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Subject: Self-Introduction

Dear Professor Blackstone,

I am writing to introduce myself as a student in your Effective Communication class. Having graduated from diploma in environmental science in Republic Polytechnic, I am keen on furthering my studies in a local university due to the huge emphasis and importance placed on educational qualifications in this modern world. As education and learning are vital in our life, I feel the urge and drive to enhance my level of competencies. I am interested in studying Sustainable Infrastructure Engineering (Building Services) offered in Singapore Institute of Technology after my polytechnic education as I’d like to experience an entirely different lifestyle of being an engineer.

Having interned in the department of biological sciences in National University of Singapore during my year 3 Industry Immersion Programme (IIP) in polytechnic, I’d definitely understood the importance of effective communication where I’d to present my findings of certain plant species that were tasked to me to a group of professional researchers. This was when I’d experienced and understood that presentations and written communications are inevitable and of utmost importance for wherever I go.

As my polytechnic puts a bigger emphasis on presentations as compared to other polytechnics, I am proud to be more confident and adept in holding a better presentation to a group of audiences. However, though I can definitely say that I’d improved on verbal communications, I still believe that my feelings of stage fright are still present.

Hence, I hope to enhance my effective communication skills that hold greater emphasis on better contextual presentations of findings and delivering of message to the intended audiences. Additionally, I hope to improve my confidence in presentations so that I’d know exactly how to control my stage fright and present myself as a more confident speaker.

I look forward to your teachings and guidance in class.

Yours Sincerely,
Wong Jun Peng
SIE2017 Group 5

 

Edited on 11 Sep, 11:30pm

Edited on 23 Sep, 1:22pm

Edited on 24 Sep, 9:21pm

Edited on 27 Sep, 12:36pm

Blogs read and commented:

Joel, Hong Yu, James (Group 5), Shu Han (Group 1)

 

 

 

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Transmittal Letter of Technical Report (Refined)

Team Conservo

SIE2016 Effective Communication Group 5

Singapore Institute of Technology

10 Dover Drive

Singapore 138682

 

17 November 2017

 

Ms Wendy Gwee

Estates Division

Singapore Institute of Technology

10 Dover Drive

Singapore 138682

 

Dear Ms Gwee,

 

In response to the Estates Division of Singapore Institute of Technology (SIT), we submit herewith a proposal to recommend the installation of passive infrared (PIR) motion sensors to reduce electricity consumption and promote energy conservation in SIT@Dover.

This proposal has been developed in light of a problem with constant wastage of electricity in the campus compound as the lights in classrooms are not switched off after usage. Our team’s intention is to offer a viable solution to the electricity wastage by integrating PIR motion sensors into our work environment.

The report comprises of a review of the identified problem, the comparison between different types of possible sensors and the reasons for choosing PIR sensors over other types. As students in SIT, we realize the importance of cutting down electricity consumption to move towards sustainability in the future.

We would like to express our gratitude to you for taking the time to read through our proposal. Your consideration for our recommendation to integrate an automated light control system into the school compound is greatly appreciated.

 

Yours sincerely,

Team Conservo Representative:

Khoo Nee Kong

Ong Jian Chen

Wong Jun Peng

Phua Chi Kin Keric

 

Enclosures: Proposal

Technical Report on Proposed Solution (Refined)

5  Proposed Solution

With the existing situation of classroom energy wastage in SIT@Dover, the team proposes the use of motion sensors to automatically control the lights in classrooms.

 

5.1  Using Motion Sensors in Classrooms

The proposed solution would be to install motion sensors, fitted with a timer device, in classrooms so as to regulate the use of lights. The process for installing the sensors is simple : only a re-routing of electrical wiring is needed. This will connect the sensor to the main electrical circuit that leads to the lightings. With that, the sensor will automatically turn the lights on whenever someone walks into a classroom (CircuitDigest, n.d.). Subsequently, the timer device will countdown for 15 minutes before turning the lights off in a vacant classroom.

 

5.2  Types of Motion Sensors

Research has identified three types of motion sensors, with each utilizing different forms of radiation. The advantages and disadvantages of each sensor are listed down (Agarwal, n.d.).

