As we had simulated the circuit we are going to use in the experiment in the first lab, this week, we are going to do something on the breadboard to build our actual circuit.
According to the supervisor's suggestion, we were supposed to divide the circuit into different parts which have different functions, so, our strategy is that, building the circuit firstly and test different parts of it step by step.
Before building the circuit, we firstly tested the PIR sensor according to its specification sheet and we build a simple amplification circuit to test the function of LM358 operational amplifier, according to the table below, again it proves the importance of the amplification circuit, without it, the response of the PIR sensor is too tiny to be detected. After mastering how to connect and drive them, we started to build the circuit.
Source Voltage when no
heat movement in front of sensor (V)
|
Source Voltage when
heat movement in front of sensor (V)
|
0.79
|
0.72
|
As can be seen in figure 1, we built the complete circuit and checked it carefully to ensure there is no mistakes in the connection.
After building the circuit, we started to test it step by step, first of all, we tested the first amplification circuit, with a sine wave signal as input, however, the output is not as our expectation, we tried to do some modifications to our circuit for several times but still, no satisfying result.
The procedures above took us an entire day, and obviously, we have already been after our schedule, we have to speed up and find out the problems in next week's lab time.
Our strategy is to build the circuit step by step again and this time, we will pay specific attention to the connection of LM 358, the value of resistors and capacitors to make sure all these elements are correct. Hopefully we can finish the circuit in the morning section of next lab and we can do some more tests in the afternoon, for example sensing angel, sensing distance, response time.
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