A simple diagram of the determinant of soil dryness with a signet. Humidity sensors - how they are arranged and work. Why is this device needed?

Automation greatly simplifies the life of the owner of the greenhouse or personal plot. An automatic irrigation system will save you from monotonous repetitive work, and an earth moisture sensor will help to avoid excess water - with my own hands such a device is not so difficult to assemble. The laws of physics come to the aid of the gardener: the moisture in the soil becomes a conductor of electrical impulses, and the more it is, the lower the resistance.

When the humidity decreases, the resistance increases, and this helps to track optimal time glaze.

The design and principle of operation of the humidity sensor

The design of the earth moisture sensor consists of two conductors, which are connected to a weak power source, the circuit must contain a resistor. When the amount of fluid in the space between the electrodes increases, the resistance decreases and the current increases.

The moisture dries up - the resistance increases, the current strength decreases.

Because the electrodes will be in a wet environment, it is recommended to turn them on through the key in order to reduce the destructive effect of corrosion. In idle time, the unit is switched off and starts only to check the humidity by pressing a button.

Soil moisture sensors in order to be able to be installed in greenhouses - they provide control over automatic irrigation, based on this, the system can function according to by and large without human intervention. In this case, the set will always be in working condition, but the condition of the electrodes will need to be monitored so that they do not deteriorate due to corrosion. Such devices can be installed on lawns and beds on outdoors- they will allow you to instantly take the necessary information.

Along with this, the totality turns out to be much more correct than a simple tactile sensation. If a person calculates the soil as completely dry, the sensor will show up to 100 units of soil moisture (when assessed in a decimal aggregate), immediately after watering this value rises to 600-700 units.

Then the sensor will allow to monitor the change in the moisture content in the soil.

If the sensor is supposed to be used outdoors, its upper part must be tightly sealed in order to prevent distortion of information. To do this, it is possible to cover it with a moisture-proof epoxy resin.

DIY humidity sensor assembly

The design of the sensor plans as follows:

• The main part is two electrodes, the diameter of which is 3-4 mm, they are attached to a base made of textolite or other material protected from corrosion.
• At one end of the electrodes, it is necessary to cut the thread, otherwise they are made pointed for more ergonomic immersion in the ground.
• Holes are drilled in the textolite plate, into which the electrodes are screwed, they must be fixed with nuts and washers.
• Under the washers, it is necessary to bring outgoing wires, after which the electrodes are isolated. The length of the electrodes, which will be immersed in the ground, is about 4-10 cm, depending on the capacity used or the open bed.
• To operate the sensor, a current source of 35 mA is required, the totality requires a voltage of 5V. Depending on the amount of liquid in the ground, the range of the returned signal will be 0-4.2 V. The loss in resistance will indicate the amount of water in the ground.
• The ground moisture sensor is connected via 3 wires to the processor, for this purpose it is possible to buy, for example, Arduino. The controller will allow you to connect the set to a buzzer to give an audible signal in case of an excessive decrease in soil moisture, or to an LED, the brightness of the lighting will change during transformations in the operation of the sensor.

Such homemade device can become part of automatic irrigation in the aggregate Smart House, for example, using the MegD-328 Ethernet controller. The web interface shows the moisture level in 10-bit aggregate: the range from 0 to 300 indicates that the soil is completely dry, 300-700 - there is enough moisture in the ground, more than 700 - the soil is wet and no watering is needed.

The design consisting of the controller, relay and battery is retracted into any suitable case, for which it is possible to adapt any plastic box.

At home, the use of a humidity sensor will be very simple and at the same time reliable.

Areas of application for the humidity sensor

The soil moisture sensor can be used in a variety of ways. Most often they are used in combinations of automatic watering and manual watering of plants:

1. They can be installed in flower pots if the plants are sensitive to the water level in the soil. When it comes to succulents, for example, cacti, you need to take in long electrodes, which will respond to the transformation of the humidity level specifically at the roots. They can also be used for other plants and violets with a fragile root system. Connecting to an LED will allow you to determine when it is time to water.
2. They are indispensable for the organization of watering plants in the greenhouse. According to a similar principle, air humidity sensors are also planned, which are necessary to start the plant spraying system. All this will automatically ensure a normal level and watering of plants with atmospheric humidity.
3. In the country, the use of sensors will allow you not to keep in mind the time of watering each bed, electrical engineering itself will tell you about the amount of water in the soil. This will allow you to prevent excessive watering, if there has been a downpour relatively recently.
4. The use of sensors is very comfortable in some second cases. For example, they will allow monitoring soil moisture in the basement and under the house near the foundation. In an apartment, it can be installed under the sink: if the pipe starts to drip, the automation will immediately tell you about it, and it will be possible to avoid subsequent repairs and flooding of the neighbors.
5. A simple sensor device will allow in just a couple of days to completely equip all problem areas of the house and garden with a warning system. If the electrodes are long enough, they can be used to control the water level, for example, in an unnatural small reservoir.

