Burglars Beware, my Infrared Sights are Set on You
Heat wave infrared sensors, or more commonly known ‘Motion Sensor’ catch anything 35 lbs and up (typically). There are motion lights that can come on when you get close to the front pouch or when criminal approaches providing you with ample lighting to get in while serving as a deterrent to criminals. There are also motion detectors that take pictures of anything within a certain range when it is triggered (like the Canary or the Piper product).
They come in all shapes, sizes and colors.
What Exactly is a Motion Sensor?
Motion sensors are gadgets that utilize different technologies to detect when a person or thing has entered into its area of reach. Put differently, a motion detector is a gadget that detects motion. A motion detector can be combined with other gadgets and appliance to further enhance its function for example, motion activated lighting that comes on when someone is detected around its perimeter thereby reducing power consumption etc. Another very common use is in home security systems, a motion detector triggers an alarm when it detects motion in its perimeter. Other uses for motion sensor abounds and more are being introduced.
When it comes to security and energy efficiency, motion sensors are common. They can be applied to security cameras or burglar alarms, turning them on when they detect nearby motion. The control panel of your security system, which is connected to your monitoring center, receives a signal from a sensor when it notices motion. This warns you and the monitoring station that your home might be under attack. When it detects no more motion, it can be an energy saver by turning off the lights in a facility, which is frequently used in offices or restrooms.
Most security systems such as ADT, Vivint or Protect America all come with 1 to 2 motion detectors per package. Most are now wireless and will sound a beeping noise before the battery dies in years to come. If it is wired, it is most likely a 2-in-1 security camera + motion sensor. These are part of the standard security system package along with a control panel (usually a 2gig or Honeywell), window and door sensors and security stickers.
How Does Motion Sensor Work?
Utilizing varied technologies, a motion sensor working within a particular range of distance would trigger its function when it detects motion within its perimeter. Once it detects a large heat wave (typically 30-45 lbs) it will trigger the alarm system and sound the siren off. If being monitored by a company you will be notified and the dispatch called.
This is how a motion sensor sees humans – as bursts of heat waves.
This brings up a common issue with motion detectors which is, dogs. If you have a pet over 30 lbs that stays in the home while you are gone (or want the alarm system set) you are better off with glass break sensors and not motion detectors. Otherwise this will result in a lot of false alarms throughout the day.
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Types of Motion Sensors
The technology by which a motion sensor works differs from one to another, this is because the various methods are available to serve as a trigger for a motion detector.
These technologies include: Passive Infrared (PIR), Microwave Occupy Sensor, and Dual technology. They are the three types of motion sensors that are most frequently used.
PIR Motion detector (most common). Image from Adafruit
PIR
Otherwise known as the passive infrared technology, this technology is sensitive to change in temperatures, it detects a slight change in body temperature through emitted black body radiation at mid-infrared wavelengths (source), it finds use in motion activated light bulb and security systems. When a moving object sets off multiple zones in an activated motion sensor area, the trigger is set off and it carries out its function of turning on the light or setting off an alarm.
Two slots on the PIR are made of a unique infrared-sensitive substance. The sensor identifies movement when it notices a differential shift between the two slots since this results in a pulse.
Microwave Occupy Sensor
Microwave technology is an active technology compared with passive infrared technology discussed above. This sensor is regarded as active sensors because it emits and utilizes energy. The microwave active sensor continually emits microwave and gets triggered when a body reflects the wave back to it. The microwave technology finds use in automatic doors. Not common with home alarm system providers. Users would have to go out of their way to use one of these.
A Dual tech occupy sensor shown by TopGreener.com
Dual Technology
A new technology in modern motion sensor, the dual technology makes use of both the passive infrared and the active microwave technologies. It works best when both systems are activated reducing false triggering but at the expense of greater vulnerability.
