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Sunday, January 30, 2011

Project Blog

Friday, January 28, 2011

The mail notifier

In order to ease the work for the local postmen in Denmark where I live, the government decided that apartment complexes should install mailboxes on the ground level, so the postmen would not have to run up and down stairs many thousand times a day. This is a good deal for the postmen, however it also means that I have to check my mailbox daily if I want to be up to date with the mail I receive. The dilemma is this: I could go and check my mailbox daily, but if my mailbox is empty that would be a waste of time and just plan irritating. On the other hand if I only check my mail say every 3 days then I might miss something urgent that needs my attention.

So I decided to build a small system that could notify me whenever someone had dropped something in my mailbox. To ease the build I brought a cheep wireless doorbell for its wireless capabilities. The plan was simple. Mount the transmitter part on the inside of the mailbox and extend the pushbutton with some wires and a microswitch to detect when the lid is open. The “new mail” notification would then be handled by means of a blinking LED on the doorbell receiver unit placed in my apartment.
To remember if the mailbox lid had been opened I made a electronic flip-flop that was set when the lid is opened and reset when a small reset pushbutton was pressed.

This is the logic schematic for the little addon board I made for the doorbell unit.


This is a pretty neat setup. I would like to have one for my Mail Box too. Even though I live in a Rural Area with the Mail Box at the Curb. No Stairs to climb. But hey, sometimes it Cold Out Side!;)


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