An independent manufacturer of the sensor will help equip the house with an automatic control system at minimal cost.

Factory-made components are easy to buy online or in special store, a solid part of the devices can be assembled from materials that are constantly found in the home of an electrical lover.

Do-it-yourself ground moisture sensor. Rookie AVR.

DIY soil moisture sensor. Rookie AVR.

The poet Andrei Voznesensky once said this: "laziness is the engine of progress." Perhaps it is difficult to disagree with this phrase, because most electronic devices created for the very purpose of facilitating our everyday life full of worries and all sorts of vain things.

If you are reading this article now, then you are probably very tired of the process of watering flowers. After all, flowers are gentle creatures, if you pour them a little, you are dissatisfied, you forget to water them for a day, that's all, they are about to fade. And how many flowers in the world died only because their owners went on vacation for a week, leaving the green poor fellows to wither in a dry pot! Scary to imagine.

It is to prevent such terrible situations that automatic irrigation systems were invented. A sensor is installed on the pot that measures soil moisture - it is for stainless steel metal bars stuck into the ground at a distance of a centimeter from each other.

By wire, they are connected to a circuit whose task is to open the relay only when the humidity drops below the set value and close the relay at the moment when the soil is again saturated with moisture. The relay, in turn, controls the pump, which pumps water from the reservoir directly under the root of the plant.

Sensor circuit

As you know, the electrical conductivity of dry and wet soil differs quite significantly, this fact underlies the operation of the sensor. A resistor with a nominal value of 10 kOhm and a piece of soil between the bars form a voltage divider, their midpoint is connected directly to the input of the op-amp. Voltage is supplied to the other input of the op-amp from the midpoint of the variable resistor, i.e. it can be adjusted from zero to supply voltage. With its help, the comparator switching threshold is set, in the role of which the op-amp works. As soon as the voltage at one of its inputs exceeds the voltage at the other, the output will be a logical "1", the LED will light up, the transistor will open and turn on the relay. You can use any transistor, PNP structure, suitable for current and voltage, for example, KT3107 or KT814. Operational amplifier TL072 or any similar, for example, RC4558. In parallel with the relay winding, a low-power diode, for example, 1n4148, should be placed. The supply voltage of the circuit is 12 volts.

Due to the long wires from the pot to the board itself, a situation may arise that the relay does not switch clearly, but starts clicking at the frequency of the alternating current in the network, and only after some time is set in the open position. To eliminate this bad phenomenon, an electrolytic capacitor with a capacity of 10-100 microfarads should be placed in parallel with the sensor. Archive with the board. Happy assembly! Author - Dmitry S.

Discuss the article SCHEME OF SOIL MOISTURE SENSOR

Hello everyone, today in our article we will look at how to make a soil moisture sensor with your own hands. Cause self-manufacturing sensor wear (corrosion, oxidation), or simply the inability to purchase, a long wait and the desire to make something with your own hands can serve. In my case, wear was the desire to make the sensor myself, the fact is that the sensor probe, with a constant supply of voltage, interacts with soil and moisture, as a result of which it oxidizes. For example SparkFun sensors cover it special composition(Electroless Nickel Immersion Gold) for capturing work resource. Also, in order to extend the life of the sensor, it is better to supply power to the sensor only at the time of measurements.
One "beautiful" day, I noticed that my irrigation system was moistening the soil unnecessarily, while checking the sensor, I removed the probe from the soil and this is what I saw:

Due to corrosion between the probes, additional resistance appears, as a result of which the signal becomes smaller and the arduino considers that the soil is dry. Since I am using an analog signal, I will not make a circuit with a digital output on a comparator to simplify the circuit.

The diagram shows the comparator of the soil moisture sensor, the part that converts the analog signal to digital is marked in red. The unmarked part is the part we need to convert the humidity into an analog signal, and we will use it. A little lower I gave a diagram for connecting probes to arduino.

