How to make a simple motion sensor. Motion sensors for turning on street and home lights: connection diagrams and recommendations

Today, presence sensors have become very fashionable to detect movement when a person moves around the room.

When you connect such a device to lighting fixtures, you will receive an automatic system for turning on the lights. Almost anyone can assemble a presence sensor to detect a person on their own. And here the assembly diagram will be the main one. You will learn everything about the assembly process from this article.

Principle of operation

The first thing you need to know when assembling such a device yourself is the principle of its operation.
Note! Many people confuse such devices with motion sensors. But these are different models.
The operating principle of the device is based on the sensor’s response to the location of a person or large animal. The operation of the device is based on the Doppler effect - a change in wavelength and frequency. These changes are recorded by the sensor and transmitted to the device to further turn on the lighting or sound signal. Moreover, the signal arrives at the sensor regardless of whether the object moves or remains motionless. The device is equipped with an antenna and a generator. Without the presence of a reflective antenna signal, the device is in sleep mode. The operating diagram is shown below.

When the device is connected to a light source, in the event of the appearance of any object in the work area, the light is activated. At the same time, to turn on the lighting as such, there is no need for movement (even a slight one).

Where is it used?

Presence sensors are actively used today in the following areas:

• “smart home” system for turning on the lights automatically (the connection diagram is shown below). In this situation, it allows you to save electricity consumption significantly;

Connection diagram

• security systems;
• robotics;
• various production lines;
• video surveillance systems;
• to control electricity consumption, etc.

In addition, interactive toys equipped with similar devices are increasingly appearing. But in most cases, when the device reacts, there is no need to turn on the light. Such products can respond to temperature, ultrasound, object weight and many other parameters. The lighting does not turn on here. The device reacts, for example, by turning on the sound or transmitting a signal to a portable mobile device (for modern models).
Such developments are especially indispensable in the security system. But not every person can afford to purchase such a device. They are quite expensive and may not be affordable. Therefore, some people make such devices with their own hands.

Let's start assembling

In order to assemble the sensor, you will need the diagram below.

In addition to this you will need:

• microwave generator;
• transistor KT371 (KT368), which must be pre-amplified by KT3102;
• comparator;
• microcircuit K554CA3.

All the necessary components for assembly can be found on the radio market or in specialized electronics stores.
According to this diagram, it is necessary to assemble and solder the above elements.
According to the given diagram, the sensor will work like this:

• the generator produces a microwave signal;
• then it is transmitted to the whip antenna;
• then the signal is reflected from an object moving in the controlled area;
• the result is a frequency shift;
• then it is returned to the antenna and microwave generator.

At this stage it will operate as a direct conversion receiver. This is due to the fact that the received signal is converted into infrasonic (low frequency).
After signal conversion, the following happens:

• now the low-frequency vibrations already received, reaching the pre-amplifier, are amplified;
• they are then transmitted to the comparator and converted into pulses (rectangular).

If the signal is not reflected, then a high level voltage is obtained at the output of the comparator.
A trimmer capacitor is needed to set the frequency. It must be equal to the resonant frequency of the antenna.

Note! This parameter should be selected according to the maximum sensitivity of the sensor.

From a constructive point of view, the device must be made on a printed circuit made of fiberglass. The board must be placed on a plastic case.

Printed circuit (example)

You can use a piece of rigid wire as an antenna. For its manufacture, it is better to choose copper wire. We solder it to the contact pad of the resulting board. The antenna output is carried out through the output on the housing. Experts recommend placing the antenna vertically.
Remember that any shielding objects should not be placed in the immediate vicinity of a self-assembled sensor. In addition, you should know that for the normal functioning of a soldered product, its common wire must have a capacitive connection to the ground.

Final stage

After you have installed the compact device, it should be hung on the inside of the door, as close as possible to the door handle and door lock. The product can also be placed in other places. The main thing is that the controlled area is sufficient.
During installation, it is necessary to ensure that the length of the conductors and leads of the elements is minimal. This will avoid interference, which could result in the device not working properly.
Following the instructions and diagram provided, it is relatively easy to assemble a presence sensor with your own hands. The main thing is to mount all the components in the right order.

