Motion sensors are an incredibly handy thing that lets you control the light in the room or control the opening and closing of doors, and can also alert you to unwanted guests. In this article we will tell you how to make a motion sensor with your own hands at home and consider the scope of possible use of such devices.
Briefly about the sensors
One of the simplest types of sensors is a self-resetting (non-latching) limit switch or button.
He sits at the door and reacts to its opening and closing. Using a simple circuit, this device turns on the light in the refrigerator. It can equip a pantry or a vestibule of a corridor, a door in an entrance, LED lighting in service, use this switch as an alarm system which will warn of the opening or closing of a door. Design flaws can be installation difficulties and sometimes an unrepresentable appearance.
Based on reed switch devices and a magnet can be seen on doors and windows of protected objects. Their principle of operation is very similar to the operation of a button. A reed switch can open or connect contacts when a conventional magnet is brought to it. So the reed switch itself is installed on the door, and the magnet hangs on the door. This design looks neat and is used more often than a regular button. The lack of devices in narrowly specialized applications. They are not suitable for controlling open areas, areas, passages.
There are devices for open walkways that respond to environmental changes. These include photoelectric, capacitive (field sensors), thermal (PIR), sound relays. To fix the intersection of a certain section, control obstacles, the presence of movement of any object in the area of overlap, use photos or sound echoes.
The principle of operation of such sensors is based on the formation of a pulse and its fixing after reflection from the object. When an object enters such an area, the characteristic of the reflected signal changes and the detector generates a control signal at the output.
For clarity, a block diagram of the operation of the photo relay and the sound relay is shown:
Optical sensors use infrared LEDs as the transmitting device and phototransistors as the receiver. Sound sensors work in the ultrasonic range, so their work for our ear seems to be silent, however, each of them contains a small emitter and a trap.
Motion sensors are an incredibly handy thing that lets you control the light in the room or control the opening and closing of doors, and can also alert you to unwanted guests. In this article we will tell you how to make a motion sensor with your own hands at home and consider the scope of possible use of such devices.
Briefly about the sensors
One of the simplest types of sensors is a self-resetting (non-latching) limit switch or button.
He sits at the door and reacts to its opening and closing. Using a simple circuit, this device turns on the light in the refrigerator. It can equip a pantry or a vestibule of a corridor, a door in an entrance, LED lighting in service, use this switch as an alarm system which will warn of the opening or closing of a door. Design flaws can be installation difficulties and sometimes an unrepresentable appearance.
Based on reed switch devices and a magnet can be seen on doors and windows of protected objects. Their principle of operation is very similar to the operation of a button. A reed switch can open or connect contacts when a conventional magnet is brought to it. So the reed switch itself is installed on the door, and the magnet hangs on the door. This design looks neat and is used more often than a regular button. The lack of devices in narrowly specialized applications. They are not suitable for controlling open areas, areas, passages.
There are devices for open walkways that respond to environmental changes. These include photoelectric, capacitive (field sensors), thermal (PIR), sound relays. To fix the intersection of a certain section, control obstacles, the presence of movement of any object in the area of overlap, use photos or sound echoes.
The principle of operation of such sensors is based on the formation of a pulse and its fixing after reflection from the object. When an object enters such an area, the characteristic of the reflected signal changes and the detector generates a control signal at the output.
For clarity, a block diagram of the operation of the photo relay and the sound relay is shown:
Optical sensors use infrared LEDs as the transmitting device and phototransistors as the receiver. Sound sensors work in the ultrasonic range, so their work for our ear seems to be silent, however, each of them contains a small emitter and a trap.
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