The left part of the diagram shows how the probes are connected to the arduino, and I brought the right part (with the resistor R2) in order to show how the ADC readings change. When the probes are lowered into the ground, resistance is formed between them (in the diagram I displayed it conditionally R2), if the soil is dry, then the resistance is infinitely large, and if it is wet, then it tends to 0. Since two resistances R1 and R2 form a voltage divider, and the middle point is the output (out a0), then the output voltage depends on the value of the resistance R2. For example, if the resistance R2 \u003d 10Kom, then the voltage will be 2.5V. You can solder the resistance on the wires so as not to make additional decoupling, for stability of the readings, you can add a 0.01 uF capacitor between - supply and out. connection diagram is as follows:

Because with electrical part we figured it out, you can go to the mechanical part. For the manufacture of probes, it is better to use the material least susceptible to corrosion in order to prolong the life of the sensor. You can use "stainless steel" or galvanized metal, you can choose any shape, you can even use two pieces of wire. I chose "galvanization" for the probes, I used a small piece of getinaks as a fixing material. It is also worth considering that the insistence between the probes should be 5mm-10mm, but you should not do more. I soldered the sensor wires to the ends of the galvanization. Here's what happened in the end:

Didn't do it detailed photo report, it's that simple. And here's a photo in action:

As I pointed out earlier, it is better to use the sensor only at the time of measurement. The best option is to turn on through a transistor switch, but since my current consumption was 0.4 mA, I can turn it on directly. To supply voltage during measurements, you can connect the VCC sensor contact to the PWM pin or use the digital output to supply a high (HIGH) level at the time of measurement, and then set it low. It is also worth considering that after applying voltage to the sensor, it is necessary to wait some time for the readings to stabilize. Example via PWM:

Int sensor = A0; int power_sensor = 3;

void setup()(
// put your setup code here, to run once:
Serial.begin(9600);
analogWrite(power_sensor, 0);
}

void loop() (

delay(10000);
Serial.print("Suhost" : ");
Serial.println(analogRead(sensor));
analogWrite(power_sensor, 255);
delay(10000);
}

Thank you all for your attention!

Many gardeners and gardeners are deprived of the opportunity to take care of planted vegetables, berries, fruit trees on a daily basis due to workload or during vacation. However, the plants need regular watering. With simple automated systems, you can ensure that the soil on your site will retain the necessary and stable humidity throughout your absence. To build a garden irrigation system, you will need the main control element - a soil moisture sensor.

Humidity sensor

Humidity sensors are also sometimes referred to as moisture meters or humidity sensors. Almost all soil moisture meters on the market measure moisture in a resistive way. This is not a completely accurate method because it does not take into account the electrolytic properties of the measured object. The readings of the device can be different with the same soil moisture, but with different acidity or salt content. But gardeners-experimenters are not so interested in the absolute readings of the instruments, as relative ones, which can be configured for the actuator for water supply under certain conditions.

The essence of the resistive method is that the device measures the resistance between two conductors placed in the ground at a distance of 2-3 cm from each other. This is the usual ohmmeter, which is included in any digital or analog tester. Previously, these tools were called avometers.

There are also devices with a built-in or remote indicator for operational control over the state of the soil.

Easy to measure conductivity difference electric current before watering and after watering, using the example of a pot with an aloe houseplant. Reading before watering 101.0 kOhm.

Reading after watering after 5 minutes 12.65 kOhm.

But an ordinary tester will only show the resistance of the soil area between the electrodes, but will not be able to help in automatic watering.

The principle of operation of automation

In automatic watering systems, the rule “water or don’t water” usually applies. As a rule, no one needs to regulate the force of water pressure. This is due to the use of expensive controlled valves and other unnecessary, technologically complex devices.

Almost all humidity sensors on the market, in addition to two electrodes, have a comparator in their design. This is the simplest analog-to-digital device that converts the incoming signal into digital form. That is, at a set humidity level, you will get one or zero (0 or 5 volts) at its output. This signal will become the source for the subsequent actuator.

For automatic watering, the most rational would be to use an electromagnetic valve as an actuator. It is included in pipe breaks and can also be used in micro-drip irrigation systems. Turns on by applying 12 V.

