Seeking Help with Faux Home Security Device for Rented Home

Old 09-28-18, 09:23 AM
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Seeking Help with Faux Home Security Device for Rented Home

I’m currently living and working abroad and want to build a “home security device” for the house we’re renting. The front and side yards are well protected by tall security fences and sizable dogs whom have free run of the interior perimeter at night.

The home is situated on (and against) a hill, such that the rear edge of our roof is only four feet above the ground when standing on the hill behind our house — easy to hop up and walk up to the peak of the roof and down the other side. This hill area directly behind our house is our neighbor’s abandoned kennel with fence and gate in disrepair so local teens come and go to drink and party because the kennel is surrounded by thick rain-forest and affords a lot of privacy. The home’s current tenant doesn’t care about the fence, gate or teens. I don’t necessarily have a problem with their hanging out back there, as long as they don’t climb up on our roof.

Most of the break-ins and home robberies in this neighborhood are crimes of opportunity — impoverished, desperate people or drug addicts looking for items to steal and sell. Any hint of a reasonable home security system, cameras, etc., scares off 98% of potential perpetrators and while we have cameras on the front and sides (complementing fences and dogs), putting a camera on the roof in back might not be the best idea. Ironically, with no place to mount it out of reach, it could be stolen.

Given that 98% of potential perpetrators don’t want to be seen or captured on video, I’m thinking of putting a real PIR-triggered motion system that behaves like an image-capture system — something small and sturdy that can be anchored to a fascia board on a dormer near the peak of the roof. The roof tiles extend a few inches beyond the fascia so though outdoors, any unit attached to the fascia board would be protected from rain and sun. A PIR sensor or device mounted on this fascia would have a clear view of any trespassers attempting to gain access to the roof from the area behind our house.

What I have in mind, is to take a short piece of 3” (diameter) PVC pipe and fabricate a string of LED lights around its inside circumference at the front edge, complemented by a piece of dark, convex plexiglass mounted in its center to simulate a camera lens (surrounded by LED’s). The LED’s would be driven by an actual strobe circuit triggered by the PIR – set for the minimal 5-second “on” duration (PIR Delay setting).

The PIR would simultaneously trigger an MP3 audio player (circuit board) containing a brief audio sample of a camera shutter, firing in rapid succession (timed to match the strobe blinks). The presence of the plexiglass “lens” (easily visible during the day) in tandem with the strobe and sound effects (at night) would give trespassers the impression they’re being photographed numerous times any time they trigger the system. (A second “email sent” sound effect could follow the “shutter snaps” such that trespassers think the images are being uploaded immediately to the internet. I’m not worried about arming the system during the day. The roof is easily visible to all passersby during the day. The PIR would only need to be active from dusk till dawn. I believe the device, easily visible from about 28 feet away (distance to rear edge of roof) during the day would fool potential trespassers and prevent them from attempting to climb up on the roof at night.

The mp3 audio system (project board/enclosure) and speaker could be mounted under the eaves of the dormer hidden from view and the weather.

It would be best if the PIR could reset immediately after its 5-second “on” cycle so that it’s ready to trigger again immediately upon completion of the 5-second “on” cycle.

Conveniently, there is a 220V outlet located under the dormer which could power everything, with the understanding that voltages would likely have to be stepped down/converted, to power specific components according to their specifications.

My biggest question is about where to buy or how to build the strobe circuit. Would the big capacitors generally associated with strobes be required if I’m powering the entire system with 220V? My preference would be to locate the strobe circuit and components inside the PVC pipe behind the LED’s, and mount the PVC pipe to a flange on the fascia board. The length of the PVC tube/housing should be no more than 3.5” such that it remains sturdily attached to the fascia (hard to steal) and well-protected from weather by the overhang.

The strobe would need to be powerful, but would only have to blink for 5 seconds or so.

I imagine one could use a pre-built PIR device (available in many hardware stores) and wire it’s trigger/output to the strobe circuit and the mp3 player circuit. One could probably also buy a simple PIR component and wire it along with the mp3 player board into the same weather-proof enclosure. I’m open to any and all suggestions.

Currently I am living in South America and while there are hardware and electronics stores in this city, we don’t always have access to as many brands as are available in the USA. That said, I have friends whom can purchase items in the US and bring them to me when they come to visit.

Please bear in mind, that I don’t have a lot of experience designing or wiring electronics but I can solder pretty well and I’m handy with audio tech.

Any suggestions and guidance would be greatly appreciated. Thanks!
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