 

5.2.1  Passive Infrared (PIR) sensor

The PIR motion sensor uses a pyroelectric sensor to detect infrared (IR) radiation emitted by the human body. The IR radiation received by the sensor excites the electrons in the sensor’s substrate, creating an electric signal which is then amplified into a larger signal for processing. This processed signal can then be used to control classroom lights. The sensor detects a wavelength range of 8 to 12 micrometers, which corresponds to the IR radiation emitted by the human skin (33 to 38°C). It scans for rapid changes of IR energy in an environment, thus only detecting motion (HowStuffWorks, n.d.).

 

Table 1.    Pros and cons of PIR sensors

Pros Cons
1) Economical and long-lasting 1) Unwanted shutoff
2) Cannot penetrate glass doors, windows and concrete walls. 2) Cannot detect differences between humans and animals with similar temperature range.
3) Self-powered

 

5.2.2  Microwave sensor

The microwave sensor generates microwave pulses into an area and detects any phase shifts in the receiving signal as the waves bounce off objects (safewise, n.d.). It is an active sensor (constantly generating microwaves into its environment).

 

Table 2.    Pros and Cons of Microwave sensor

Pros Cons
1) Very sensitive 1) Expensive
2) Works in harsh environment 2) Requires external power source
3) Able to penetrate through walls

 

5.2.3  Combined types of motion sensors

These dual sensors are activated when both microwave and infrared detect motion. For instance, a dual sensor will start out on the passive infrared setting, consuming less energy. When the passive infrared sensor is tripped, the microwave sensor will turn on (Elprocus, n.d.).

 

Table 3.    Pros and Cons of dual sensor

Pros Cons
1) Extremely sensitive 1) More expensive compared to other types of sensors.
2) Resistant to outdoor exposures and other interferences

 

Edited on 2nd Dec, 12:52am

Edited on 2nd Dec, 2:19am

Reader Response Draft 4 (Improved)

In the article “Use of Cladding in Buildings Here Have Grown in Recent Times”, Faris Mokhtar (2017) reported that cladding is likely to pose fire hazards to buildings despite benefits of usage. According to Budig (as cited from Mokhtar), though cladding is largely used for providing heat insulation to buildings, safety can be a concern. Fire can spread quickly due to ventilation gap between claddings and building walls. As such, Singapore Civil Defence Force (SCDF), as stated from Mokhtar, requires that the materials used for claddings in buildings must comply with the Singapore Fire Code to ensure that fire will not be extended to other areas should the material be ignited. Based on the SCDF regulations, all buildings must conform to the requirement for the use of claddings as stated in the fire code. Fire safety certification of the buildings also has to be provided by the professionals on a yearly basis.

 

Though the use of claddings may cause fire hazards, it is certain that with proper fire safety actions being carried out, safety will not be compromised.

 

One safety action that has been carried out by SCDF is through the conducting of assessments to ensure that buildings conform to the Singapore Fire Code. The fire code states that it only accepts non-combustible panels or class “0” panels being used on external walls that do not allow the spreading of fire. However, most buildings that have been tested do not conform to the standard as stated by SCDF. Based on the article “Cladding for 36 buildings may pose fire risk” (2017), 36 buildings out of a total of 41 buildings do not conform to the standard. With this being said, SCDF is cooperating with building owners to ensure that unacceptable panels will be removed within 2 months. This is done to assure the occupants that the buildings are safe for usage through the assessment being carried out.

 

Secondly, SCDF has filed a police report to determine the source of the composite panels used for claddings. Through the investigations, it has been found that two models of composite panels FRB1 and FRB2 were mixed and supplied to buildings for use as claddings. This should not be the case as FRB1 and FRB2 are meant to be used separately in different parts of the buildings. According to the article “SCDF Takes Immediate Actions to Ensure Fire Safety of Buildings,” (2017) FRB1 is certified as class “0” for cladding usage in buildings and FRB2 is certified as class “1” usage for roofs and internal walls. However, FRB2, which is a class “1” type material, has been found to be used in claddings for buildings. Furthermore, the article also stated, “The stocks of Alubond model FRB1 were also not uniformly of the required standard.” This would mean that even FRB1 which is supposed to be of class “0” requirement did not conform to the standard. As a result, actions will be taken on building owners if non-Class “0” panels are found to be used as claddings based on the investigations.