For simple systems operating on the principle “the sensor worked - the water went”, it is enough to use the LM393 comparator. The microcircuit is a dual operational amplifier with the ability to receive a command signal at the output with an adjustable input level. The chip has an additional analog output that can be connected to a programmable controller or tester. An approximate Soviet analogue of the LM393 dual comparator is the 521CA3 microcircuit.

The figure shows a finished humidity switch together with a Chinese-made sensor for only $ 1.

Below is a reinforced version, with an output current of 10A at an alternating voltage of up to 250 V, for $ 3-4.

Irrigation automation systems

If you are interested in a full-fledged automatic irrigation system, then you need to think about purchasing a programmable controller. If the area is small, then it is enough to install 3-4 humidity sensors to different types glaze. For example, a garden needs less watering, raspberries love moisture, and melons need enough water from the soil, except during extremely dry periods.

Based on our own observations and measurements of humidity sensors, we can approximately calculate the efficiency and effectiveness of water supply in the areas. Processors allow you to make seasonal adjustments, can use the readings of humidity meters, take into account precipitation, seasons.

Some soil moisture sensors are equipped with an RJ-45 interface for connecting to a network. The processor firmware allows you to configure the system so that it will notify you of the need for watering through social networks or SMS. This is useful in cases where it is impossible to connect automated system watering, for example, for indoor plants.

For irrigation automation system, it is convenient to use controllers with analog and contact inputs that connect all sensors and transmit their readings via a single bus to a computer, tablet or mobile phone. The executive devices are controlled via the WEB-interface. The most common universal controllers are:

• MegaD-328;
• Arduino;
• hunter;
• Toro.

These are flexible devices that allow you to fine-tune the automatic watering system and entrust it with complete control over the garden.

A simple irrigation automation scheme

The simplest system irrigation automation consists of a humidity sensor and a control device. You can make a soil moisture sensor with your own hands. You will need two nails, a 10 kΩ resistor and a power supply with an output voltage of 5 V. Suitable from a mobile phone.

As a device that will issue a command for watering, you can use a microcircuit LM393. You can purchase a ready-made node or assemble it yourself, then you will need:

• resistors 10 kOhm - 2 pcs;
• resistors 1 kOhm - 2 pcs;
• resistors 2 kOhm - 3 pcs;
• variable resistor 51-100 kOhm - 1 pc;
• LEDs - 2 pcs;
• any diode, not powerful - 1 pc;
• transistor, any medium power PNP (for example, KT3107G) - 1 pc;
• capacitors 0.1 microns - 2 pcs;
• LM393 chip - 1 pc;
• relay with a threshold of 4 V;
• circuit board.

The assembly diagram is shown below.

After assembly, connect the module to the power supply and soil moisture level sensor. Connect a tester to the output of the LM393 comparator. Set the trip threshold using the trim resistor. Over time, it will need to be corrected, perhaps more than once.

The circuit diagram and pinout of the LM393 comparator is shown below.

The simplest automation is ready. It is enough to connect an actuator to the closing terminals, for example, an electromagnetic valve that turns the water supply on and off.

Irrigation automation actuators

The main actuating device for irrigation automation is an electronic valve with and without water flow control. The latter are cheaper, easier to maintain and manage.

There are many controlled cranes and other manufacturers.

If your site is experiencing problems with water supply, purchase solenoid valves with a flow sensor. This will prevent the solenoid from burning out if the water pressure drops or the water supply fails.

Disadvantages of automatic irrigation systems

The soil is heterogeneous and differs in its composition, so one moisture sensor can show different data in neighboring areas. In addition, some areas are shaded by trees and are wetter than those in sunny locations. The proximity also has a significant effect. ground water, their level relative to the horizon.

When using an automated irrigation system, the landscape of the area should be taken into account. The site can be divided into sectors. In each sector, install one or more humidity sensors and calculate their own operation algorithm for each. This will greatly complicate the system and it is unlikely that it will be possible to do without a controller, but subsequently it will almost completely save you from wasting time on ridiculous standing with a hose in your hands under the hot sun. The soil will be filled with moisture without your participation.

Building an effective automated irrigation system cannot be based only on the readings of soil moisture sensors. It is imperative to additionally use temperature and light sensors, take into account the physiological need for water of plants. different types. Seasonal changes must also be taken into account. Many irrigation automation companies offer flexible software for different regions, areas and cultivated crops.

When purchasing a system with a humidity sensor, don't fall for the silly marketing slogans: our electrodes are gold plated. Even if this is so, then you will only enrich the soil with noble metal in the process of electrolysis of the plates and wallets of not very honest businessmen.

