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Forum Index : Electronics : Rotating PIR - 12VDC - Intruder alarm suggestion please!
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| domwild Guru  Joined: 16/12/2005 Location: AustraliaPosts: 873 |
Hi, Aliexpess is selling lots of 220VAC (no good!)to 12VDC rotating PIRs for a few Dollars, while the builder wants $400 for one, but connected to an alarm panel. Having been burgled recently I would like to be notified if someone breaks the beam at the gate. Those PIRs seen to have three wires and I do not expect the Chinese dealer to have a clue how to connect the output of them, not even in Chinglish! Am speculating there is one plus and minus for the 12VDC supply and the third wire with 12VDC output for the break indication? Cheap system: The "break" output could then be connected to a bell; a siren would upset the Fleabay courier or visitors. Dearer system: A 4G Telstra dongle is supplying WiFi 24/7. Wouldn't it be nice to get a Wifi notification on the "break" output? Is there a "box" to interface with the "break" output? Any comments to the two systems? Thanks. Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up. Winston Churchill |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
We have used these beam sensors to detect people walking through a gate, driveway. They come as a sender and receiver unit, run off 12v and have a relay with NO,NC contacts. Whenever the IR beam is broken the relay pulls in.Beam Sensor Range is 3 to 10m outdoors. There are other ones on AliExpress with bigger dual lenses, that have ranges approx 100M Cheers Mike |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Here is an explanation of how passive infrared sensors work: https://learn.adafruit.com/pir-passive-infrared-proximity-motion-sensor/how-pirs-work There is a bit more to it than just the actual small three wire sensor itself. It requires a high gain two channel amplifier, and some rather carefully chosen time constants. You don't want to set off an intruder alarm every time the sun comes out from behind a cloud for example. The better commercial motion sensors combine both a microwave doppler system with passive infrared detection. These cannot be set off by just motion, such as wind blown foliage, or by sudden ambient temperature changes such as passing clouds. But if the motion sensor detects both occurring together, its very likely an animal or a vehicle. There is a fair bit of hardware and complexity inside a high quality motion sensor, which is why the really good ones that don't create a bunch of false alarms can be rather expensive. Cheers, Tony. |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 438 |
Different technology, these are what I use at home. Door bell with cam Wyze |
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| Killian45 Newbie  Joined: 27/12/2019 Location: United KingdomPosts: 1 |
I can recommend this securinghome.com alarm system for such purpose. I've purchased it not so long ago and can say it's doing a great job. In my opinion, it's the best option of all, as it has some extra options, such as connection with crime prevention centers or home security advisor services. |
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