1. Alarm Sounds When Refrigerator Door Remains Open Too Long Design Review 2 By Chi-Weng Kam Dan Strengier May 20, 2009

2. Design Requirements (Circuit) Modify the design idea of refrigerator alarm into a more user-friendly and sustainable product. (lower power consumption) Alert user when fridge door is open for more than 15 seconds DC battery operation, 3 – 10V. The lower the better. Create an easy to implement circuit for consumers, i.e. no dangerous and difficult interfacing with fridge circuitry and switches Sound level of the alarm is between 70dB and 80dB. Minimum space requirement (3'' X 5'' X 0.5'') with wire length (1 feet max if wire is used) Cost ($4.00 for the prototype, not including the cost of batteries) Babu, T.A. "Alarm Sounds When Refrigerator Door Remains Open Too Long." Electronic Design 26 Mar. 2009. 06 Apr. 2009 http://electronicdesign.com/Articles/ArticleID/20806/20806.html

3. Adequately test all possible door opening configurations - simulate fridge door open through a voltage pulse. Duration of pulses and frequency determine all possible combinations Determine total power consumption for overall performance during all simulated fridge door openings, including off state. Design Requirements (Labview)

4. Adjusted Requirements 15 second timer instead of 20 seconds Size requirement 3”x5”x.5”is now 3”x5”x1”

5. Implemented Circuit

6. Design Specifications (Version 1) Sound level of the alarm is between 70dB and 80dB. DC battery operation (between 3-10V). Minimum space requirement (3'' X 5'' X 0.5'') with wire length (1 feet max if wire is used) Cost ($4.00 for the prototype, not including the cost of batteries) Babu, T.A. "Alarm Sounds When Refrigerator Door Remains Open Too Long." Electronic Design 26 Mar. 2009. 06 Apr. 2009 http://electronicdesign.com/Articles/ArticleID/20806/20806.html Sound Levels: http://www.eie.fceia.unr.edu.ar/~acustica/comite/soundlev.htm Design Priorities: 1. Safety (modify from AC-powered circuit to a DC-powered circuit) 2. Power Dissipation 3. Cost 4. Ease of use 5. Size

7. Questions? Feedbacks and Suggestions

8. Origal Design Idea – Refrigerator Alarm Issue with the original design: ◦ High Power Dissipation through the AC-DC Rectifier – heating of the Zener Diode. ◦ High AC Voltage Operation; Require certain technical knowledge in order to retrofit the circuit to the refrigerator – Not User Friendly. Babu, T.A. "Alarm Sounds When Refrigerator Door Remains Open Too Long." Electronic Design 26 Mar. 2009. 06 Apr. 2009 http://electronicdesign.com/Articles/ArticleID/20806/20806.html