Note: Patent Pending on everything shown on these pages!
About The Project
Part 1 – The Mechanical Flag System
What It Does: Provides a visual indicator (flag) to signify that the mail has been delivered. Background: I thought it would be useful to know if the mail had been delivered before going out to the mailbox.
Challenges: Determining how to add functionality to the mailbox without disturbing its appearance. My goal was that the mailman would be unaware that the mailbox was modified. i.e. nothing contained inside the mailbox or interfering with the door.
What I Did: The key to making it work was discovering that there is a good 3/4" dead space beneath the mailbox and that the bottom of the mailbox door moves about 3/4" backwards, underneath the mailbox, when the door is opened, due to the way it is hinged. To take advantage of that space:
I hinged a plastic "flag" so that it would drop down behind the mailbox.
I attached a rod to the bottom of the mailbox door so that the rod would be pushed back ~3/4" when the door was opened
A magnet attached to the rod holds the flag up when the door is closed and drops the flag wnen the magnet is pushed back.
How It Works: Sequence of Operations:
When he mailman opens the door, the rod is pushed backwards which causes the flag to drop.
After retrieving the mail and closing the door, the flag is manually lifted to the up position where it is held in position by the magnet.
AWS Button - Before modification
Part 2 – Adapting an AWS Button to Send a "You've Got Mail" Text Message What It Does: Utilizes the Amazon Web System (AWS) to send me a text message when the mail has been delivered.
Finding a way to perform an automated "short-press" of the AWS* button. See note 1
To send a text when the mail is delivered and not when the mail is retrieved. See note 2
Gaining an understanding of IOT**
What I Did: I opted to use a relay to trigger the AWS module.
After opening the AWS button, I found where I could connect 2 wires to trigger it.
These wires are then connected to the relay's "make" contacts.
Operating the relay in series with a capacitor causes the relay to operate and release quickly generating a "single (short) press".
I re-used the mechanical flag from above.
Because the Mechanical Flag, from part one above, already had the functionality of operating on mail delivery and not with mail retrieval, I made use of that functionality by placing a mercury switch on the back of the flag which connects a 9 volt battery to operate the relay.
A second mercury switch, facing the opposite direction, discharges the capacitor when the flag is put back up.
How It Works:
The first opening of the door causes the Mechanical Flag to drop.
The mercury switch on the back of the flag closes and sends 9V to the relay through a capacitor which causes the relay to operate and release. (The same as a button "Short-Press")
The relay contacts trigger the AWS system which then runs a Lambda*** script to send a text message to my phone.
The AWS button can respond to a "Single (short) Press, "Long-Press" or "Double-Press". See example Lambda Script below.
Pressing the button for more than 6 seconds erases the its programming.
Opening the door to retrieve the mail does not trigger a second text message because the flag is already in its dropped position.
---------------- * AWS = Amazon Web Service: a cloud computing platform from Amazon that provides customers with a wide array of cloud computing services. ** The Internet of Things (IoT): “Connecting various devices through the internet in coordination with each other to perform one or more tasks. ‘Things’ can be electronic devices, sensors, network peripherals, signal flow switches, and actuators.” *** AWS Lambda is a computing service that lets you run code on their server.