Seeker
22-02-22, 01:45 PM
I have a bedroom at the back of the house which would be the ideal room for a break-in. It's not visible from the road, nor is it overlooked. I have an alarm but that would only be triggered by the time the window had been broken, I wanted an approach deterrent.
A security light would be an (obvious) option and I have the pieces of an old one which I kept and still works but it would mean running power outside - too much faff (it's a Dormer bungalow and the attic(s) aren't easy to move around in) and the previous owner had broken the ring main somewhere and I'm wary about adding any more load, however low it might be.
The PIR sensors don't work through glass, I tried it anyway, and they don't. You can buy inexpensive microwave motion detectors from ebay, so I ordered one, hooked it up and it does see motion through glass. It also has a light detector so it can be set to only work at night.
The microwave motion detector is omni directional which means it will keep triggering if I'm in the room so my current plan is to fit the detector in a small box which will have a Faraday shield on 5 sides. I've ordered adhesive copper tape for RF/EMI screening (didn't know that was a thing) which I'll use to line the box and ground it to earth. A quick test with aluminium foil proved unsuccessful but it wasn't grounded.
I had a quick look for the microwave oven door mesh but I haven't found any yet and ovens work at about 2.5Ghz and the motion detector is twice that. Let's see what happens with the cage. :)
A security light would be an (obvious) option and I have the pieces of an old one which I kept and still works but it would mean running power outside - too much faff (it's a Dormer bungalow and the attic(s) aren't easy to move around in) and the previous owner had broken the ring main somewhere and I'm wary about adding any more load, however low it might be.
The PIR sensors don't work through glass, I tried it anyway, and they don't. You can buy inexpensive microwave motion detectors from ebay, so I ordered one, hooked it up and it does see motion through glass. It also has a light detector so it can be set to only work at night.
The microwave motion detector is omni directional which means it will keep triggering if I'm in the room so my current plan is to fit the detector in a small box which will have a Faraday shield on 5 sides. I've ordered adhesive copper tape for RF/EMI screening (didn't know that was a thing) which I'll use to line the box and ground it to earth. A quick test with aluminium foil proved unsuccessful but it wasn't grounded.
I had a quick look for the microwave oven door mesh but I haven't found any yet and ovens work at about 2.5Ghz and the motion detector is twice that. Let's see what happens with the cage. :)