IR SENSOR
I. What is IR SENSOR?
- An infrared (IR) sensor is an electronic device that measures and detects infrared radiation
in its surrounding environment.
- IR is invisible to the human eye, as its wavelength is longer than that of visible light (though
it is still on the same electromagnetic spectrum). Anything that emits heat (everything that has
a temperature above around five degrees Kelvin) gives off infrared radiation.
Classification of sensors :
- Active Infrared Sensors (AIR): Sensors include light emitting diode (LED) and
receiver sensor. It both transmits the infrared signal and receives the signal. When an
object gets close to the sensor, infrared light from the LED will be reflected back
from the object. The receiver detects and transmits an object detected signal. Infrared
sensors act as proximity sensors and they are often used in obstacle detection systems
(like in robots).
- Passive Infrared Sensors (PIR): Passive infrared means only receiving infrared rays
emitted from other objects such as humans, animals or any other heat source, but not
emitting any infrared rays by itself. After detecting the source of heat, the sensor will
analyze to confirm the alarm condition. So they call it passive, which only detects,
not the source of the infrared light.
Two strips of thermoelectric materials (one thermoelectric sensor).
An infrared filter (blocks all other light wavelengths).
A fresnel lens (which collects light from multiple angles into one point).
Protective cover (to protect the sensor from environmental impacts such as moisture, dust)
II. Operation Principle of Infrared Sensors:
- The operating principle of the infrared sensor is also quite simple. When an animal or human
walks past the device, a signal will appear, which will be picked up by the sensor and fed into
the processing circuit to create control or alarm effects.
- Everyone's body temperature is 37 degrees Celsius, which is the source of heat that everyone has
and if we use a body temperature sensor, we will have sensors that detect people..
- Infrared sensors will operate by using a specific light sensor to detect the wavelength of light
selected in the infrared (IR) spectrum. By using LEDs that produce light of the same wavelength
as the sensor you're looking for, you can see the intensity of the light being received. When an
object is near the sensor, light from the LED bounces off the object and enters the light sensor.
This results in a huge jump in intensity, which we already know can be detected using a threshold.
III. What do we need?
Diagram:
1. IR LED
2. Photodiode
3. LM-358M (Op-Amp)
4. 2 x 150 Ω Resistance
5. 1 x 10 kΩ Resistance
6. 1 x 10 kΩ Variable Resistance (Potentiometer/Preset)
7. 5 Volt power source
8. Wires
9. General purpose PCB or bread board (Picture Below)
IR LED:
An IR LED is a type of LED which emits light in the frequency range of Infra-Red,
hence the name ‘IR’ LED. Please note that Infra-Red radiation is invisible to the
human eye, and hence we cannot see an IR LED emit it when it actually is. But there
is a way to see IR radiations, if you want to. If you look at IR radiation through the
lens of a camera, you will be able to see it. Apart from this, in every other sense an
IR LED works exactly like an ordinary LED (Look at the picture above), consumes a
current of about 20mA and operates on around 3V DC. please refer to the diagram
given below for details on connections of the IR LED, as well as the ordinary LED, if
you choose to use one.
Photodiode:
A photodiode is a type of diode which detects light. We can think of it as having a
very high resistance when no light is falling on it. As we increase the intensity of light
incident on it, the current through it gradually increases too. So, by increasing the
incident light on a photodiode, we convert it into a normal low value resistor, which
conducts current. We should note here that a photodiode looks exactly like an LED,
sometimes, with a dark blue or black film on the outer casing (Please look at the
picture below), but we make use of it in reverse bias, that means opposite in
configuration as in the case of an LED. You can refer to the diagram above for the
connections of the photodiode, but remember to connect it in reverse bias as shown
in the circuit diagram given in the “How does it work?” section below.
IC Op-Amp LM358M (as a voltage comparator)
LM358M is a general purpose Dual Operational Amplifier (Op-Amp). Knowing the
working of an Op-amp here is really of no use to us, as we are not using it as an
amplifier as such, so we will only be talking about how we use it here in the IR sensor
circuit, what it does, but not much about how it does it. So basically, we use it to
compare two voltages, one is fixed and the other varies with an environmental
parameter. If the parameter controlled voltage is higher than the fixed the voltage,
then the IC should give one output, and if it is lower than the fixed voltage, then it
should give another output. So, we see that the IC gives only two types of outputs,
which we design to be 5 Volts and 0 Volts. This makes our sensor digital.
