Detect Window/Door opening closing using sensors

[rushi121]

How can we detect whether a home window or door is opened or closed using sensors. I know it can be done using proximity sensors and window sensors. I want to know all possible ways/sensors to detect it.

I am no way related to physics so please try to answer considering that :)

Thanks in advance.

 

[Nidum]

Micro switches and breaking wire detectors are the simplest .

 

[rushi121]

Thanks. I guess both these requires to be attached to each window/door. Is there any way we can detect without attaching anything to window/door. Something like motion sensor to figure out window is in motion, measuring pressure of room etc.

 

[Nidum]

There is a large amount of information about security detectors on the web .

Have a look here for example :

https://en.wikipedia.org/wiki/Security_alarm

 

[NascentOxygen]

How can we detect whether a home window or door is opened or closed using sensors. I know it can be done using proximity sensors and window sensors. I want to know all possible ways/sensors to detect it.

I am no way related to physics so please try to answer considering that :)

Thanks in advance.

Do you want to determine whether the window is securely locked or not? Or just differentiate between whether it is wide open for ventilation or almost closed up?

 

[Tolklein]

If you have money to spend, a 2D laser scanner could be mounted on the outside of a building, it would be able to pick up the physical opened window/door that would break the lasers path.
But standard magnetic switches on each window are the most common and cost effective

 

[mrspeedybob]

I want to know all possible ways/sensors to detect it.

There are a large number of ways to do it, limited only by the creativity and ingenuity of the engineer. (and how dissimilar 2 ways must be before you count them as 2)

Reflect light from the glass or frame, refract light through the glass, reflect sound from the glass, refract sound through the glass, measure sound penetration through the window, physical contact switch, hall effect switch, inside/outside pressure differential, inside/outside ambient noise differential, inside/outside atmospheric chemistry differential, detecting air currents coming through open window, or not coming through closed window, etc...

My cat likes to sit in front of open windows so any method that could determine the position of a cat could be used (along with a suitable cat, dog, monkey, ferret, etc...) Similarly you could put something inside the house that would attract native insects, then use some kind of insect detector (must be a hundred ways to detect insects)

You get the idea. It's almost limitless.

 

[rushi121]

Reflect light from the glass or frame, refract light through the glass, reflect sound from the glass, refract sound through the glass, measure sound penetration through the window, inside/outside pressure differential, inside/outside ambient noise differential, inside/outside atmospheric chemistry differential, detecting air currents coming through open window, or not coming through closed window, etc...

Thanks.

Do you know any existing sensors/solution in market using any of the above methods (except switches) for detection? Also, my solution should have a small form factor and it should give accurate results. Will all above suggestions do the same?

What type of engineer(s) I should look for?

 

[russ_watters]

What type of engineer(s) I should look for?

I'm not understanding the big picture here: why would you need an engineer for something that there are already dozens of commercial products for? Maybe a shopping assistant at Home Depot would be more useful...?

 

[rushi121]

I found this device on amazon. Any idea how it works?
https://www.amazon.com/dp/B00CEKMQB0/?tag=pfamazon01-20

 

[nasu]

It says there. Detects changes in air pressure.

 

[anorlunda]

The description says that it senses changes in air pressure. Perhaps as a door is opened.

 

[rushi121]

Which sensor does it use to detect air pressure?

 

[anorlunda]

I don't understand your question. Here is the text from the link you posted. What don't you understand?

Through the use of micro technology, intrusion Detection now fits in the Palm of your hand. The 2.5" tall smart sensor volumetric alarm protects your home, business, hotel, or dorm room and instantly sounds an alarm at the first sign of an Intruder. This high Tech security device constantly monitors the air pressure inside any closed space up to 1000 square feet. Should an Intruder open a door or window (or break the window) the alarm will instantly sound to scare off the Intruder and alert you to the attempted entry.
​

By the way, did you note the "up to 1000 square foot" limit? To protect a whole house you may need several of them. Probably one for each exterior room. Micro switches are simpler and less expensive.

 

[tfr000]

Simple IR motion detectors are the way to go. Wiring up all your doors and windows is a pain.

 

[sophiecentaur]

Simple IR motion detectors are the way to go. Wiring up all your doors and windows is a pain.

I agree up to a point but I have a PIR detector in our back garden. It gives many false triggers. If you don't like wires then there are wireless alarm systems which have contact switches as well as PIR units.
Changes of air pressure in a room can be caused by gusts of wind on the chimney. I wouldn't think it would be very reliable.

 

[NascentOxygen]

A room air pressure sensor. If the room pressure is aready equalised with outside pressure would gently sliding a window open cause a trigger? On a blustery day, would a gust of wind against a large window pane cause a spike in pressure of a secured room? Would the building resonance (walls & ceiling vibrate) as a plane drones overhead cause pressure changes sufficient to trigger the sensor?

Would endless false triggers see the unit being permanently turned off? Who can answer these questions ...

 

[sophiecentaur]

Who can answer these questions ...

Just a few hundred PF members?
Fools rush in . . . . . That includes me, of course. We all like an open ended question.

Security alarms are pretty common things. They tend to use a very limited number of basic components because reliability is essential. False alarms can be more trouble than failures because an intruder will often pass through more than one detector. I would suggest that the thing to go for would be what happens to be the most popular, if you want a reliable working system. (Product testing by millions of people provides good evidence.) No wires are needed for any of the readily available detectors.
If your interest is experimental then this gizmo could be worth while following up and could give you hours of fun, trying to beat it.

 

[rushi121]

Can we use passive infrared proximity sensor ( https://www.adafruit.com/products/466 ) that is used in mobile phones as window sensors? The device (that has sensor) is placed on window glass and when that device detects a window frame it will trigger alarm.

Will it work even if bright sunlight is on the window?

 

[sophiecentaur]

Will it work even if bright sunlight is on the window?

You would probably need to test it, to find out. I looked at the data sheet and it doesn't seem to be very helpful in that direction.
Contact switches and accelerometers are tried and tested ways to detect if a window is being opened or broken. Neither of them are affected by sunlight.
But it all depends whether you want a known 'result' with little effort or if you want an interesting project that could turn out to be much better than what you can buy off the shelf. More power to your elbow if you want to do some interesting experimentations!

 

[rushi121]

@sophiecentaur
How can accelerometers detect window state?

 

[sophiecentaur]

@sophiecentaur
How can accelerometers detect window state?

An accelerometer will know when it's being opened?

 

[rushi121]

Can it also detect when is it closed?

 

[sophiecentaur]

Can it also detect when is it closed?

No (of course) but, once you know its state, you can detect when it changes (even very slow changes are detectable). But, frankly, a switch contact with wireless link (if necessary) would do the best job and be easy to check and calibrate.