Simple Burglar Alarm for Workshop

[Fergie 307]

You could probably repurpose a car courtesy light switch to work on the door with a relay and big horn for something really simple, although unless you incorporate a latched relay then just shutting the door again would turn it off. And if you do use a latched relay then once activated someone would need to reset it.
Another option is just to get a flashing led, you can get 12v ones or self contained units that work off an AA battery or similar. Some "Alarmed" stickers and that may be enough to persuade them to look elsewhere.

 

[Fergie 307]

Dampdog2013 is an e bay seller who does kits. Both my alarms are based on his box. Alarm input is a 12v DC feed, so can be adapted to work with PIR, switches etc. the siren he does is pretty loud, although I have used his output to fire up a much bigger one through a relay.

 

[Chubber]

Don't forget hinge bolts, inexpensive, supplement your locks.

Internal Sonic 'bombs' on a key/hidden switch delay (like some narrowboat owners have)

Sorry, just seen above.

 

[JoeS]

Dampdog2013 is an e bay seller who does kits. Both my alarms are based on his box. Alarm input is a 12v DC feed, so can be adapted to work with PIR, switches etc. the siren he does is pretty loud, although I have used his output to fire up a much bigger one through a relay.

Great recommendation - I'm going to order the light/siren from him.

Got some great ideas on here and I'm going to put something together with a 12v key switch.

 

[JoeS]

Don't forget hinge bolts, inexpensive, supplement your locks.

Internal Sonic 'bombs' on a key/hidden switch delay (like some narrowboat owners have)

Sorry, just seen above.

Good idea on the hinge bolts - just ordered some - great idea.

 

[Fergie 307]

I would spend a couple of quid on a flashing led. You can wire that into the box and mount it on the outside of the building. That way you have a good visual indication when it's live.

 

[Fergie 307]

You can also modify PIR units by gluing a piece of tube on the dome. Reduces their sensitivity and range so they can be used like a proximity sensor. You can experiment with different sizes and lengths of tube. About 10mm ID and 20mm long range reduced to about 6-8 feet and maybe 10°.
Position somewhere that someone needs to walk past to get to whatever you are protecting. Reduced range means much less likely to have false alarms. Handy in situations where a beam isn't practicable.