Choosing the right autonomous sensors for driving with a siren Review and installation of the remote control for radio control of light

Today, almost everyone knows what it is. This device has proven itself well both in office premises and in the private sector. The cost is not always affordable. In this article we will describe in detail how to make a homemade sensor for lighting with your own hands, using a simple scheme.

Basic information about the motion sensor

Let's look at some information about the motion sensor for lighting and its scope.
A motion sensor is a device whose main function is to detect movement in its coverage area. There are three types of sensors - passive, active and mixed.

The operating principle of the active sensor is based on the radiation of ultrasonic and electromagnetic waves. Passive, has an infrared sensor that detects human heat. Mixed motion sensors have both control devices.

How the device works

Active sensors, by recording and comparing data received during radiation, alert movement if there is a shift in the data.

Advantages of ultrasonic sensors:

1. Low cost.
2. Unaffected by weather conditions.
3. Recognize movement regardless of the material.

Disadvantages of ultrasonic devices:

• Range limitation
• They are designed for fairly sudden movements.
• Animals are sensitive to ultrafrequencies.

Most often, such devices are used in car security systems.

Pros of RF motion sensors:

• Their sizes are small.
• Long range models are available.
• Very accurate.

Disadvantages of radio frequency devices:

• Their cost is quite high.
• Due to the high sensitivity threshold, false motion detections occur.
• The high power of the device can have a bad effect on the human or animal body if left in the field for a long time.

They are used in security systems

Passive devices have infrared sensors that monitor the temperature within their range. When the temperature data changes, the device is triggered. This type of device is used more often for lighting in residential areas.

IR sensor device

Pros of an infrared sensor

1. They are safe for people and animals.
2. They can be easily customized.
3. They work great both indoors and outdoors.
4. The price is satisfactory.

Disadvantages of an infrared sensor

• Such a device only works within certain temperature limits.
• It does not pick up objects coated with infrared blocking material.
• The device malfunctions when exposed to heat flows from heaters and warm wind.

Everything you need for making

Required tools and elements for assembly:

• Volt-ohmmeter
• Soldering iron
• Wires
• Plumbing gasket
• Screw
• Laser pointer
• Transistors
• Photodiode FD 265
• Relay RES 55A
• Resistors
• power unit

Assembly diagram

Assembly works, work in stages

The motion sensor circuit for lighting is very simple. For those who have been involved in the repair of electrical appliances, this will not be difficult to do.

Stages of work:

1. To get started, you should prepare the power supply. The connector should be cut off. Then use a voltmeter to find the plus.
2. Then you should solder a 10 kohm resistor.
3. The photodiode cathode must be soldered to a resistor, which is soldered to the positive.
4. By soldering, we connect the photodiode anode to the construction resistor. The emitter of the transistor should be soldered to the negative of the resistor. The required collector is connected to the VT 1 base, which is soldered to R1.
5. Then the emitter of VT 2 should be connected to the minus, the relay contact should be connected to the collector of VT 2. Another relay contact should be soldered to the plus of the power supply.
6. The most common is the use of a laser pointer, and that is what we use. To save money, we also solder two additional wires to the power supply.
7. We insert the cord into the plumbing gasket, with the cap inside, you need to insert it into the pointer - so that the cap rests on the spring inside.
8. One wire from the power supply should be connected to the screw, and the other should be inserted between the gasket and the body of the pointer.

Before turning on, you should check the diagram again. If everything matches the diagram, then we check the operation of the device.

How to connect the device and adjust sensitivity

In order for the device to work properly and cope with the task, you need to take a responsible approach to its installation. The best place for installation is the doorway. For a more aesthetic appearance, the device can be placed in a plastic box by making a hole for the photodiode.

Mounts the sensor at a height of about a meter, from the floor. The pointer should be installed parallel to the floor and so that the beam hits the photodiode, then the sensitivity during operation of the device will not be impaired, and there will be no need to resort to repairing it.

After installation is complete, you can hide the wires, so they will not spoil the appearance or get tangled underfoot. It is advisable to think about installing the device during renovations in the room, then it will be easier to hide the wires connecting to the lighting. When making repairs, it is easier to think about the location of the device.

