Logan Buchalter
Natural Sunlight Alarm Clock
Electrical Engineering, Northeastern University
Relevant Skills: circuit construction, logic gates, op-amp configuration
Objective
Design and produce a circuit to solve a chosen everyday issue. For this project, my group and I decided to tackle the disruptive nature of alarm clocks.
Variables / Constraints
The circuit and corresponding hardware needed to incorporate concepts from the electrical engineering course. We chose to incorporate comparator op-amp circuits and logic gates.
Design Process
[1] We began by constructing a logic diagram to show all possible inputs and their desired outputs. The 3 inputs (1 light dependent resistor outside, 1 in the bedroom, and a pillow pressure sensor), corresponded to 8 potential cases. I transferred this logic into a logic hardware circuit composed of 2 comparator op-amp and 2 AND integrated circuits.
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Circuit logic diagram
Logic hardware diagram
[2] I assessed the components we had on hand and decided to construct the comparators from an IC TLV2462CP dual op-amp chip and the AND gates from an IC 9N00/7400 quad NAND chip. With this information, we were able to construct a complete circuit diagram, complete with a small motor to actuate the blinds and let sunlight in. The circuit was constructed, and I wired the op-amp and AND chips. Before setting up the motor, I performed logic testing with LEDs to validate performance. To fine tune the comparator sensitivity, we changed pulldown and comparator resistor values.
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Circuit diagram with finalized resistor values
Circuit architecture with LEDs to indicate inputs and outputs
Solution
After validating circuit performance, I connected the motor, constructed a housing for the circuit, and designed / 3D printed photoresistor covers to help with demonstration. The finished product functions as intended, and provides a feasible alternative to waking up to an alarm by allowing the user to gradually wake up to natural sunlight.
Circuit housing with 3D printed pieces, mounted motor