SparkFun Forums

[Pseudomizer]

Hello guys,

I have tried all commercial solutions out there but the longest one supporting up to 450 feet distance didn't work as there are 2 houses in the line of sight and the mailbox itself being metal, made it fail.

Due to this I am not considering other options. Given that I am new to this here I would like to get your feedback on hardware and implementation. So here we go and again, this is coming from a newbie so I might be completely wrong.

Distance between House and Mailbox is about 300 feet with 2 houses in the line of sight hence me going for the Xbee Pro 900 not taking any chances for distance but also by going with 900 instead of 2.4GHz the penetration of the mailbox and the houses in the line of sight should be easier from what I researched online.
Mailbox is a metal multi-mailbox for multiple houses owned by the HOA and I am not allowed to drill holes into that mailbox.

Hardware ideas:
2 x Arduino UNOs Rev 3
2 x Xbee Pro 900
2 x Xbee Shields
1 x USB to Xbee board
1 x Tilt sensor
1 x 9-Volt Battery
1 x contact sensor

My idea is to build one box with a tilt sensor which will sit in the mailbox. I want to use the contact sensor to power on the Arduino when the mailbox is opened to save energy assuming that there is enough time for the arduino to power on, send a signal before the mailman closes the mailbox again.

Another idea would be to use this contact sensor to not only power on the Arduino but also to notify the primary Arduino but I don't know if this is even possible.

On the target side I want to connect the Arduino somehow to my network and notify my Vera 3 from my home automation system about new mail having arrived.

I read the other threads here but none of them came close to address my problem while the one solution was using WiFi which doesn't apply here as I need long range RF signals.

Any ideas or help is welcome as I don't want to buy the wrong hardware. Thanks in advance guys for any help you can provide.

[uChip]

Before trying to enclose a transmitter in a metal box you might want to Google "Faraday cage". At a minimum, the antenna has to stick out of the box.
Good luck,
- Chip

[Pseudomizer]

Before trying to enclose a transmitter in a metal box you might want to Google "Faraday cage". At a minimum, the antenna has to stick out of the box.
Good luck,
- Chip

Fully aware but the transmission should happen when the mailman opens the door. That's the plan.

[lyndon]

But that means that the receiver has to be in line of sight with the opening of the mailbox. There will probably be some "fringing" around the opening so it doesn't have to be an exact line of sight, but if the mailbox is in front of your house, facing the street, then a receiver that's in the house is not likely to receive a signal.

[stevech]

2.4GHz is the hard way.
Try one of these, high power version, 100mW. Sub-GHz makes a huge difference.
http://www.anarduino.com/miniwireless/

[elevator4]

Agree with Stevech. You may want to look at their -LR models, still sub-GHz, for longest range at a slower data rate, which I assume is of no concern in your application.
As for the on/off switching, you want to wire the box so that the mailman turns it on, the Arduino latches it on until its job is done, then lets it drop. Takes an OR gate or two diodes.

2.4GHz is the hard way.
Try one of these, high power version, 100mW. Sub-GHz makes a huge difference.
http://www.anarduino.com/miniwireless/

[skimask]

1) Take out any mail
2) Leave the door open
3) Mailman puts mail in the box
4) Mailman shuts the door
5) Look out the window see if the door is still open
6) Profit???

Worked for me for years...

[Valen]

1) Take out any mail
2) Leave the door open
3) Mailman puts mail in the box
4) Mailman shuts the door
5) Look out the window see if the door is still open
6) Profit???

Worked for me for years...

First paragraph of first message said he didn't have line of sight.