In order for the sensitivity to be good, you need to ensure that the pointer is installed correctly. If it is installed correctly, then the sensitivity will be normal, and the device will not malfunction and will not need to be repaired.

When installing, remember that if the photodiode is dirty or the pointer beam is obstructed, the operation of the device may be impaired.

Summarize

This device is widely used when installing a security system using not only light, but also sound. It was easy to connect this device to the lighting and turn on the lights automatically in the living room.

This is how a smart home system is created. Such a device is a fairly economical option. It will help you significantly reduce your energy costs.

Various connection schemes

Very often it is used in bathrooms, kitchens, hallways, and basements of private houses. In the bathroom and toilet, the device is connected not only to lighting, but also to ventilation, which makes it much easier to ventilate the room.

Without special education, anyone can make a motion sensor with their own hands for lighting. This homemade device will not take a lot of time and money to create. After all, the scheme is quite simple, and everyone can easily repeat all the manipulations.

Motion sensors for turning on street and indoor lights help to rationally use resources (energy savings of 50-80%), identifying the presence or movement of objects on the site. Modern technologies bring convenience to our lives and increase the comfort of our existence. Motion sensors automatically turn on the lights when a person enters the control zone. When the object moves, the light turns on automatically. This device is extremely convenient when you need to turn on the light, but at the moment your hands are busy with something. And if there is no movement for some time (which is set individually), the lamp goes out. How to set up a street motion sensor for lighting? How is a motion sensor connected?Where can motion sensors be used to turn on lights?

Yes, anywhere. And more specifically, where a person is not for long, that is, in corridors, on stairs, storerooms, at the entrance, at the gate.

A motion sensor is a special device that belongs to the category of detection devices. Using sensors, it detects a moving object that falls within its coverage area and transmits the received signal to the lamp.

When purchasing a sensor to turn on the light, you must take into account its parameters and features:

1. Installation location: devices for turning on lights can be installed outdoors, indoors, under canopies. They can be mounted or built-in; you also need to take into account the specifics of the mounting and the level of security of the device.
2. Features of installing the sensor depend on its power. The type of device affects the conditions for its installation.
3. It is necessary to take into account the characteristics of the response zone, since the alarms have access only to visible areas for monitoring. The response radius is reduced even due to hanging chandeliers or cornices.
4. Glass is a barrier to infrared rays.
5. You should pay attention to the presence of a function for setting the exact time when the light is turned on or off. This aspect will be important if the rooms are large, where there is not one sensor, but several devices.
6. It is important to consider the viewing angles of the device; the perception radius of these devices varies from 180 to 360 degrees. Sensors with 180-degree perception are often installed on walls; they are triggered when an object enters or exits the room. Ceiling motion sensors are installed only with a full viewing angle.
7. It is necessary to take into account the interaction of the ranges of active and passive areas - this is relevant for an office space or a break room.
8. There are categories of devices that have the function of adjusting to human breathing.

Motion sensors: types and classification

Light sensors are divided into two types: according to the class of the alarm and the location where the installation will be made. Devices are divided into external (used for outdoors) and internal (for indoors).

The functions of street devices for turning on lights work on the principle of calculating the distance from the device to the object. Perimeter-type sensors are designed for a certain part of the territory. Their use is relevant for large private properties and extensive home areas. Most devices have a fairly wide response range: from 100 to 500 meters. You also need to take into account that certain types of specialized devices must correspond to a specific spotlight. You can install an indoor sensor in any room of the house; its main difference from its outdoor counterpart is its intolerance to temperature changes.

These devices are divided into:

1. Ultrasonic - their work is based on the reflection of ultrasound from surrounding objects. This is the most affordable, uncomplicated, durable category of sensors;
2. Microwaves work on the principle of a locator. The radar is tuned to a certain range of signals. It catches them and sends them to the alarm. Once the signal is received, the light automatically turns on. Among experts, it is generally accepted that this principle of operation is more practical than that of ultrasonic sensors. However, the cost of such devices is higher;
3. Infrared - their operating principle is similar to the reaction of an ultra-sensitive thermometer. Such sensors respond to the temperature of an object falling within their coverage area (for example, 36.6°C). It should be taken into account that these devices are dependent on changes in ambient temperature, so it is not recommended to install them in the kitchen area or entrance doors. These devices are optimally suited for residential premises; the temperature response range can be adjusted so that they are not triggered by the movement of pets.

