1. When does mail arrive in my mailbox? Engineering Design Process Mark Eimer and Josiah White

2.  Remove unnecessary trips to the residential mailbox so that mail is retrieved during the first trip Define The Problem

3.  Sensor to indicate that the mailbox door has been opened or detects the weight of mail inside the mailbox  Flag that indicates that mail has been delivered  Wait until 9PM to get the mail  Create a mail delivery service from the mailbox to the home  Train an animal to retrieve the mail Brainstorm, Research, and Generate Ideas

4. Identify Criteria and Specify Constraints  Criteria  Simple and easy to use  Reliable and predictable  Affordable  Installed by the home owner  Easy to maintain  Discreet in appearance and notification  Constraints  Cost no more than $100  Cannot obstruct the delivery of mail  Needs to work with any USPS approved mailbox  Solution should meet the needs of handicapped residents

5.  Sensor to indicate that the mailbox door has been opened or detects the weight of mail inside the mailbox  Flag that indicates that mail has been delivered  Wait until 9PM to get the mail  Create a mail delivery service from the mailbox to the home  Train an animal to retrieve the mail Develop and Propose Designs and Choose Among Alternative Solutions

6.  A photosensitive sensor was chosen due to costs and simplicity. Some sensors have moving parts, which reduce reliability over time. Motion sensors and accelerometers are much more expensive than light sensors.  The receiver can be configured to notify the owner via different methods. A sound can play or a light can be turned on (or both). In addition, the receiver can even be configured to have a mechanical response that is tied to a motor.  Neither the transmitter or sensor have a requirement for power provisioning. Either can run on a battery system, a small solar panel with a battery backup, or be hardwired to a power source located elsewhere. Implement the Proposed Solution

7. Make a Model or Prototype Model is a three part system comprised of a light sensitive diode, a transmitter, and a receiver. Image courtesy of: http://transistron.com/ Image courtesy of: http://www.electrodragon.com/

8.  Compared to other systems on the market that serve the same purpose, this system is remarkably cheaper. Off the shelf pricing places this design at less than 50% the cost of other, similar systems.  Other systems use potentiometers that are only triggered when the door is opened to a certain degree. By using a highly sensitive photodetector, as long as it isn’t night time, the sensor will always trigger, regardless of if the door was opened completely.  Photodetector systems are very compact and use very little energy. This allows for a small form factor and a power system that can either be smaller or longer lasting. Evaluate the Solution and Its Consequences

9.  Because the sensor has to be exposed in order to detect light, there is an increased chance of damage when compared to other enclosed systems.  Transmission distance is reliant on many external factors that may cause interference. Evaluate the Solution and Its Consequences

10.  The system must be placed inside of the mailbox close, or attached to, the door itself for optimum results.  Transmission range directly proportional to power used. A 9v battery will provide transmission distances of 200-500 feet depending on environmental conditions. Refine the Design

11.  Final design will be very compact. Photodetector sensor located at a corner of the main face of the device to allow the most freedom in placement options.  Can be attached either via magnet, adhesive backing, or screwed into mailbox itself.  Receiver would have option for light/sound notification. Would have a reset switch to prepare for the next notification. Create the Final Design