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# 251027 5-Jun-2019 15:07
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Our letterbox isn't much fun to get to when it's raining, or even after it's rained (wet foliage), so I'd like to get some sort of mail-delivery alert system to eliminate unnecessary trips. Problem is there's very little around, there are explicit mailbox alert systems but they all seem to be based on US dropdown-door letterboxes and use either tilt sensors for the door or reed switches. There have been a variety of proximity-sensor based ones that tried to get crowdfunded and failed, and beyond that there's generic motion detectors which all seem to be PIR and therefore won't work.



Does anyone know of any sensors for letterboxes that work on generic slot-type NZ letterboxes? Ideally one that sends an alert via email or to an app, since repurposed motions sensors for driveways or shop doors, if you can find a non-PIR one, require that you be within audible range of the receiver to hear the alert.

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  # 2252137 5-Jun-2019 15:13
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Many ways you can do it, hall sensor, push button etc.




is a ton of projects out there that simply use ESP8866's



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  # 2252138 5-Jun-2019 15:21
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I was really looking for a ready-made solution, for something like house maintenance or woodworking I don't mind tinkering but for this, where there are a range of products in the $20-50 range that almost fit the bill it's just not worth the hassle, even just the cost of the parts once you factor in a weatherproof enclosure, battery, mounting hardware, etc, is going to be more than that, and that's assuming labour is free and takes zero time.



Edited to add: Having followed several (failed) crowdfunded projects that tried this in the past, there's a fair bit of engineering and a lot of time involved, so I'm not keen on recreating one of those from scratch.


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  # 2252142 5-Jun-2019 15:25
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you mean like


Good luck getting the postie to actually use it though....

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  # 2252143 5-Jun-2019 15:29
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I'd use a cheap door alarm, as used in shop doorways, with a remote buzzer. Mount the sender under the top of the mailbox pointing down, and the reflector on the floor of the box.

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  # 2252145 5-Jun-2019 15:34
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Would Wyze Sense be an option for you?


I'm not sure if your mailbox has (or could have) a flap across the posting hole (which would potentially allow a sensor to be connected to the flap and to the side of this), as it'll certainly not work if it's just a hole; nor how far away your mailbox is from your home, but it seems that a number of people have got the Sense working for this purpose.



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  # 2252149 5-Jun-2019 15:41
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neb:, for something like house maintenance or woodworking I don't mind tinkering .

So build a better letterbox/shift existing one to better location :)

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  # 2252199 5-Jun-2019 16:13
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I would go ESP8226 (wemos d1 mini is simplest), with an LDR - assuming it's dark in the mailbox until the lid is opened? If it's not dark, or the light won't change, then I would mount a SR04 at the bottom of the mail opening and measure the distance.


Would take all of 5 minutes to build, and probably an hour to fit in to the mailbox all nicely.


Either way, load of ESP Easy (no screwing around with arduino code), trigger notifications as you please - for me that would be via MQTT and my Node Red server, but you could do pretty much anything you want.


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  # 2252205 5-Jun-2019 16:40
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The biggest issue with most of these solutions is how your get power to the letter box. Even if it’s only 5v/12v.

I was using a battery powered xiaomi contact sensor for a similar purpose until recently. I think the range became too much for it.

Also I’d build a d1 mini based contact sensor, similar as mentioned above. But without a ready means of getting power to it (and no desire to dig up all my paving to run ethernet to it). It died.

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  # 2252220 5-Jun-2019 17:02
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ZWave contact sensor will provide the best range of the lot and you can have a repeater plugged inside the house as close as you can to the contact sensor to provide good consistent range.

Do whatever you want to do man.


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