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Audio playback system using Infrared light for motion detection

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Why Audio playback system?


Every time I will go to Ayala Center Cebu to stroll or just to buy groceries I will always encounter this automated sliding glass door at the inner part of the mall between Terikayi Restaurant and Yellow Cab, the sliding glass door automatically open smoothly and with ease. While passing on this glass door, an idea popped out of my mind “What is the sole purpose of the technology? Was it for businessmen to increase their profits or for better living and convenience of humankind?”

I do understand why Mall owners always try their best to improve their establishments for customers to appreciate and like the environment they are momentarily staying with. Then I just make an ironic statement for technology, I asked myself “What does really matter at the end of the day is it MONEY or CONVENIENCE?” Well this will take a very long argument if I continue this one. But surely it will always depend on the type of person you are dealing with. Honestly all this thoughts already came out in my mind after pass the glass door. I really don’t know why and I can’t express the feeling, maybe I’m just wonder-struck by that time. On going home, I rode in the jeepney, looking at other people who are hiring a taxi to go to some places they want to, and it is very convenient to ride on a cab but it really cost a lot in compare into riding a jeepney. Then I conclude that TECHNOLOGY cost MONEY but yield CONVENIENCE.

As I lay down in my bed a thought came out into my mind that maybe I could add a little bit of technology to that automated sliding glass door “Something like a machine that will automatically address greetings or cautions and warnings, and reminders to every customers passing through”. Then I decided that this will be my project an Audio Playback system that will use infrared light to detect motions for every customers passing through that automated sliding glass door. These way employers may not hire anymore employees to “greet” or “address reminders” to every customer in the mall, thus lessen their expenses for the employee’s salary (but that doesn’t mean electricity will do so). 

How does it work?


First, I used the device called Infrared motion detector. The infrared motion detector can be used to sense intrusions. Infrared rays reflected from a static object will be in one phase, and the rays reflected from a moving object will be in another phase. The circuit uses this principle to sense the motion. The IC1 (NE 555) is wired as an astable multivibrator. As we all know, astable multivibrator will switch between its two unstable states, both the reset and set states. Then, the IR diode connected at the output of this IC (NE 555) produces infrared beams of frequency 5Khz. This beam will be picked up by the photo transistor Q1. At normal condition, when there is no intrusion the output pin (7) of IC2 will be low. When there is an intrusion the phase of the reflected waveforms has a difference in phase and this phase difference will be picked by the IC2.Now the pin 7 of the IC 2 goes high to indicate the intrusion. An audioplayback system is connected at the output of the IC to indicate the intrusion.

Problem encountered:

During the connections in the IC, some were short circuited so the audioplayback output did not work.

Solution:
When drilling holes, the footprint must be large enough so that it will be easy in attaching the components into the PCB.

SCHEMATIC / LAYOUT / ACTUAL CIRCUIT:
  • IR TRANSMITTER
  • IR Receiver and Playback
Actual Circuit

I used the program Orcad in making the circuit diagram and in making the Printed Circuit Board. There are lots of program to use aside from Orcad.

About the author

Paul Ryan A. Dedumo is a blogger and an Electronics and Communication Engineering student at University of San Carlos. Learn and inspire as you follow him in his links, blog and other social media accounts.

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