 

Lastly, SCDF has taken actions on affected buildings that have non-Class “0” panels used for claddings. This is done through the testing of buildings by certification bodies. Based on SCDF’s webpage, the list of affected buildings with the cladding removal status is displayed for different buildings in Singapore. This means that claddings that do not fulfil the requirement of the class “0” standard have to be removed within 2 months. If building owners are not able to achieve this goal within the stipulated deadline, their certificates of conformity will be removed. As such, SCDF makes sure that buildings that do not conform to the Singapore Fire Code have their claddings removed so as to receive the certificate of conformity with 5 years validity.

 

Although it is certain that the use of claddings in buildings has the tendency to pose fire risk, it is clear that proper actions have been carried out by SCDF to ensure that safety will not be compromised for the building occupants.

 

References

Leong, W. K. (2017, September 07). Buildings stepping up fire safety precautions after failing cladding tests. Channel NewsAsia. Retrieved from http://www.channelnewsasia.com/news/singapore/buildings-stepping-up-fire-safety-precautions-after-failing-9191350

Mokhtar, F. (2017, June 17). Use of cladding in buildings here have grown in recent times: Experts. Today Online. Retrieved from http://www.todayonline.com/singapore/use-cladding-buildings-here-have-grown-recent-times-experts

Mokhtar, F. (2017, August 24). Claddings for 36 buildings may pose fire risk. Today Online. Retrieved from http://www.todayonline.com/singapore/police-investigating-unapproved-cladding-40-buildings-singapore

Singapore Civil Defence Force. (2017). SCDF takes immediate actions to ensure fire safety of buildings. Retrieved, August 24, 2017, from https://www.scdf.gov.sg/general/news/news-releases/2017/scdf-takes-immediate-actions-ensure-fire-safety-buidlings

Singapore Civil Defence Force. (2017). Fire safety of buildings (with cladding). Retrieved from https://www.scdf.gov.sg/fire-safety-buildings-improper-use-cladding

Critical Reflection Draft 2 (Final)

At the beginning of the trimester, I’ve set some goals for myself. I’d like to enhance my ability to deliver messages effectively to the audience whenever I present and also improve my confidence in presentations so as to know how to control my stage fright. Those are the 2 long-term goals that I’ll like to achieve throughout my life as a confident speaker. I’ve been proud to notice my improvement for both of the 2 goals mentioned in my actual presentation where I was able to achieve the 2 set objectives for myself. This was accomplished through a number of rehearsals within my own team as well as getting constructive feedbacks from the team members regarding how I can improve on my own presentation. However, I’ve also realised certain mistakes that I was making during the presentation itself. As such, to ensure continual learning, I’ll always do rehearsals for formal presentations again in the future and continue to gather feedbacks from the audience so as to improve my public speaking skills.

Throughout our project in motion sensor, I’ve realised that teamwork is extremely important. Every team member has their own strengths and weaknesses. Some of us are better in doing the script typing, some have more ideas in the report that can provide the team numerous options to select from our report topic. Thus, it’s necessary to split up the work between team members who specialise more in their own areas to effectively contribute to the learning outcomes. However, after working with my team in the report, I’ve realised that our team did not know what areas we could improve on from each section of the report while working on it. We mainly waited till the end of the report for consultation. Thus, one area of improvement will be to consult the professor more frequently while working on the report.

 

Edited on 1st Dec, 1am

Edited on 1st Dec, 2:30am

Edited on 1st Dec, 10:48pm

Blogs read and commented:

Yong Quan, Claudia, Jerome Teng (Group 5)

Critical Reflection Draft 1

At the beginning of the trimester, I’ve set some goals for myself. I’d like to enhance my ability to deliver messages effectively to the audience whenever I present. This is a long term goal set to ensure that whenever I present or communicate with people, messages can be delivered effectively to them. Besides effective communication, I’ve also set another goal which is to improve my confidence in presentations so as to know how to control my stage fright. This has been another long term goal that I’ll like to achieve throughout my life as a confident speaker. I’ve been proud to notice my improvement for both of the 2 goals mentioned in my oral presentation where I was able to achieve the 2 set objectives for myself. However, to ensure continual learning, I’ll always look for ways to improve myself for whichever areas that I may be lacking in.

Throughout our project in motion sensor, I’ve realised that teamwork is extremely important. Every team member has their own strengths and weaknesses. Some of us are better in doing the script typing, some have more ideas in the report that can provide the team numerous options to select from our report topic. Thus, it’s necessary to split up the work between team members who specialise more in their own areas to effectively contribute to the learning outcomes. However, after working with my team in the report, I’ve realised that our team did not know what areas we can improve on from each section of the report while working on it. Thus, one area of improvement will be to consult the professor more frequently while working on the report.

