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.
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.
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