Mailbox Detector
This circuit is live in Circuit Canvas. Open it to explore every part and wire, or make your own copy to change values, swap parts and build your own version. Free, right in your browser.
This is a simple project that detects when you got mail!
To build it, you need to place a permanent magnet in the lid of your mailbox. And you need to place the reed switch so that it's near the magnet when the lid is closed, but away from the magnet when the lid is open.
The LED will turn on after the mailman has opened and closed the lid of your mailbox, indicating that you've got mail!
Mailbox Detector Schematic
The circuit is based around the reed switch opening and closing, thereby creating a clock pulse to the D flip-flop, which will set the Q output HIGH. When Q is HIGH, the LED turns on.
To reset the circuit after getting your mail, add a pull-down resistor from the RESET pin down to minus, and a pushbutton from the RESET pin and up to plus.
Mailbox Detector Parts List
How to Build the Mailbox Detector
Here's how you can build this circuit on a perfboard. The brown lines indicate solder bridges between the pads.
Make it your own
Every circuit here is a live project in Circuit Canvas, not just a picture. Copy this one and change a value, swap a part or move it to a stripboard: the schematic and the breadboard layout are linked, so a part added to one appears in the other.
Or start from a blank canvas and draw your own circuit, with thousands of ready-made parts.