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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Automatic Light day for household plots. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Lighting Homestead greenhouses play a significant role in the subsidiary farming. But a green cucumber or flowers for the holiday require a lot of work and skill. One of the main parameters for growing winter greens is lighting. So, for example, for a cucumber, daylight hours should be 16 hours, and for tomatoes - 18 hours [1]. In some greenhouses around the clock lighting is practiced. However, for the normal physiological development of plants, several hours of complete darkness are required. Existing automata for greenhouses [2] allow you to program the switching on and off of additional illumination at a fixed time. For example, from 18.00 to 22.00. However, as you know, the maximum change in daylight hours occurs on days close to the equinox (autumn or spring). This is due to the fact that when the sun passes through the celestial equator, it has a maximum angular velocity. And vice versa. The minimum change in daylight hours occurs on days close to the solstice. The name itself speaks of the stopped sun. The sun is at the highest (lowest) point of its orbit (the ecliptic) and has a minimum angular displacement. This small digression into the course of school astronomy allows us to better understand why the day decreases in autumn and increases in spring. Therefore, the main disadvantage of the existing automatic machines for greenhouses is the fixed time of turning on and off the illumination of additional lighting. Proposed day light machine turns on the lighting at dusk and turns it off when the programmed daylight hours have elapsed. Daylight hours are set from 12 o'clock to 15 o'clock in one hour using two switches. The advantages of the proposed machine include the fact that the installation of a photoresistor is not critical to the direct light from the greenhouse lighting. The uncertainty of the transient process at the moment the meter is turned on has also been eliminated. It is possible to turn on (off) the lighting in manual mode. This machine can be used when switching on the lighting for the aquarium and in other cases where it is necessary to extend the daylight hours, for example, in a poultry house or in a livestock building. Schematic diagram of the machine:
The machine consists of a master oscillator and a pulse divider on a DD1 chip. Divider for 60 DD4 and reversible counter with pre-installation DD6; pulse shaper on the elements DD2.1, DD2.2; control unit on chips DD5, DD2.3, DD2.4, DD3.1, DD3.2, DD3.3. Two long-duration pulse shapers, consisting of differentiating chains C6, R7 and C5, R6; and inverters on the elements DD3.4, DD7.2 and DD7.1, DD7.4. Keys on transistors VT1, VT2 and relays K1, K2. The operation of the machine is based on programming the daylight hours by setting the code on the reversible counter DD6, followed by subtraction with a resolution of one hour. The counters are started in the morning, after the illumination of the photoresistor. After turning on the supply voltage, pin 9 of the DD2.3 element will be a logical zero, and pin 10 will be a logical one. The logic unit level from pin 10 resets the trigger DD5, and pre-installs the counter DD6. The crystal oscillator and divider on the DD1 chip, built according to a typical switching circuit, start working immediately after the voltage is applied. From the output 10 DD1 pulses with a period of 1 minute are fed to the input 7 of the divider by 60 DD4. However, the counter does not count, since the zeroing input (pin 9 DD4) and the transfer input (pin 5 DD6) are supplied with a prohibitive logic one level from pin 2 of the DD5.1 trigger. In the dark, the photoresistor R3 has a high resistance with respect to the resistor R2, therefore, at pins 1, 2 of the DD2.1 chip, there is a logical one level, and at the counting inputs 3,11 of the DD5 trigger, there is a logical zero level. In the morning, when the lighting increases, the resistance of the photoresistor R3 decreases and the voltage at the terminals 1,2 DD2.1 begins to approach the level of logical zero. The moment of uncertainty between the level of one and zero is smoothed out by a large capacitor C3, which is slowly recharged. The zero level from pin 4 DD2.2 is fed to the inputs 12 element DD2.4 and 1 element DD3.1. But if element DD2.4 is opened by one from pin 2 of DD5.1, then element DD3.1, on the contrary, is closed by zero from pin 10 of inverter DD3.3 (presetting the fourth bit of counter DD6 to one). Thus, the trigger DD5.1 overturns, allowing the passage of counting pulses through the counters DD4, DD6 and prohibiting the passage of pulses through the element DD2.4. A further change in the illumination of the photosensor does not affect the operation of the machine until the number of subtracted pulses from the counter DD6 reaches a level change in its fourth digit. This will happen not earlier than in five hours, or even more (up to 8 hours), depending on the levels applied to the points XT3, XT4. This achieves good protection of the channel for turning on (off) lighting in the daytime. In the evening, when daylight decreases, the resistance of the photoresistor R3 increases, and a logic zero level will appear at pin 3 of the DD3.1 element. At the counting input 11 of the trigger DD5.2, one will appear, the trigger will tip over and close the element DD3.2 for the passage of pulses. Therefore, a further change in the illumination of the photosensor does not affect the operation of the machine until the set time has elapsed. After flipping the trigger at pin 13 DD5.2, a logical unit level will appear, which is fed to a long-duration pulse shaper, consisting of a differentiating circuit on C6, R7 and two inverters on elements DD3.4, DD7.2. From the output of the shaper, a pulse with a duration of 0,5 seconds opens the key on the transistor VT2. The start relay K2 (Fig. 4) is activated for a short time, closing contacts 2,3 K1.1 and supplying power to the starter K3. The starter self-locks with contact K3.1 and closes contacts K3.2 - K3.4. Depending on the position of the SA1-SA3 switches, one or another lighting line EL1-EL3 is switched on. After the set number of pulses on the counter DD6 is subtracted, the transfer output