 6,3 V.

When choosing a VT5 transistor from the KT315 series, it should be taken into account that the reversible breakdown voltage of its emitter junction should not exceed 6,7 V, which makes it possible to achieve the optimal control characteristic, taking into account the voltage drop at the emitter junction of the VT6 transistor. If this condition cannot be met, you can select a transistor from the KT316 series with any letter index (their reversible breakdown voltage obviously lies in the desired range).

The voltage of +9 V at the input of the stabilizer, if necessary, is set, as in the variant with a triac, the glow voltage is switched by switching taps 4, 4a, 46 of the primary winding of the transformer T1 of the standby power supply.

Transistor VT6 must be installed on the heat sink.

Diodes VD6 - VD9, in addition to those indicated, you can use others from the KD213, KD202 series with any letter index. Transistor KT972A (VT6) will be replaced by KT972B.

OU K538UN1 can be replaced by K548UN1 - one channel, for example, connect the exemplary voltage generation circuit to pin 1, the R19 resistor slider to pin 2; the output will be pin 7; the positive power conductor is connected to pin 9, the negative to pin 4; correction capacitor C7 is connected between terminals 5 and 6.

Author: D. Pankratiev, Tashkent, Uzbekistan

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