 

Analytical Reflection

In all honesty, I believe that I did pretty well for my actual presentation where I was able to present confidently and fluently to the audience. I was able to make use of hand gestures and smiled frequently throughout the presentation with detailed explanations for my part. However, during the actual presentation, I stood in front of the presentation slides. Initially I didn’t realise that I was partially blocking the classmates’ view of the slides. I thought that by standing in the middle of the slides I can display myself as a more confident speaker. To me, public speaking is all about displaying confidence and public engagement. Although content knowledge is important as well, I feel that it’s more important for the audience to be engrossed and appreciate what you’re presenting rather than to view the slides. Everyone will be able to view the slides on their own. The focus here is more about the speaker himself delivering a good presentation to the audience. Having being in a polytechnic which specialises more on public speaking, I feel that this is the part that I’ve neglected. Confidence and public engagement are essential, but to perfect the presentations, it’s important that the presenter choose a spot to stand so as to reduce obstructions to the audience.

Furthermore, I believe that teamwork is equally important in our presentation where the team needs to know how to effectively transit the slides to the next presenter. Teamwork includes helping our team members during the actual presentation by answering questions that the audience has asked. I did softly answer Keric’s questions about certain mathematical calculations to help him out when he was trying to answer Jerome’s question. However, I feel that I can work on taking the initiative to answer more of the classmates’ questions if needed.

 

Edited on 1st Dec, 12:57am

Edited on 1st Dec, 1:57am

Edited on 1st Dec, 9:18pm

Blogs read and commented:

Nee Kong, Hong Yu, Jerome Tay (Group 5)

Technical Report Draft 3

1  Introduction

Energy conservation in Singapore has been on the rise in recent years. As an open economy with no natural resources, Singapore is vulnerable to rising energy costs that can affect our economic competitiveness. It is crucial that we take steps towards becoming more energy efficient.

In the Dover campus of Singapore Institute of Technology (SIT@Dover), there is a tendency for students to leave the classrooms without switching off the lights. Students have indicated that there might be another class going on later, requiring no necessity to switch them off. In a rush for the next class, students might forget to switch the lights off. Moreover, there are some students who do not even bother about energy conservation (Appendix A).

With students developing such energy-wasting behavior, security guards have to switch off the lights in every classroom after office hours. As a result, unnecessary costs on manpower and finances are incurred. Hence, there is a need for motion sensing device that could automatically switch off the lights in classrooms.

It was observed that the air-conditioning in SIT@Dover was primarily relying on chiller units. These chiller units function by supplying cool water throughout the building, with fans to blow the air, cooled by the water, out into the classrooms. This system is operated via SIT@Dover’s main controls. For this reason, the team has decided, after much deliberation, to focus on lights only, since the lights are controlled manually in individual classrooms.

2  Problem Statement

Too frequently at SIT@Dover, students do not turn off the lights in classrooms after using them, which results in energy wastage and an increase in utilities expenses. Unless motion sensor devices are installed in these classrooms, the institute will continue to bear unnecessary costs that could be directed to more productive avenues.

3  Purpose Statement

The aim of this report is to recommend the estates division of SIT@Dover to install an automated control system in classrooms. By implementing this system, the university will be able to reduce energy consumption and utilities bills expenses.

4  Current Implementation

Based on the team’s observations,  there is currently no automated system in place to switch off lights in vacant classrooms (see Appendix B). Although there are areas in the school that are fitted with motion sensors, classrooms are not included. Only standard light switches are installed in these classrooms, requiring users to manually turn off the lights.

The team has also observed 34 classrooms (see Appendix C) in SIT@Dover from 6pm to 10pm throughout the period from 23 October 2017 to 27 October 2017. The number of classrooms whose lights were turned on until 10pm was half the total number observed. Additionally, it was observed that security guards accessed these classrooms and turned the lights off at 10pm. With these observations, the team determined the current implementations for energy conservation were as such, which were counter-effective.

5  Proposed Solution

With the existing implementation in SIT@Dover, the team proposes the use of motion sensors to automatically control the lights in classrooms.