Conclusion

This article talked about soil moisture sensors, which are the main control element of automatic watering. And also the principle of operation of the irrigation automation system was considered, which can be purchased ready-made or assembled by yourself. The simplest system consists of a humidity sensor and a control device, the do-it-yourself assembly diagram of which was also presented in this article.

LED turns on when plants need to be watered
Very low current consumption from 3V battery

Schematic diagram:

List of components:

Purpose of the device:

The circuit is designed to give a signal if the plants need watering. The LED starts flashing if the soil is in flower pot too dry, and goes out when the humidity increases. Trimmer resistor R2 allows you to adapt the sensitivity of the circuit to different types soil, flower pot sizes and types of electrodes.

Circuit development:

This little device has been a big hit with electronics enthusiasts over the years since 1999. However, as I have corresponded with many hams over the years, I have come to realize that some criticisms and suggestions need to be taken into account. The circuit has been improved by adding four resistors, two capacitors and one transistor. As a result, the device has become easier to set up and more stable in operation, and the brightness of the glow has been increased without using super-bright LEDs.
Many experiments have been carried out with various flower pots and various sensors. And although, as it is easy to imagine, flower pots and electrodes were very different from each other, the resistance between two electrodes immersed in the soil by 60 mm at a distance of about 50 mm was always in the range of 500 ... 1000 Ohms with dry soil, and 3000 ... 5000 ohms wet

Circuit operation:

Chip IC1A and its associated R1 and C1 form a square-wave generator with a frequency of 2 kHz. Through an adjustable divider R2 / R3, the pulses are fed to the input of the gate IC1B. When the resistance between the electrodes is low (i.e., if there is enough moisture in the flower pot), capacitor C2 shunts the input of IC1B to ground, and the output of IC1B is constantly present. high level voltage. Gate IC1C inverts the output of IC1B. Thus, the input of IC1D is blocked low, and the LED is accordingly turned off.
When the soil in the pot dries out, the resistance between the electrodes increases, and C2 ceases to interfere with the flow of pulses to the input of IC1B. After passing through IC1C, the 2 kHz pulses enter the blocking input of the oscillator assembled on the IC1D chip and its surrounding components. IC1D starts to generate short pulses, turning on the LED via transistor Q1. LED flashes indicate the need to water the plant.
The base of transistor Q1 is fed with rare bursts of short negative pulses with a frequency of 2 kHz, cut out from the input pulses. Consequently, the LED flashes 2000 times per second, but the human eye perceives such frequent flashes as a constant glow.

Notes:

• To prevent oxidation of the electrodes, they are powered by rectangular pulses.
• The electrodes are made from two pieces of stripped single-core wire, 1 mm in diameter and 60 mm long. You can use the wire used for wiring.
• The electrodes must be completely immersed in the ground at a distance of 30 ... 50 mm from each other. The material of the electrodes, the dimensions and the distance between them, in general, do not matter much.
• Current consumption of about 150 µA when the LED is off, and 3 mA when the LED is on for 0.1 second every 2 seconds, allows the device to work for years on a single set of batteries.
• With such a small current consumption, there is simply no need for a power switch. If, nevertheless, there is a desire to turn off the circuit, it is enough to short-circuit the electrodes.