How to connect a motion sensor

To connect these devices, you do not need any special skills; it is enough to understand the principle of connecting the wiring and the alarm device. For a more attractive aesthetic perception, the entire system is hidden in a special distribution housing. Each device is supplied with appropriate installation instructions, as well as a diagram for connecting the motion sensor for lighting.

The principle of operation is somewhat reminiscent of the process of connecting contacts in a conventional switch, since their operating parameters are identical. Here and there, a relay acts as an actuator.

It is a widespread practice to use a switch with a motion sensor, this is especially true for residents of private houses. When approaching the gate in the dark, a light above the entrance turns on, and the sensor is adjusted in such a way that a person can easily cover the distance from the gate to the house.

In cases where it is necessary for the lamp to work even when there is no movement in the room, a switch connected in parallel to the sensor is added to the circuit. Thus, when the switch is turned on, the light source will be connected to another circuit, bypassing the sensor. At the same time, the device will continue to control the lighting even when the switch is turned off.

Circuit diagram with switch connection

In some cases, when the room area is large, one sensor is not enough; a lighting source connection diagram with two devices is used. To avoid a phase-to-phase short circuit, you need to understand that both alarms are connected from the same phase.

Connection diagram for a lamp with two sensors

Owners of private houses with large local areas often combine the connection of sensors and several powerful spotlights. Since the sensor power is approximately 500-700 W, in such cases a magnetic starter is used.

Connection diagram for a motion sensor with a magnetic starter

How to set up a motion sensor to turn on the light yourself

Potentiometers are responsible for setting the sensors. They are divided into three categories:

• time intervals;
• sensitivity level;
• illumination.

Setting time intervals is the simplest. You just need to set the required time period. Depending on the device model, this value varies from 5 seconds to 10 minutes.

The higher the sensitivity level, the better the device responds to movement. If the sensor is triggered too frequently, the sensitivity threshold should be reduced. This factor also applies to spontaneous inclusions. When adjusting the sensitivity level, you also need to take into account the time of year, for example, in summer, devices operate in standard mode, and in winter, failures are common. This situation arises due to the response of devices to the heat produced by heating devices.

The light factor is important: the sensor must function correctly when it is light. Thus, when an object moves, the device should automatically determine the level of illumination. If the level is below the set threshold, the device is triggered. But if it’s higher, then no, since the room does not need additional lighting; it’s day outside.

conclusions

Motion sensors for turning on street and home lights are compact, energy-efficient, and easy to install. They are convenient and relevant for use in private homes, dachas, and surrounding areas. In addition to their direct purpose, they serve as a kind of alarm system against intruders; they are triggered precisely when strangers appear on your territory.

A motion sensor is a necessary attribute of a modern interior, the functional comfort of your home.

What are pyromodules? How to enable and use them correctly? This article will answer all these questions.

The creation and installation of pyromodules in this article will be discussed using the example of modernizing the EK-0.3 coffee maker.

As you know, this type of coffee maker does not have the function of turning off after making coffee. Very often such devices suffer a sad fate, because they can explode because they lack automation. Therefore, in order for the operation of the device to be safe and its “life” to be long, it is necessary to take certain measures.

One option is to use a special thermal switch that will turn off the coffee maker. The disadvantage of this method is that the switch will only operate when the case temperature is above 120 degrees. And at this temperature, there is usually no water in the coffee maker’s reservoir completely. As a result, all this will lead to the body of the coffee maker overheating, and the amount of energy required will increase several times. The best option is to use a motion sensor; it will independently track the moment coffee is poured into the coffee pot.

PIR (motion) Sensor (pyromodule) - what is it?

This abbreviation stands for as follows:

– PIR– Passive Infra-Red;

– FEAST– Passive Infrared.

