DIY burglar alarm using cheap PIRs, soldering iron and PC ?

Question

Hello -I'm currently adding a bit of security to my house by buying some cheapwireless PIR sensors and receivers from , interfacing a  PCto them, and switching on lights, sending email alerts, posting webcampictures to a website, etc. when activated. It's going well so far.I'd be interested to know if anyone can see pitfalls in this approach, eg.- PIR manufacturer going out of business and not being able to getcompatible receivers/transmitters- burglars who carry radio jammers (does this happen outside of crimenovels?)- What am I losing by not using sensors intended for alarm systems- Are inconspicuous PIR sensors less of a deterent than a big bell-box?- I'm thinking of installing one of these at a property that already has an"Anglian" branded wireless alarm system - are they likely to clash?Thanks

VisionSet · Accepted Answer

What are you doing for the data logger?

Owain · Answer

Microsoft or Linux based OS? ;-)Quite possiblyUnlikely. More likely to hack your kernel these days.Internal PIR sensors are no deterrent. By the time Mr Scrote The Thieving Scumbag is close enough to see your PIRs he's in your property.Gawd knows, but why not rip the whole lot out and install a proper wired alarm system for a fraction of the price.Owain

VisionSet · Answer

So you have your PC on all the time.  I'd definitely want to avoid that ifpossible.

Simon · Answer

I use the PC's serial port to monitor the state of the wireless receivers,Java to poll the port, send the alerts and control the webcams, and adatabase to log the data. It's very DIY.

VisionSet · Answer

If you are doing it in Java then why not buy a board with JVM on it.  about50 quid, (prob less now).  It comes with a one wire port for yourinterfacing.

Andy Hall · Answer

Microsoft doesn't make any OSes.....

Simon · Answer

The standalone mains-powered PIR sensor has a row of Knight-rider style red LEDS, which should attract the attention of anyone peering in through a window. OTOH, they'd look silly and possibly reduce security if the PIR was installed outside.

meow2222 · Answer

An old P1 laptop sounds like a good candidate, pref with a backupspare.NT

Harry Bloomfield · Answer

Simon explained :Buy enough plus spares.Extremely unlikely, even if they already knew about the special system.I would suggest the biggest pitfall is likely to be the reliability of the PC itself - the likelyhood of it crashing. For really critical stuff which needs to be able to restart the system should it crash, consider a 'watch dog' system. PC sends a regular pulse signal out to a discrete 'watch dog' circuit, if the circuit fails to see a regular pulse from the PC, it reboots the PC. The pulse is generated by the PC from running software, sent out via a bit on one of the ports.Nothing to stop you adding a big bell box and flashing lights.Clash, unlikely if the PIR uses the PC wireless network frequencies 2.4Ghz and the Anglian 432Mhz licence free - no.

Harry Bloomfield · Answer

It happens that Simon formulated :What about mains failure? No mains, no working alarm system.

Owain · Answer

By the time Mr Bawbag The Burgling Bastard is close enough to peer into your windows he's also close enough to steal your carkeys or pour petrol through your letterbox.

You'd probably be better off with gravel and pyracanthus in the front garden.

You could put the Knight-rider style LEDs into a dummy bell box though.

Owain

DIY burglar alarm using cheap PIRs, soldering iron and PC ?

Join the Discussion

Didn't find your answer?