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Week 5 - Testing the Whole System

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In week 5, the project has almost finished. So the main task of this week is to testing the system more times and to find the existing mistakes. It should be noted that the poster is already done, which can be seen in Figure 1. Figure 1: The Poster During the testing, the detecting distance of PIR was set from 1 to 3 meters. When a tester was passing by the circuit, the sensors would react and LED screen will show the figures. When another tester who is thinner passing by will cause different results. Here are the pictures showing the process of the testing and the consequent waveform from oscilloscope. Figure 2: 100cm Figure 3：150cm Figure 4: 200cm Figure 5: 250cm Figure 6: 300cm In addition, our group have built three identical circuits to test the movements of people falling down. The basic theory is that when people fall down, only the sensor at the bottom will receive the signal. At the same time, when a person walks through the system...
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Week 4 - Improvement and Recording

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In the previous three weeks, there two circuits which have been completed. Because the circuit is too complicated and there must be some tiny mistakes in the circuit on the breadboard, the sensor cannot detect the motions sensitively and the waveforms on oscilloscope are full of noise. Therefore, what was concerned on this week was to do some improvement of the circuits and then make a testing plan to record the data. It can be observed that if the tester is a little far from the sensor, there would be a very slight change on the output signal. In other words, the testing distance of the sensor is too short. In order to solve this problem, a lens was used to put over the sensor. The lens is able to centralize the light so that it can detect the changes of light more easily. In this way, the detecting distance is increased effectively. It can be seen in Figure 1. Figure 1 What need to be focused on is how to connect these two circuits and make them work simultaneously to det...
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Week 3 - Testing

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Last two weeks, the simulation of circuit have already done. Therefore, this week the key of point is to construct the other circuit and finish several tests and record it. First step is to constructed the whole circuit, according to our design paper and the circuit we have built last week, the teamwork had been done where are shown as below. Figure 1 The next step after building the two circuits was to test the waveforms of each section in the circuit on the oscilloscope. Test 1 The First stage The reaction of the first stage operational amplifier is shown in the figure below, it can be seen that when a palm is swept above, there is a signal from its terminal, the output is too tiny to be used, and the reason is about the gain of this amplifier, which can be changed by the variable resistor. Figure 2 Test 2 The second stage The goal of the second stage in this circuit is to amplify the signal so that the transformation of the signal can be more dist...
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Week 2 - Building the Circuits

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I n the second week, based on the simulation results of the circuit in the first week and suggestions given by the supervisor, our group decided to divide the whole circuit into three different parts, each section have different functions and test them separately. Before building the whole circuit, we tested the PIR sensor with amplifier at first to check its working principle, then we began to build the first part of the circuit and the diagram of first part circuit is shown below: Figure 1 : The first part of the circuit As shown in Figure 1, the PIR sensor has three pins which connect to different components, pin 1 is the drain which is connected to the Vcc, and pin 3 is connected the ground. The source is pin 2 that used as output of PIR sensor. Between pin 2 and pin 3, there is a resistor of R2 which is 47KΩ that is used to change the current signal into voltage signal so that the amplifier will be able to amplify the signal. The capacitor and resistors were conne...
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Week 1 - Simulation

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This project aims at the infrared sensor as well as its application. The infrared sensors are designed for the disabled people or elderly people living alone to detect their falling downs without contacting and then alarm and make some noise to call others to help. There are a few tasks in this project including simulation, building the circuits and testing and etc. As for the week 1, the main task was to do the simulation. The working principle is the sensor can detect the changes of light and then produce the current signal, in addition, the circuit is able to transfer the current signal to voltage signal so that it can be amplified. Firstly, after doing some research on the internet, a theoretical circuit was obtained. And the future work would be based on the circuit. The circuit is shown below. Figure 1 The second part is to use the Multisim to simulate the circuit on computer. There was a problem that the RE200B cannot be simulated in the software. As a result, ...
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