Intruder alarm.

Hi everybody..

Forgive me for what is, looking around this forum, a pretty basic question, but I need help with this, I live in a very remote part of the UK and have been broken into and had many 1000's £ of tools and equipment stolen from me, TWICE in 7 days. I am a target now and need to defend what I have left.

I am trying to make an intruder alarm that will power a VERY loud siren (130db) and a strobe light or two, all run from large (120Ah) 12v battery. I cannot use 240v.

The siren and lights need to be triggered by a PIR motion sensor.

Does anyone have any experience of doing this?

What components do I need (PIR and Arduino + relay?)

Can anyone draw me a simple diagram for how to wire this up?

Even a sketch on paper, then a photo taken and posted is fine.

I am not an electronics guy, nor an engineer, but I can follow clear instructions with care and attention.

I read on another thread that the Arduino boards have a voltage sensor that can take 12V. Will a fully charged 12v battery, which maybe has almost 13v in it be a problem?

Many thanks for your help!

lupussonic:
I am trying to make an intruder alarm that will power a VERY loud siren (130db) and a strobe light or two, all run from large (120Ah) 12v battery. I cannot use 240v.

Can you provide links to the siren, strobe light, and battery? That will help us help you greatly.

lupussonic:
The siren and lights need to be triggered by a PIR motion sensor.
Does anyone have any experience of doing this?

Yes, this project shouldn’t be that difficult.

lupussonic:
What components do I need (PIR and Arduino + relay?)

Without the links to the external equipment such as the siren, I can only make a guess: Yes, it is likely you will need a PIR sensor, Arduino, and two relays. NOTE: Don’t forget you’ll need wire/wire strippers - maybe even a soldering iron. May also need a couple of resistors.

lupussonic:
I read on another thread that the Arduino boards have a voltage sensor that can take 12V. Will a fully charged 12v battery, which maybe has almost 13v in it be a problem?

13V might be a problem, but I doubt it. To be sure, you can use a voltage divider to feed 12V max to the Arduino.

lupussonic:
Can anyone draw me a simple diagram for how to wire this up?

Attached. :slight_smile:

Attached.

IMG_1411 (2).JPG

Are there cats, dogs, farm animals, tree limbs blowing in the breeze, that will cause false alarms? A voltage divider is not the best way to reduce voltage for power, a switch mode supply to buck down to 9V would be better.