P (pin 7) will be set to a logical zero. At the installation input S (1) of the counter DD6 and the reset inputs R (4,10) of the triggers DD5, a unit will be fed through the inverter DD2.3. The counter will be preset and the triggers will be reset. The differentiating chain C5, R6 and inverters DD7.1, DD7.4 will generate a stop pulse, the relay K1 will operate and open contacts 1,2 K1.1. Starter K3 will be de-energized, contacts K3.1 - K3.4 will open and the lighting will go out. This will happen at night, and in the morning the cycle of the machine will repeat again. The timing diagram of the operation of the machine at key points is given in fig. 5. Here the moment of time t1 is the moment of turning on the machine in the morning, t2 is the moment of turning on the lighting in the evening, t3 is the moment of the end of counting and turning off the machine at night. When carrying out work in the greenhouse, sometimes it becomes necessary to extend the lighting, which is easy to do with the "start" SB4 and "stop" SB5 buttons. But in this case, after turning off the lighting, do not forget to briefly press the "reset" button SB1 to reset the machine to its original state. For the same purpose, after mounting the machine, at night or early in the morning, it is also necessary to press the "reset" button SB1. In low light during the day, the light can be turned on manually, but before leaving the greenhouse, if there is still enough light, the light must be turned off. Otherwise, it is necessary to briefly shade the photoresistor to trigger automatic light off. As a backup power, a krone-type battery connected through a VD2 diode is used. With a current consumption in the counting mode of about 0,5 milliamps (in the relay operation mode - 20 mA), the backup battery is enough for the whole season. The photoresistor is best placed in a dark corner of the greenhouse, taking care that it does not get light from the moon and car headlights at night. It is also desirable to cover it with a rare mesh from insects and flies. Establishing the device begins with checking the operability of the generator and dividers on the DD1 chip. This can be done even by a tester by checking for second pulses at pin 4 and minute pulses at pin 10 of the DD1 chip. Next, a signal is observed at pin 4 of DD2.2, the photoresistor R3 is shaded and the resistance of the resistor R2 is set so that a logic unit level is set at pin 4. The resistance of the resistor R2 depends on the level of the selected illumination, at which the machine should operate, and on the resistance of the illuminated photoresistor used. Open the jumper XT1-XT2 and connect the contact XT2 to pin 4 DD1. If you have a frequency meter with a start-stop input, connect it to pin 9 DD4, and the counting input to pin XT2. Turn on the table lamp and close the photo sensor. After the end of the count, the frequency meter should display a number equal to that set at the setting inputs of the DD6 counter, expressed in minutes. If you do not have a start-stop input, connect the counting input of the frequency meter to pin 10 DD4, but then the resulting number will be expressed in hours. If there is no frequency meter, then at the moment the table lamp is turned on, note the time to the nearest minute and the number of minute pulses fed to the counter DD6 must be equal to the number set in binary code at the installation inputs. To reliably determine the moment the meter stops (by eye), connect a red LED to the contacts of relay K1 through a 1kΩ resistor. After finishing the device performance check, do not forget to restore the XT1-XT2 jumper. Switches SB3, SB4 are connected to the contacts XT3, XT4 with a fixation of the P2K type so that when the switch is pressed, a high level is applied to the contacts, and a low level is applied when the switch is pressed. These switches set the overtime in increments of one hour. Preliminary installation of counter DD6 is made for 12 hours. When the SB3 button is pressed, 1 hour is added to the preset, and when the SB4 button is pressed, 2 hours are added. Thus, the maximum daylight hours is 15 hours. If the time was set using the SB2, SB3 buttons during the day, then the new value of "light day" will be only the next day. It must be remembered that when the 561IE11 counter is operating in reverse mode, the transfer pulse at pin 7 appears at the moment the counter state passes through zero. All resistors in the MLT-0,125 device, KD522B diodes can be replaced with any pulse or rectifier ones. Capacitors C3, C5, C6 type KM6 can be replaced by electrolytic capacitors, placing a plus to the trigger terminals DD5.2 and to the photoresistor. Capacitor C4 type K53-1 can be replaced with any electrolyte. KT315B transistors can be replaced with any low-frequency silicon ones with a suitable emitter-collector voltage and power. Counter DD6 K561IE11 can be replaced by K561IE14, but pin 9 must be connected to a high level for counting in binary mode. Chips DD2, DD3, DD7 K561LA7 and DD5 K561TM2 can be replaced with similar series 176. Relays K1, K2 type RES49 passport RS4.569.426 are not intended for switching alternating voltage and current and are selected by the author from those available. Long-term operation of these relays in similar modes has shown their stable operation. If possible, the best replacement would be a relay type RES32 passport RF4.500.341. Can be replaced with a relay type RES15 passport RS4.591.003. The photoresistor R3 was used by the author from an OEP14 optocoupler with the bulb removed and the light-sensitive layer filled with epoxy to reduce atmospheric influence. The OEP14 optocoupler contains two photoresistors (pins 2,6 and 3,5), it is better to connect them in parallel. You can use any photoresistor with adjustment (as mentioned above) of the resistance of the resistor R2. Quartz ZQ1 type PK71 can be replaced with any taken from a faulty quartz watch, and if its frequency is two times lower, then instead of pin 4 DD1, you need to take pin 6. Relays are attached to the board with two copper wires through foam rubber, and quartz is installed through a rubber gasket. It is better to install the board in a shielded case. The connecting wire to the photoresistor with a length of 1 meter must be shielded. Literature
Publication: cxem.net
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