• 2 kHz from the output of the first generator can be checked without a probe or oscilloscope. You can simply hear them if you connect the P2 electrode to the input of a low-frequency amplifier with a speaker, and if you have an ancient high-impedance earphone TON-2, then you can do without an amplifier.
• The circuit is assembled clearly according to the manual and working 100%!!! ...so if suddenly "DOES NOT work", then it's just the wrong assembly or parts. To be honest, until recently I did not believe that it was "working".
• Question for the experts!!! How can you fit a 12V constant pump with a consumption of 0.6A and a starting 1.4A as an actuating device?!
• Sobos WHERE to fit? What to manage? .... Formulate the question CLEARLY.
• In this scheme ( Full description http://www..html?di=59789) the indicator of its operation is an LED that lights up when the ground is dry. There is a great desire to automatically turn on the irrigation pump (12V constant with a consumption of 0.6A and a starting 1.4A) along with the inclusion of this LED, how to change or "finish" the circuit in order to implement this.
• ...maybe someone has any thoughts?!
• Install an opto-relay or an opto-triac instead of the LED. The dose of water can be adjusted by a timer or by the location of the sensor/irrigation point.
• It's strange, I assembled the circuit and it works fine, but only the LED "if watering is needed" fully flickers at a frequency of approximately 2 kHz, and does not burn constantly, as some forum users say. Which in turn provides savings when using batteries. It is also important that with such a low power supply, the electrodes in the ground undergo little corrosion, especially the anode. And one more thing, at a certain level of humidity, the LED starts to barely glow and this can continue for a long time, which did not allow me to use this circuit to turn on the pump. I think that in order to reliably turn on the pump, some kind of determinant of pulses of a specified frequency coming from this circuit and giving a "command" to control the load is needed. I ask SPECIALISTS to suggest a scheme for the implementation of such a device. I want to implement automatic watering in the country on the basis of this scheme.
• A very promising scheme in its "economy" that needs to be finalized and used on garden plots or for example at work, which is very important when the weekend or vacation, as well as at home for automatic watering of flowers.
• has always been within 500…1000 ohms with dry soil, and 3000…5000 ohms with wet soil - in the sense - on the contrary!!??
• I'll wash this bullshit. Over time, salts are deposited on the electrodes and the system does not work on time. A couple of years ago I did this, I only did it on two transistors according to the scheme from the MK magazine. Enough for a week, and then shifted. The pump worked and did not turn off, filling the flower. I met circuits on alternating current on the network, so I think they should be tried.
• Good day!!! As for me, any idea to create something is already good. - As for the installation of the system in the country - I would advise you to turn on the pump through a time relay (it costs a penny in many electrical equipment stores) set it to turn off after a time from turning on. Thus, when your system jams (well, anything can happen), the pump will turn off after a time that is guaranteed to be sufficient for irrigation (select it empirically). - http://tuxgraphics.org/electronics/201006/automatic-flower-watering-II.shtml Here's a good thing, I didn't build this circuit specifically, I used only an Internet connection. A little glitchy (not the fact that my handles are very straight), but everything works.
• I collected schemes for watering but not for this one which is discussed in this thread. The assembled ones work one, as mentioned above, in terms of the time the pump is turned on, the other, which is very promising in terms of the level in the sump where water is pumped directly into the sump. For plants, this is the most best option. But the essence of the question is to adapt the specified scheme. Only due to the fact that the anode in the ground is almost not destroyed as in the implementation of other schemes. So, I ask you to tell me how to track the pulse frequency in order to turn on the actuator. The problem is further aggravated by the fact that the LED can "smolder" for a barely certain time, and then only turn on in the pulsed mode.
• The answer to the question asked earlier, on finalizing the soil moisture control scheme, was received on another forum and tested for 100% performance :) If anyone is interested, write in a personal.
• Why such confidentiality and not immediately indicate a link to the forum. Here, for example, on this forum http://forum.homecitrus.ru/index.php?showtopic=8535&st=100 the problem is practically solved on the MK, but on the logic it was solved and tested by me. Only in order to understand it is necessary to read from the beginning of the "book", and not from the end. I am writing this in advance for those who read a piece of text and begin to fill up with questions. :eek:
• The link http://radiokot.ru/forum/viewtopic.php?f=1&t=63260 was not immediately given due to the fact that it would not be considered as an advertisement.
• for [B]Vell65
• http://oldoctober.com/en/automatic_watering/#5
• This is a stage already passed. The problem is solved by another scheme. As information. The lower improved circuit has errors, the resistances are burning. Printing on the same site was completed without errors. When testing the scheme, the following shortcomings were identified: 1. It turns on only once a day, when the tomatoes have already withered, and it is better to keep silent about cucumbers altogether. And just when the sun was burning, they needed [B] drip irrigation under the root, because plants evaporate in extreme heat a large number of moisture especially cucumbers. 2. There is no protection against false activation when, for example, at night the photocell is illuminated by headlights or lightning and the pump is activated when the plants are sleeping and they do not need watering, and the nightly switching on of the pump does not contribute to healthy sleep of the household.
• We remove the photo sensor, see the first version of the circuit where it is absent, we select the elements of the temporary circuit of the pulse generator as you wish. I have R1 \u003d 3.9 Mom. R8 which is 22m no. R7=5.1 Mom. Then the pump turns on when the soil is dry, for a while until the sensor gets wet. I took the device as an example of an automatic watering machine. Many thanks to the author.