 

5.1  Using Motion Sensors in Classrooms

The proposed solution would be to install motion sensors, fitted with a timer device, in classrooms so as to regulate the use of lights. The process for installing the sensors is simple – only a re-routing of electrical wiring is needed. This will connect the sensor to the main electrical circuit that leads to the lightings. With that, the sensor will automatically turn the lights on whenever someone walks into a classroom. Subsequently, the timer device will countdown for 15 minutes before turning the lights off in a vacant classroom.

 

5.2  Types of Motion Sensors

Research has identified three types of motion sensors, with each utilizing different forms of radiation. The advantages and disadvantages of each sensor are listed down.

 

5.2.1  Passive Infrared (PIR) sensor

The PIR motion sensor uses a pyroelectric sensor to detect infrared (IR) radiation emitted by the human body. The IR radiation received by the sensor excites the electrons in the sensor’s substrate, creating an electric signal which is then amplified into a larger signal for processing. This processed signal can then be used to control classroom lights. The sensor detects a wavelength range of 8 to 12 micrometers, which corresponds to the IR radiation emitted by the human skin (33 to 38°C). It scans for rapid changes of IR energy in an environment, thus only detecting motion.

Figure 1.    Passive Infrared Sensor

 

Table 1.    Pros and cons of PIR sensors

Pros Cons
1) Economical and long-lasting 1) Unwanted shutoff
2) Cannot penetrate glass doors, windows and concrete walls. 2) Cannot detect differences between humans and animals with similar temperature range.
3) Self-powered

 

5.2.2  Microwave sensor

The microwave sensor generates microwave pulses into an area and detects any phase shifts in the receiving signal as the waves bounce off objects. It is an active sensor (constantly generating microwaves into its environment).

Figure 2.         Microwave sensor

Table 2.    Pros and Cons of Microwave sensor

Pros Cons
1) Very sensitive 1) Expensive
2) Works in harsh environment 2) Requires external power source
3) Able to penetrate through walls

 

5.2.3  Combined types of motion sensors

These dual sensors are activated when both microwave and infrared detect motion. For instance, a dual sensor will start out on the passive infrared setting, consuming less energy. When the passive infrared sensor is tripped, the microwave sensor will turn on,.

Figure 3.    Combined types of Motion Sensors

 

Table 3.    Pros and Cons of dual sensor

Pros Cons
1) Extremely sensitive 1) More expensive compared to other types of sensors.
2) Resistant to outdoor exposures and other interferences

5.3  Benefits of Proposed Solution

The benefits have been projected by first, choosing the type of sensor, and then assessing its benefits in classrooms.

5.3.1  Choosing the Type of Sensor

After looking into the different types of sensors from the team’s research, the PIR sensor is the most suitable sensor for classrooms. The three main reasons are as follows:

  1. The PIR sensor is the cheapest type of motion sensors. Since SIT@Dover will be used for the next 3 to 5 years before moving to Punggol, it is best to use the cheapest type to fulfill basic motion sensing capabilities.
  2. The PIR sensor does not require any additional power source to function. It basically ‘waits’ for IR radiation to be absorbed by its pyroelectric sensor.
  3. The PIR sensor cannot detect through glass doors, windows or concrete walls. Hence it will only detect if someone walks into a classroom and not walking past a classroom.

5.3.2  PIR Motion Sensor in Classrooms

Having a PIR motion sensor installed in the classrooms of SIT@Dover allows for better regulation of lights. Whenever the classroom is vacant for 15 minutes, the lighting units will be switched off. This will help in saving electricity and reduction of utilities bills, allowing the institute to be more productive in other avenues where required.

5.4  Evaluation of Proposed Solution

Evaluation involves the installation of the PIR motion sensor in classrooms only. For that, the team has come up with a few projected challenges that SIT@Dover and its students would face.

5.4.1  Cost of Rewiring the Main Electric Circuit

Although PIR sensors are very cheap, the cost of hiring professional electricians to perform the rewiring works is expensive, considering a large number of classrooms. However, the costs can be earned back from the savings incurred over the years of saving electricity by cutting unnecessary wastages.

5.4.2  Disruption of Classes

Electrical works may disrupt certain classes from having their lessons in the particular classrooms where the works may be done. In order to mitigate this, the electrical works may be done either on weekends or after office hours, where there are very few, if not zero, classes going on. Another possible solution is to liaise with the administrative division on the schedule of classes.