So what is it? This device converts infrared radiation (more precisely, a change in its intensity) into electric current. In certain crystalline rock materials, if the temperature is changed, a pyrostatic effect occurs. It is on this effect that the operation of the pyromodule is based. The temperature in materials changes precisely due to infrared radiation.

The electric field needs to be registered, but to do this it needs to change. And when changing, the crystalline dielectrics will be compensated by free electric charges. All sensors built using pyroelectrics have this property. This means that they will all be able to track even the slightest change in radiation intensity. In this case, the pyromodule itself (its temperature) will not have any effect on the measurement results.

To protect the pyro-sensor from various negative influences and various interferences, it is necessary to enclose it in a sealed metal case. The housing must have a window that allows light to pass through (narrow radiation range). In order for light to pass through in this range, the window must be covered with an infrared cut-off filter. The spectral characteristic of the filter is 10 µm (1*104 nm).

Design of an imported pyromodule:

– in addition to the pyro-sensor itself, a special amplifier is also located behind the infrared filter. It operates on a unipolar low-noise transistor. The diagram above shows how to turn on the “PIR D203S” pyromodule (foreign production), as well as its pinout.

In order to connect Soviet pyromodules, you will need to install a field-effect transistor. The diagram above shows how to turn on “PM-4” (Soviet production), as well as its pinout.

Previously, pyromodules were secretly developed in military-industrial complexes. They were installed in missiles and other similar devices, and were part of Thermal Homing Heads or TGS.

Today, the use of modules in civil engineering is widespread. The most common area is motion detectors in alarm systems and lighting control systems. The picture above shows an example, a Feron LX20/SEN5 sensor, which is intended for a lighting control system.

What results should be achieved when improving a coffee maker?

• The coffee maker should turn off the power as soon as coffee starts flowing into the pot. The process will be completed without electricity; the thermal energy accumulated by the housing will be sufficient to complete it.
• The coffee maker should switch off abnormally when the temperature exceeds 120 degrees. Otherwise, it will burn out due to lack of water.

This figure shows a block diagram. The motion sensor sends signals to the control unit. The control unit, in turn, can turn off the electromagnetic relay at the right time. And thanks to an electromagnetic relay, the entire coffee maker turns off at the right moment.

This diagram shows the control unit in its electrical version. Elements of the circuit and their purpose:

• PM-4– this is a pyromodule without a built-in amplifier;
• VT1– with its help, the pyromodule signal is amplified;
• DA1-1-DA1-2– adjusts the amplification of the pyromodule signal;
• VD1– a temperature sensor based on a germanium diode;
• DA1-3– amplifies the signal from the temperature sensor;
• DA1-4– stabilizes the virtual earth;
• VS1– blocks relay P1 and its power supply. Is a threshold element;
• VT2– this relay performs a delay at certain moments. For example, it prevents the coffee maker from switching off during transition processes while power is already supplied;
• Z1– stabilizes the voltage at 12 Volts;
• Z2– stabilizes the voltage at 8 Volts.

Construction and its details.

The picture shows a printed circuit board on which all the parts are assembled, with the exception of the temperature sensor. Board dimensions – 45x85mm.

Here is the board directly assembled.

As already mentioned, the temperature sensor is made using a germanium diode. The sensor mount is made of tin can.

The sensor is attached to the body of the coffee maker; silicone sealant is suitable for more reliable fastening. You can also apply a drop of KPT-8 thermal paste between the case and the bracket. The MGTF wire is used to connect the sensor (fluoroplastic insulation).

You need to drill two holes in the coffee maker stand.

These holes are needed to carry five wires. Two wires are needed for power, one wire will control the load and two more from the temperature sensor. The control unit is made in such a way that it is suitable for repair at any time.

The pyromodule eye must be protected. A polypropylene plate is perfect for this purpose. Such a plate can be taken in a disposable syringe, cut off from the piston. The pyromodule operates in a rather narrow spectrum of infrared radiation. This spectrum can be blocked by simple glass, but polypropylene will transmit it.

Additional materials.