Now, we know how to use our Op-Amp, so let’s talk about how to connect
components to it. This IC is an 8 pin IC. Check the illustration above for the pin
layout. Output (pin 1) is where we get the 5/0 Volts, Threshold (pin 2) is the fixed
voltage, Input (pin 3) is where we supply our environment controlled voltage, and pin
4 & 8 are used to power up the IC. The best part about this IC is that it is a Dual Op-
Amp, so you can make two completely separate IR sensors using the same IC! All
you need to do is mirror all the connections on the lower three terminals of the other
half of the IC (Refer to the pin diagram of the IC).
NOTE: The way we are using this IC here and the pin configuration I have shown
here is not how an Op-Amp is used traditionally, we are actually manipulating the IC
to work as a voltage comparator.
Variable resistance:
A variable resistor is a 3 pin device which is used to vary resistance. In this circuit,
we use it to calibrate the IR sensor according to the environment. We give Vcc and
GND to the terminals which are close together and connect the center terminal to the
threshold of the IC (Assuming you are using the small triangular PCB mountable
package like the one shown below).
1. Adapter 5v 1a
- It is a power converter from 220V AC to 5V DC, often used to supply power, test products: mini
drill, led, small motor. Humidifier humidifier, printer, security equipment, Motor, circuit
board, .VV power supply for video bell ... with the ability to supply maximum output current up
to 1A. for Aiphone doorbell screen and technology devices.
- SPECIFICATIONS DC power supply 5V 1A
Manufacturer: Dlink
Model: AMS1-0501000FC
Input: AC 100-240V
Wide voltage input, in line with global standards.
Output power: DC 5V 1A (5v1000ma)
Cost effective, stable and reliable
Electrode polarization: Outside (-), Center (+)
DC plug size: 5.5mm * 2.1mm
2. Module replay Xp6-R
- Standby current: 1.45 mA (SLC current drawing with all used addresses; if some of the addresses
are disabled, the standby current decreases).
Alarm current: 32 mA (assuming all six relays are turned on once and all six solid LEDs ON).
Temperature range: 0 ° C to 49 ° C.
- Humidity: 10% to 85% non-conditioning.
Dimensions: height 172.72 mm x width 147.32 mm x 25.40 mm deep. - Tape measure: 0.75
mm2) to 1.5 mm2.
Maximum SLC wire resistance: 40 or 50 ohms, depends on the panel. IDC maximum wire
resistance: 40 ohms.
Relay current: 30 mA / relay pulse (pulse time 15.6 ms), pulse under panel.
Rated relay contact: 30 VDC; 70.7 VA
- Rated current:
+ 3.0 A @ 30 VDC max, resistive, no coding.
Max 2.0 A @ 30 VDC, resistive, encoder.
1.0 A @ 30 VDC max, inductive (L / R = 2 ms), encoding
0.5 A @ 30 VDC max, inductive (L / R = 5 ms), encoding
+ Max 0.9 A @ 110 VDC, resistive, no coding. 0.9 A @ 125 VAC max, resistance, no coding.
0.7 A max @ 70.7 VAC, inductive (PF = 0.35), no encryption.
+ Max 0.5 A @ 125 VAC, inductive (PF = 0.35), no encryption ..
3. Motion sensor 220VAC 10A IR 360 7m
- range of product: ARGUS presence detector
- range: ARGUS
- product or component type: Presence detector
- load type: Capacitive: 10 A, 140 µF, AC
- Incandescent lamp: 2200 W, AC Low voltage halogen lamp with wire-wound
- transformer: 500 VA
- Color tint: Polar white
- Color code: RAL 9010
- Type of packing: Carton Voltage: 220 / 230V
- Network frequency: 50/60 Hz
- Rated operational voltage: 220/230 V
- Time delay 10 s ... 30 min
- Light intensity adjustment 10 ... 1000 lux
- Horizontal detection angle 0 ... 360 °
- Detection range Radius: 7 m
4. 220V bulb
- Rated voltage is 220V
- Rated power is 75W
