Motion sensors are made in the form of a special electronic a device that responds to movements (displacements) in its coverage area and when a moving object appears in this control sector, it generates a signal in the form of switching relay contacts.
There are many different types of these motion sensors. All of them are divided according to the principle of action. The most common microwave, infrared, ultrasonic sensors. Each type of detector has its advantages as it has its drawbacks. Compare microwave sensors with infrared sensors. Due to physical reasons, the infrared sensor often gives false positives due to the influence of heat fluxes of heating and air conditioning systems, and also for the same reason unsteadily carries out monitoring on the street.
Compared to IR, a microwave sensor can have a much larger monitoring and detection zone and can respond to movement behind light walls, doors, etc. The fluctuation in room temperature does not affect the operation of the device. This sensor can be triggered by a small movement of a person. The microwave sensor can be located covertly - behind a suspended ceiling, behind a window pane, behind a small partition, etc.
This RCWL-0516 sensor generates high frequency radio waves. All the functionality of the radio wave sensor is based on the Doppler effect. When a moving object appears in the coverage area, the wave frequency reflected from it changes, which leads to a transition to an alarming mode of operation.
The RCWL-0516 sensor itself is a printed circuit board measuring 17.3 x 35.9 mm. Its supply voltage is 4-28V, with a consumption current of 3mA. Its price on Aliexpress is 30-40 rubles.
Based on this radio wave sensor RCWL-0516, you can automatically control the light of the outdoor area. The weather will not affect at all because the device will be installed indoors or behind the window glass in the house.
Enumeration of tools and materials.
- sensor RCWL-0516 -1pcs;
- DC relay 12 V -1pcs;
- connecting wires;
- power switch -1pcs;
- transistor KT815,817-1pcs;
- circuit board ;
- Light-emitting diode ;
- rectifier diode;
- tuning resistor 500-1000 kOhm;
- resistor 1 kOhm-2 pcs;
- terminal blocks;
- distribution box;
- screws;
- power supply for 12 V;
soldering iron;
- tester.
Step one. Wiring the circuit on the circuit board.
Since the RCWL-0516 sensor board itself does not provide enough voltage at the OUT output for direct connection of the relay, that is, there is a need to add a key on the KT815 transistor. In parallel with the relay coil, solder an LED to indicate operation and any rectifier diode to suppress pulses.
The voltage of the relay coil will depend on the magnitude of the supply voltage of the circuit itself. That is, if you need to power a circuit with a voltage of 5 V and set the relay to 5V. If the supply voltage of the circuit is -24 V, then we select the relay with a coil voltage of 24V.
There are contacts on the board for installing an additional capacitor -C-TM (for changing the relay exposure time - its capacity can be calculated as T = (1 / F) * 32678)
You can assemble this circuit both on the circuit board and make your own printed circuit board for this (depending on your desires and needs).
Second step. Setting up and checking the work.
The RCWL-0516 microwave sensor has an object detection distance of about 5 m. In my case, this did not suit me — I had to have a range of three meters. Yes, and I wanted to be able to adjust the limits of the sensor operating zone. To do this, solder the constant resistor R9. In its place we solder a tuning resistor from 500 to 1000 Ohms. Now, with this variable resistor, you can smoothly adjust the object detection distance from 0.1 to 5 m.
Step three. Final assembly of the device.
We connect a 220 V lamp to the relay contact and adjust the device to the desired distance for switching on the alarm mode.
Since this radio wave sensor does not need direct line of sight, it can be placed in any suitable housing. I used a plastic wiring box for this. The use of an executive relay makes it possible to control the load in the form of lighting lamps or any other executive circuits.
The manufacture of this sensor took several hours of finalization-minimal, locksmith work on the manufacture of the housing homemade Hardly ever. But we have a home-made budget, but fully functional motion sensor.
Mounted this design for protection cottages- Put the sensor itself indoors behind the window pane. As a result, the sensor monitors the street three-meter zone in front of the window.
It is possible to use the RCWL-0516 radio wave sensor even in burglar alarms, as well as schemes for switching on lighting, ventilation, automatic door opening and in a smart home complex.
The process of checking and configuring the device is posted in the video