Repair of transformers with welded cores. A simple scheme for controlling radio and electrical devices via Com ports

Motion sensors are actively used in various areas: security systems and alarms, in systems that control access to premises, in lighting control (this is especially true when a public lighting item appears, for example, the lights in the entrance are turned on only when residents enter, in the “smart home” system - as part of integrated control lighting, ventilation, air conditioning and heating.Using a motion sensor, you can adjust climate indicators depending on the presence or absence of people in the room.

Depending on the type of radiation used, motion sensors are infrared, microwave, ultrasonic and combined.

Block diagram of any DD:

B.L.- DD, S- lighting control contact, N- “zero” wire of the lighting network, L- "phase", A- terminal for connecting lighting devices.

Connecting a motion sensor. It is enough to apply supply voltage to the terminal block terminals L And N. And we connect the load or light bulb to the contact N And A.

Adjustment knobs are usually located on the DD body. Usually there are from two to four. The type of adjustment is labeled next to the knobs.

LUX- To adjust the light level. Time- Time to turn on the timer. SENS- DD sensitivity adjustment. MIC- not present on all models - acoustic response level.

For a better understanding, I will give an elementary diagram of connecting a lamp through a classic DD.

In addition, there is a DD circuit with a standard electrical switch, and if there is a need to connect a high-power load, you can use an electromagnetic starter or relay.

If the control zone is large enough, for example, the entrance of an apartment building, then using this circuit you can connect any number of DDs.

Video: how to connect a motion sensor

When choosing a location, it is necessary to reduce the conditions that negatively affect its operation. The diagram below shows examples of the best locations to place the most widely used infrared sensor.

As can be seen from the figure, it is necessary to avoid places with possible direct exposure to external thermal radiation: radiators, direct sunlight, etc.

Be sure to take into account the features of each type of sensor so that objects that cause false alarms cannot enter their working area and at the same time control all the space needed for it. Before installing the device, you must make sure that the surface on which the installation will be carried out is not subject to vibration.

If possible, motion sensors are

Ceiling– used for installation on ceilings, floor slabs, etc. In most cases, the ceiling device design provides a circular detection zone.
Corner and wall– have a narrower focus. Their advantage is the precise selection of the observation zone, thereby reducing the number of false alarms. Wall sensors are mounted on vertical surfaces, corner sensors are mounted at the junction of walls. For corner surveillance devices, there are two mounting options - both on the external and internal corners of the room

In some universal control devices, using special fasteners, it is possible to make both direct and corner mounting - on the internal and external corners of buildings.

If possible, DD installations are:

External- differ in ease of installation; in addition, devices of this type are maximally functional and convenient, they allow you to adjust the coverage area
Domestic– allow you to install sensors as secretly as possible. There are models that can be installed not only on walls, but also on furniture, ceilings and even electrical appliances.

Based on the method of providing power, motion sensors can be divided into: autonomous And wired

Motion sensor operating on the infrared principle

The operation of IR DD is based on recording thermal (IR) radiation coming from various objects. Any object that has its own temperature generates infrared radiation, which enters through special segmented concave mirrors and lenses onto a sensitive sensor installed inside the converter, which detects this radiation. If an object moves, the IR radiation it emits periodically hits different sensor lenses. In various converters, the number of lenses can vary from 20 to 60 pieces, and as their number increases, the sensitivity of the sensor increases. The coverage area that the DD controls depends on the surface area of ​​the existing lens system - the higher this area, the larger the control area.

Advantages of IR motion sensors:

Good adjustment of detection angle and range of moving objects
They are convenient to use outdoors, because they react exclusively to objects that have heat and move
Completely safe for people and animals, because it works in passive mode, without generating any radiation

Disadvantages of IR DD:

Possible false alarms due to the appearance of various thermal radiations, even due to flows of warm air emanating from radiators, a running air conditioner, etc.
Less accurate response when working outdoors due to precipitation, sunlight, etc.
Small temperature range within which stable operation of the converter is ensured
Will not work if the object is covered with a special material that does not transmit IR radiation

The ultrasonic sensor monitors the surrounding space using sound waves, the frequency of which was beyond the audibility range of the human ear. Since at the moment of reflection from a moving object the frequency of the signal changes in accordance with the Doppler effect, then for a given change in frequency in the received signal, the converter will work.

