Letterbox mail detection

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Letterbox mail detection

neb

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#287121 8-Jun-2021 02:51

Since our mail deliveries are quite erratic I've been toying with the idea of some sort of LoRa-based mail sensor for the letterbox. At the moment the least awful option seems to be a plastic (i.e. lightweight) piano hinge across the mail slot with a magnet taped to it that activates a reed switch when a letter is pushed in, which pushes the hinge from the open to the closed position and drops the magnet down next to the switch. This seems like a bit of a kludge, but I can't think of anything better at the moment... does anyone have any better ideas? Note that it can't use active electronic sensing like an IR sensor since it has to run off AA or similar batteries for months if not years, thus the LoRa use.

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#2720494 8-Jun-2021 06:30

Simply don't get enough post to make it worthwhile.

But I do have an external video camera that covers the post-box and the front garden. Did have notification enabled, but disabled this and only review the recording whenever I want.

Goosey

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#2720499 8-Jun-2021 06:59

Wouldn't a traditional "flag" work... posties would know how to use this...

Nuisance would be the junk mail people... or kids having a laugh.

richms

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#2720503 8-Jun-2021 07:13

Why LoRa and not just normal 433MHz or a wifi door/window reed switch sensor?

Richard rich.ms

Ge0rge

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#2720510 8-Jun-2021 07:20

Goosey:
Wouldn't a traditional "flag" work... posties would know how to use this...

Nuisance would be the junk mail people... or kids having a laugh.

The flags are for rural deliveries, and you put it up so the postie knows there is a letter in there that you want them to take. I somehow can't see a townie-postie touching the flag at all.

MuzaNZ

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#2720638 8-Jun-2021 11:10

The way i've gone about doing this is using a IR sensor connected to a Modbus RTU module which in turn communicates with home assistant via an ethernet to rs485 adapter.

This is also connected to the gate controller via a relay so home assistant can have control over them as well.

Then using an automation in home assistant a push notification is sent to my phone when the mail is delivered.

This option does require running ethernet out to the end of your drive though, but i'm sue you could find a wifi to rs485 adapter.

tecnam2003

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#2720653 8-Jun-2021 11:31

tried this but gave up after writing and mailing 27 letters to myself to fine tune and calibrate it..

😄

catdog

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#2720736 8-Jun-2021 15:37

I have a smartthings multipurpose sensor stuck on the back of the mail flap with double sided tape. Initially I tried using the sensor's motion detection feature, but found that it was too sensitive (rain or wind would cause enough vibration to trigger it) and I couldn't find a way to adjust the sensitivity. So I have now mounted the magnet inside the mailbox so that the sensor moves close to the magnet when you push the flap open. It's still not perfect as sometimes the mail person will only push the slot just enough to slip the letters through, rather than pushing the flap hard all the way open.

The sensor uses Zigbee and lasts about a year on its coin cell battery. I have it connected to Home Assistant (zigbee2mqtt), but found that the signal strength was marginal out to the mail box. I added a router (i.e. repeater) powered from an old USB cellphone charger plug, located in the corner of the house closest to the mailbox, which fixed the signal strength.

rogercruse:

Simply don't get enough post to make it worthwhile.

That's why it's useful. If you get lots of mail, then you tend to check it often. With a notification, the occasional important letter isn't sitting there for a week before I notice it.

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KrazyKid

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#2720738 8-Jun-2021 15:43

For me this is definitely in the fun to make, but I'll never need category.

I have to walk past my letterbox to get to my door and when I check it there is nearly always nothing there...

... Because the wife and 2 kids have each checked it already :)

Ge0rge

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#2720751 8-Jun-2021 16:01

My letter box has a large flap that folds down at the front. It stays open pretty much all the time, unless the postie puts mail in there - then they close it. Flap closed? Got mail. Remove and leave flap open.

frankv

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#2720768 8-Jun-2021 16:22

catdog:

I have a smartthings multipurpose sensor stuck on the back of the mail flap with double sided tape. Initially I tried using the sensor's motion detection feature, but found that it was too sensitive (rain or wind would cause enough vibration to trigger it) and I couldn't find a way to adjust the sensitivity. So I have now mounted the magnet inside the mailbox so that the sensor moves close to the magnet when you push the flap open. It's still not perfect as sometimes the mail person will only push the slot just enough to slip the letters through, rather than pushing the flap hard all the way open.

Add some weight to the flap to reduce the sensitivity to vibration. That might be enough to make the postie push harder to open it. If you make the flap longer, so that it extends well below the bottom of the mail slot, the postie will have to lift it by a larger angle to be able to put a letter in. If it was infinitely long, the postie would have to lift it to near 90 degrees. Or a spring to make the flap bi-stable, so that once it's pushed over-centre it goes all the way. Except that then it would stay open and let the rain in.

A software approach to the vibration would be to require the flap to be continuously open for (say) 1/2 a second before it is confirmed as triggered. This is a standard technique called "debouncing". Or you can do it with a Resistor/Capacitor if you want to do it electronically.

djtOtago

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#2720772 8-Jun-2021 16:33

If you make changes to your letter box, make sure you comply with the NZ post specifications.

https://www.nzpost.co.nz/personal/receiving-mail/mailbox-specifications

neb

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#2720860 8-Jun-2021 18:40

richms:
Why LoRa and not just normal 433MHz or a wifi door/window reed switch sensor?

Because I've got LoRa set up and it's, as the name says, long range and very low power so can run off batteries more or less forever. It has to be wireless since there's a ton of stuff between the house and letterbox and no way to run a cable (see the Chorus fibre thread elsewhere on here).

neb

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#2720861 8-Jun-2021 18:43

djtOtago:
If you make changes to your letter box, make sure you comply with the NZ post specifications.

https://www.nzpost.co.nz/personal/receiving-mail/mailbox-specifications

More specifically, it's EN 13724, which Standards NZ cites and will sell you for about $450, or just over ten dollars a page.

richms

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#2720867 8-Jun-2021 19:02

neb:
richms:

Why LoRa and not just normal 433MHz or a wifi door/window reed switch sensor?

Because I've got LoRa set up and it's, as the name says, long range and very low power so can run off batteries more or less forever. It has to be wireless since there's a ton of stuff between the house and letterbox and no way to run a cable (see the Chorus fibre thread elsewhere on here).

Well in that case I would just do what the swiss accent guy has done here https://www.youtube.com/watch?v=WV_VumvI-0A - I am quite happy with the wifi door and window sensors that I have for battery life so would just use one of them for the job.

Richard rich.ms

neb

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#2720878 8-Jun-2021 19:29

The issue isn't the tech but the mechanical side of things, i.e. how to turn a mail delivery event into an electronic signal. The piano-hinge + reed switch just seems like a bit of a kludge, and prone to being finicky with triggering.

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