5.4.3  Unexpected and Unwanted Switch Off

As supported by the team’s survey, students have opined that the lighting units may switch off in the midst of classes, where there is minimal movement. This may be true only when there are very few students in a classroom. When a classroom is packed with more students, there is a larger tendency for movement to occur within a span of 15 minutes, triggering the motion sensor to keep the lights turned on.

5.4.4  Classrooms Used as Sleeping Areas During Camps

During student orientation camps, classrooms are used as sleeping areas for campers and also act as important rooms (i.e. operations room, logistics room) for the camp committee members. For this reason, lights should remain turned off even if there is movement in the room to prevent campers from waking up due to sudden light exposure. In order for this to happen, a master switch can be fitted into the main electrical circuit as well for each individual classrooms, as shown in Figure 4. This will help deactivate the motion sensor and control the lighting units in accordance with what the user wants. This feature should only be used in such special circumstances, but not on ordinary days.

Figure 4.    Circuit diagram of a master switch with PIR sensor (adapted from: CircuitDigest.com)

6  Methodology

This report follows wholly on the information and research gathered using the following methods:

6.1  Obtaining Photographic Evidence in SIT@Dover

Our team, on random days, stayed in school up to 9pm to investigate the different areas of the school, mainly the University Services Centre and Academic Plaza. We then took pictures of the classrooms where lighting units were left turned on. These classrooms would be the places where the PIR motion sensors are installed.

6.2  Identification of Students’ Opinions

A survey was conducted by our team on students’ habits (if they turn off the lights), and their feedback on having motion sensors in classrooms to control the lights was taken into account. The results were then analyzed and used to support the notion that motion sensors in classrooms would help the institute to cut utilities costs.

6.3 Product Selection Through Online Research

In order to recommend solutions for the institute, the team performed online researches on the most suitable product. Each product was carefully evaluated through a number of considerations and conditions identified by the team, and chosen as the ideal product for the proposed solution.

7  Conclusion

The proposed solution to energy conservation in SIT@Dover involves installing an automated motion sensor system where PIR sensors can control the utilities of classrooms. This would significantly reduce the institute’s electricity consumption. Although there are limitations to such a system, they are either temporary or easily overcome. Also, the advantages outweigh the limitations in the long term. In retrospect to the institute’s shift to the new Punggol campus, the stipulated date shifting remains unfixed. Thus, it is critical for the institute to minimise energy consumption as much as they can. Therefore, the proposed solution would definitely aid SIT@Dover in advancing toward a more technological and greener environment, where cost-saving and energy conservation serves as an ideal situation for both the environment and the institute.

8  References

Agarwal, T. (n.d.). What are motion sensors and how do they work. Elprocus. Retrieved from: https://www.elprocus.com/working-of-different-types-of-motion-sensors/

 

Aggarwal, N. (2017). Exposing students to clean energy technologies and practices. Business Times. Retrieved from: http://www.businesstimes.com.sg/hub/energy-efficiency-national-partnership/exposing-students-to-clean-energy-technologies-and

 

Aggarwal, N. (2017). Ministry of Finance leading the way in energy-efficiency practices. Business Times. Retrieved from: http://www.businesstimes.com.sg/hub/energy-efficiency-national-partnership/ministry-of-finance-leading-the-way-in-energy-efficiency

 

CircuitDigest. (n.d.). PIR Sensor Based Motion Detector/Sensor Ciruit. CircuitDigest.com. Retrieved from: https://circuitdigest.com/electronic-circuits/pir-sensor-based-motion-detector-sensor-circuit

 

HowStuffWorks. (n.d.). How do motion sensing lights and burglar alarms work? HowStuffWorks.com. Retrieved from: https://home.howstuffworks.com/home-improvement/household-safety/security/question238.htm

 

Johnson, S. (2017). Advantages and disadvantages of infrared detectors. Sciencing.com. Retrieved from: https://sciencing.com/advantages-disadvantages-infrared-detectors-6151444.html

 

Safewise.com. (n.d.). The Beginner’s Guide to Motion Sensor. Safewise.com. Retrieved from: https://www.safewise.com/resources/motion-sensor-guide

Tech.faq. (2016). PIR Sensor. Tech.faq.com. Retrieved from: http://www.tech-faq.com/pir-sensor.html

 

Edited on 30th Nov, 1:22pm