Hi everyone,

I know nothing about eletronics, so i have a doubt i wish someone could answer.
I moved into a new house and i noticed a box in a corner, i opened it and it contains this circuit in the photo. Can someone say what this is? Thank you!

 

motion sensor

 

motion sensor

Thank you for your reply!!!
This is inside the house facing the entrance door, what use could it be doing?? Lights are not activated by this sensor... does this sensor have the ability to transmit info wiressly? The box were this circuit is have wires into the wall... but this circuit seems just placed inside not connected to the box...I cant understand the use for it. Any idea?Thanks!

 

Its a wireless PIR/motion sensor. It connects via a radio signal to an alarm system. The big curly spring at the top is the antenna. The other spring is a tamper switch to trigger the alarm if the case is opened. If you've just bought/moved into the house, I'd guess the alarm system is no longer there, or is no longer in use

 

Thank you for your detailed information. Well, it could be some kind of pre installed system? This kind of sensors cannot be used malliciously, right? They cannot transmit info via radio to some other persons, correct?

 

Thank you for your detailed information. Well, it could be some kind of pre installed system? This kind of sensors cannot be used malliciously, right? They cannot transmit info via radio to some other persons, correct?

Somewhere in the house is an alarm panel to which that sensor (wirelessly) connected. There are almost certainly other sensors too. It is probably the remnants of a monitored alarm service like ADT.

 

if you have alarm system, you arm it when you are out. also ca be armed by timer for night sleep.
while system is armed, any intruder making his way into the property faces challenge of being detected by sensors tied to your alarm system. motion sensors are usually aimed at possible entrance points (doorways, base of stairs, windows)
other sensors exist to detect broken window etc. one thing with motion sensors is that they can be source of nuisance trips of you are a sleepwalker or have pets. so you may want to aim them a bit higher. but criminals also know this so they may try to stay close to the floor.

 

Thank you for your detailed information. Well, it could be some kind of pre installed system? This kind of sensors cannot be used malliciously, right? They cannot transmit info via radio to some other persons, correct?

No, they just transmit a signal to say they've been activated. Some transmit a 'I'm alive' signal every few minutes so the central system knows they are OK. Usually there's some info about the battery level as well for housekeeping purposes, but nothing that relates to people or location. Unless its a spy camera made to look like a PIR.... but if you believed that then you'd probably be paranoid