Week 3 - Testing

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 distinct. Hence, the output of the second stage can be connected with a LED which means if the PIR detects some actions, then the state of the LED will be changed such as from lighting to darkening.

Then, in the real test, when our tester passed in front of the PIR, then the output displayed on the oscilloscope was as shown in figure 3 and video:

Figure 3

Test 3

The third stage

The third stage is a comparator so that the output is a square wave, and the result is shown in figure 4.

Figure 4

Figure 5

As shown in figure 4 and figure 5, the output is quite clear rectangular wave which is much readable on the screen.

In summary, during this week experiment,  the circuit was finished and we did the most of test,  the result that is similar to simulation. However, the circuit was not perfection and we need to check the circuit is stable or not. While, in the next week, the whole work will be done and we will do the experiment again.