Transcript
Ultra-Modern Clock Hung-An Ting(丁泓安), Chun-Cheng Chu(朱峻成) TA: Ji-Lin Jou (周基霖) Advisor: Lin I (伊林) Experimental Physics I, Department of Physics, National Central University
Introduction
Goal
Generally, we often see many clocks in many markets. We see the phenomena of high speed rotation. Thus, we think up a concept of POV. We use it to design a circuit which is made up of LEDs, Bluetooth adapter, hall effect sensor, etc. Through them, we can use code to control the shining time of LEDs, thus, we can observe that it is like a clock.
We have two goals which we have to meet. First, we want to observe the phenomena of POV through the high rotation speed of the fan. Second, according to this concept, we can make a different clock.
Bluetooth Adapter
Extra Object for Balance
Persistence of Vision It’s a kind of phenomenon caused by the speed of the reaction of the Optic nerve. The scenes maintain approximately 1/16 seconds. Previously, we have seen many kinds of the electronic scroll. They used this technique to make a dynamic sentence and deliver some messages. We tried to make a device like the electric scroll. Differently, we only use a line of LEDs attached on the fan to display a scene of clock.
Arduino Pro Mini
Switch LEDs
U18 Hall Effect Sensor Our Design of Clock
Fan
Hall Effect Sensor and Hall Effect It is a device which is used to detect the rotation speed. How does it work? When the magnet gets close to it, , it works as a short circuit, so it can
be used like a switch. We plan to fix a magnet on the frame of the fan, thus, we can find the rotation speed of the device. Then, what is the hall effect? When the current passes through a magnet field which is perpendicular to it, the charged particle will experience Lorentz force which is a vector and it will perpendicular to the current and the magnet field. Lorentz force: 𝐹 = 𝑞(𝐸 + 𝑉 × 𝐵).
3 min
Our Clock of Fan in Dark Flow chart of the program
Bluetooth Adapter HC-05 This device can communicate with the computer by the Bluetooth. With this device, we can input the program to the Arduino pro mini anytime. Moreover, we can transport some message (ex. the resent time) to the Arduino.
Hall Effect 6
Adjust the resent time and the rotation speed Start
Judge if the output of the hall effect sensor is zero
Voltage (V)
5 4 3 2
Arduino Pro Mini
1 0 2796
2896
t (ms)
2996
3006
Time evaluation signal of Hall IC
Bluetooth Adapter
Conclusion • We set the displaying frequency of POV display after the measurement of fan rotating speed from Hall sensor. • According to the concept of POV, we successfully used Arduino card to set the shining time of LED array, and display the hour hand, minute hand, and the number labels on the clock face. Refreshment of each frame is triggered by the Hall effect sensor.
Judge the resent time
Display the numbers and the points
Display the hour hand and the minute hand
Reference [1] https://www.arduino.cc/en/Main/arduinoBoardMini [2] https://sites.google.com/site/msp430launchpaddiy/kuo-chong-jie-mian/pov-onlaunchpad [3] https://www.youtube.com/watch?v=2hASOre63Nk [4] http://www.instructables.com/id/Bluetooth-Serial-Adapter-for-Pro-Mini/
