just looking at an alarm for my shed.
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=101422&ts=63168&id=92633
Wondered if anyone with any knowledge thought it would be possible to connect to a mains supply (guessing its batteries) and if i would also be able to connect a normal PIR aswell as the door contacts to it?
The device IS battery operated, this is detailed in the instruction manual. You could always use a rechargeable PP3 battery if you are concerned about battery consumption. The equipment will not be suitable for connection to the mains without a rectified transformer output of the correct power. You would also need a suitable fuse in the circuit, so that you dont burn the shed down in the case of a fault. Bear in mind that it may cost you a disproportionate amount to alter the equipment. Connecting a PIR does not seem practical with the existing arrangement, although it is possible in principle.
My opinion? Don't bother.
Bit of an overkill, but my company sells SMS text based alarm units. We've never sold one to monitor a shed though. Connect up to 4 PIR's, door switches to the unit - stick a SIM card in it. It'll send you a text message direct to your mobile if an alarm occurs - so you can get down there sharpish with a baseball bat.
You can also connect a temperature sensor to it, so you could use it for frost detection aswell....