Inside the ultrasonic DD there is a sound wave generator that generates ultrasonic waves in the range from 20 to 60 kHz. The generated wave goes into open space and, reflected from surrounding objects, ends up back at the receiver. In fact, it is a mini radar station.

With the appearance of a moving object in the control zone, the reflected waves will receive an additional frequency component - the Doppler effect. By comparison, it is isolated and generates a trigger signal for the converter.

Ultrasonic transducers are widely used in cars - they are used in automatic parking devices, as well as in systems that monitor the car’s blind spots. Indoors they found a good niche for controlling movement on stairs, and in long corridors, etc.

Advantages of Ultrasonic Sensors

Low cost
External natural factors (wind, sun, precipitation, etc.) do not affect the accuracy of operation
Fixes the movement of the test object, regardless of what material it is made of

Disadvantages of ultrasound DD:

Fairly short effective range
May not work when moving the controlled object at low speeds
Affects animals that are able to hear sound in the ultrasonic range

The circuit of this type of converter uses the principle of wave propagation in the microwave range to operate, so the principle of operation is very similar to ultrasonic DD. The microwave generator generates high-frequency waves (usually at 5.8 GHz), which are emitted by the converter into the surrounding space. When reflected from a moving control object, the wave has a “Doppler” increase in frequency, which is recorded during processing of the received signal. After which the signal is sent to the control board and the control and alarm circuit is started.

Advantages of microwave sensors

They have the smallest dimensions compared to other types
Longer range
The microwave sensor can detect movement even behind weakly conductive and dielectric obstacles: glass, doors, thin walls
the accuracy of operation is not affected by atmospheric and natural conditions
Converters of this type are guaranteed to work when moving to control objects even at low speed
Using one converter you can create several independent control zones

Minuses:

They are very expensive
There is a possibility of false alarms caused by motion capture outside the control zone
Unsafe microwave radiation on any biological object, including humans

Combined motion sensors

A combined DD circuit is capable of combining several technologies at once, for example, a microwave sensor and an infrared one. Today, such a combination is very effective, especially when it is necessary to obtain high accuracy in determining movement in the area controlled by the device. Parallel operation of several channels greatly increases the likelihood of detecting unwanted movement; in addition, such devices complement each other, mutually compensating for the shortcomings of each type.

Video: Motion sensor device

DIY motion sensor on LM324 chip

The DD circuit can be roughly divided into three components: a signal amplifier with two comparators and a PIS209S pyroelectric sensor operating on the principles of generating electrical charges in a crystal under the influence of thermal (infrared) radiation.

The best part is that almost all of this is already on the chip. LM324

A pyroelectric sensor consists of a pyroelectric plate flanked by metal plates that resemble a capacitor. On one of the plates there is a substance that receives thermal radiation. As soon as it causes a pyroelectric effect and the voltage between the plates increases. This voltage is applied to the gate - source of a unipolar transistor built into the sensor.

Therefore, the resistance of the transistor channel decreases. VT1 loaded onto an external load resistance (not shown in the figure), from which the generated signal is removed. Resistance R1 intended for discharging the plates of the pyroelectric sensor capacitance.

Do-it-yourself motion sensor on a pyrodetector

I spotted this circuit in the book Radio Amateurs - circuits for the home, but did not repeat it.

Photo relay SFZ-1 is used to ensure that the light turns on only in the evening and at night. Otherwise, bipolar transistor VT1 is open, and its colleague VT2, operating in switch mode, enters saturation mode, thereby blocking the light from turning on.

In the dark and when a biological object appears in the DD coverage area, the infrared background changes sharply and a signal is generated, amplified by the operational amplifier and sent to the input of the time relay. By changing resistances R2 and R11, you can adjust the sensitivity of the circuit.

The signal coming from the op-amp opens transistor VT3 and charges capacitor C6. After charging it, transistor VT4 will open, which in turn switches relay K1. And the relay will turn on the lighting through its front contacts. With the values ​​​​indicated in the diagram, the delay for turning off the lighting is 70 seconds.