Dialogue timer-machine. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Телевидение

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Automatic switches at the end of television programs and timers for a given time in modern TVs are not always convenient for users. And in old TVs they are not at all. Therefore, some radio amateurs use the self-contained time delay devices developed by them, operating in an on-line mode. We are publishing a description of another of the options for such automatic timers.

Many modern TVs use special devices that automatically disconnect them from the network at the end of the program guide (signal loss) on the selected channel. In addition, such devices also use timers programmed from the remote control, which turn off the TVs at pre-selected intervals. However, they do not always suit viewers. For example, you urgently needed to leave the house, and in a hurry you did not turn off the TV, and the timer was not set for a certain period of time. Another example - during the transmission you fell asleep without turning on the timer, and the TV is on a XNUMX-hour channel. In the first case, it will work until you arrive, and in the second - until you wake up, which, of course, is not safe.

The automatic timer proposed for repetition is based on the principle of "dialogue" with the user, similar to how it was done in [1]. The machine is an autonomous unit, which is supplied with mains voltage. The device is located near the place where the viewer is watching the program. Since the distance to the screen can reach several meters, the TV is connected to the machine with a network extension cable of the required length. Intervention in the nodes of the device is not required. It is important only after connecting to the timer to turn the TV network switch to the "On" position. Subsequent switching on or off of the device will be provided by a timer.

After a certain period of time, selected from a number of optimal, according to the author, suitable intervals for watching certain programs, the device beeps, as if asking the user whether it is still necessary to keep the TV on. At the same time, this signal warns that the device will soon be disconnected from the network. If you want to continue watching the program, the viewer needs to briefly press the "Repeat" button during the sound signal, and the machine will again start counting the previously set shutter speed. If it no longer suits the owner of the TV, it should be changed with the "Interval" switch and then press the "Repeat" button again. In the absence of this command, the timer will disconnect the device from the network and turn itself off.

The automatic machine provides switching of loading with power up to 1 kW. The current consumed by the timer from the power supply in the hold mode is 70 mA, and in the sound signal mode it is 90 mA. The device is designed for time intervals of 15, 30. 45, 60. 90 and 120 minutes. The timer can be used not only with a TV, but also with other electrical appliances.

Schematic diagram of the timer is shown in fig. 1. Its simplicity is mainly due to the use of the KR512PS10 microcircuit, which is a device with a variable frequency division factor and is intended for use as a delay element in a time relay [2–5].

(click to enlarge)

Time delays are set by switch SA1. Interval - switching resistors R1 - R6. If it is necessary to obtain high accuracy, the latter must be selected quite carefully. In our case, this is not required, so an accuracy of 1%, that is, two or three decimal places, is quite sufficient. In the diagram, the resistors are shown single, but in fact each of them can consist of several resistors connected in series. In position 1 of switch SA1, the exact frequency (on the resistance diagram of resistors R1 - R6 are indicated for such a case) of the internal oscillator of the microcircuit is 13106 Hz. and the exposure time is 15 minutes; in position 2 - 6552: 3 - 4367. 4 - 3275. 5 - 2182.6 - 1637 Hz with a corresponding change in exposure time: 30. 45. 60. 90 and 120 min. When selecting resistors R1 - R6, the author used an electronic multimeter. But you can control the frequency at the output R (pin 6 of the DD1 chip) with an electronic frequency meter. Code 11100, present at the inputs of the frequency divider setting, corresponds to a division factor of 23.

Before starting work with the device, select the desired time interval with the SA1 switch. Next, briefly (1 ... 2 s) press the button SB2 "Start" and turn on the device. In this case, the mains voltage is supplied to the load, a voltage of +4 V appears at the output of the rectifier VD7 - VD9 and the HL1 LED lights up. signaling the inclusion of the timer and the beginning of the time delay. With a parametric stabilizer consisting of R12 elements. VD2. C2. voltage +5 V comes to the DDI chip. Its internal generator begins to generate pulses with a frequency determined by the elements of the frequency-setting circuit: capacitor C1 and one of the resistors R1 - R6.

After the supply voltage is applied, level 1 appears at the END output of the DD0 microcircuit. It enters through the VD1 diode to the inputs 5 and 6 of the DD2.1 inverter, at the output of which level 1 appears, which opens the transistor VT13 through the resistor R2. Its current flows through the winding of relay K1, it works by shunting its contacts K1.1 with the SB2 "Start" button. In this case, after releasing the button, the device will remain on.

The O level from the END output of the DD1 microcircuit also goes to the input (pin 13 of the DD2.2 element) for controlling the audio signal generator assembled on the DD2.2 elements. DD2.3. R8. R9, C3, which is turned off.

Level 0 at the END output of the DA1 chip will remain until then. until the set time delay expires, after which it will change to level 1. The latter will start the sound signal generator. From its output, pulses with a frequency of 1 kHz through the transistor VT1 arrive at the sound emitter HA1.

In addition, level 1 closes the diode VD1. Capacitor C4 starts charging through resistor R10. Transistor VT2 will be open for about another 10c (τ = 0,7 R10 C4).

During these 10 seconds, you can change the time delay with the SA1 "Interval" switch and (or) restart the timer with the SB1 "Repeat" button. If neither. nothing else will be done, capacitor C4 is charged to level 1. inverter DD2.1 switches, level 0 at its output closes transistor VT2. relay K1 is de-energized, the contacts to 1.1 open, disconnecting the load and the timer itself from the network.

Button SB1 "Repeat" resets the output END counter chip DD1 and can be pressed at any time delay. Therefore, this shutter speed can be changed at any time, it is only necessary after each change in the position of the switch SA1 to press the button SB1 "Repeat" so that the shutter speed corresponds to the set value.

The timer is assembled on a printed circuit board made of one-sided foil fiberglass. A possible variant of tracing conductors is shown in Fig. 2 with the arrangement of parts.

Transformer T1 must provide a voltage on capacitor C5 equal to +9 .. 12 V.

Chip K561LA7 (DD2) is replaceable by K176LA7,564LA7. Emitter HA1 - telephone capsule or dynamic head 0.25GDSH-20-50 (or another with a resistance of 50 ohms).

Resistors R1-R6 - C2-29V, the rest - MLT. Capacitors C) and C3 - KM-5, KM-6 (C 1 with TKE not worse than M750J. C2, C4. C5 -K50-16. K50-35.

Diodes KD105A (VD1, VD3) are interchangeable with KD522B. The VD4-VD7 bridge is assembled on KD105 diodes with any letter index. Instead of the KT815A (VT2) transistor, any of this series will do. Transistor KT3102 (VT1) is also any of this series or KT315A - KT315E.

In the device, you can use a relay with a trip current of 55 ... 60 mA at a voltage of 7.5.-9 V (the author used a powerful role RP20M-215-UZ, the passport is unknown). Relay contacts and buttons

SB2 must be designed for switching AC voltage 220 V and rated load current.

Establishing the device is reduced to the selection of resistors R1 - R6 so. as stated above.

Literature

1. Gorodetsky I. Dialogue automaton for switching off the load. - Radio. 1997. No. 4. p. 9.
2. Ivanov A. Infra-low frequency rectangular pulse generator based on KR512PS10. - Radio. 1991. No. 12. p. 32.33.
3. Ivanov D. "Pocket" metronome. - Radio. 1993. No. 3. p. 36.37.
4. Biryukov S. Frequency divider generator KR512LS10. - Radio. 2000. No. 7. p. 51-53.
5. Biryukov S. Application of the KR512PS10 chip. - Radio. 2000. No. 7. p. 44

Author: E.Zuev

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