Other technologies in use include:
- Ultrasonic
- Tomographic sensors
- Vibration
- Gesture sensors
- Active infrared or reflective
- Photoelectric
- Security camera integration + smartphone software (shown below courtesy of Online-Sciences.com)
Features to Consider When Purchasing a Motion Sensor
The following features should be considered when purchasing a motion sensor:
- Motion detection area determined by angle and range. Outdoor motion detector has longer range than indoor motion detector whose range is limited by walls.
- Indoor motion detector lighting functions either by occupancy or vacancy or both. This means in occupancy, the light comes on when a person enters a room, the individual is expected to turn the light off when living the room, in vacancy functionality, the light goes off when it detects that the room is empty, this means the individual is supposed to turn on the switch. Newer models of motion sensor lighting’s utilize both functionalities. This means that the lighting comes on when a person enters the room and goes off if it deters that the person has left after some time. Be sure of what you need and are getting.
- Ease of installation. Will you be doing it yourself or have a professional company come and put them into corners of wall?
- Mounting positions: Motion sensor can be installed on the wall, ceiling etc. some manufacturer offer either one or both positions. Living room and hallways are most common so they cover a lot of ground. Motion sensors have a 20-40′ range and detect heat waves of 30 pounds or more. *Notice, each motion sensor can vary on these statistics based on manufacturer.
- Sensor technology: Understanding the technology a particular sensor utilizes would help in deciding of it works well for you.
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Frequently Asked Questions
What is the difference between PIR and a regular motion sensor?
A regular motion sensor only detects motion and nothing more. While it does the job well, it can sometimes get triggered by things that shouldn’t be alarming, such as falling leaves or a bigger gust of wind. PIR or Passive InfraRed motion sensors, on the other hand, use infrared beams to reliably detect people, large pets & other large warm moving objects.
As such, a PIR motion sensor won’t get triggered as easily. Instead, it will only count moving objects of different temperature as a threat. Because of the way this system works, you’ll have fewer false triggers to deal with.
How many motion sensors do I need?
You don’t need countless motion sensors for your home’s security system to be effective. In fact, having too many motion sensors can render your security system useless. Since motion sensors tend to have the capability to monitor a large amount of area, one motion sensor per room is typically effective.
How far can a security camera detect motion?
Typically, a good motion sensing camera can detect motion up to 15 feet, while also allowing you the luxury of adjusting the sensor’s sensitivity to your liking.
Should I consider putting a motion sensor in my garage?
No, it’s not a good idea to put one in your garage, at least not one that detects heat. The thing with garages, attics, patios, and sunrooms is that they tend to heat up quite well and thus they might trigger the PIR motion sensor out of the blue. If you truly feel that a burglar might use one of these rooms as an entry point inside your home, then you can try putting a motion sensor that isn’t activated by heat in any way.
Wrap up of this Motion Detector Guide
While a motion sensor finds use in a different scenario like security, lighting, doors etc. it’s important to understand how it works in order to get a system that suits your specific needs. Looking to use a motion sensor or intending to purchase a unit? Let us know your thoughts in the comment section.
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Growing up with Law and Order and CSI shows taught Isabelle Landau one thing: if people back then had high-quality home security systems, those series would have been way shorter. In our modern world, technology helps us keep burglars away easily, and this is what Izzy studies and writes about: alarm systems, home security, protection systems, and more.
Last update on 2025-11-24 at 23:37 / Affiliate links / Images from Amazon Product Advertising API
Lora says
The motion sensors available today are really awesome and some of them pack the best features and are super effective. I’ve been utilizing motion sensors at home so I would vouch that they really are worth the purchase. I think installation is fairly easy if you just follow the instructions!
Carl says
Motion censors are fantastic and a lot better than they were in the 90’s! I owned my first home in the 90’s and then lost my job. I had to relocate back closer to family and rebuild my life again. Several years later I am a home owner again and I am blown away by the technology advancements that have been made!
Vickie Holmes says
Oh I had a few motion to light sensors in the 80’s want to talk about an upgrade! I recently bought some and had no idea what I was in for. I wish I seen this guide first. I got some that are VERY powerful and I didn’t have to pay this much haha My son is going to buy them off of me and use them at his cabin.