Y2 Project Week 2
Members:
Qinglie Zhu, Zheng Zhao, Junhao Zhu, Zhiyuan Zhang
General Ideas:
As mentioned last week, our group aims at considering a alternative proposal of build the sound monitoring system. It should be noticed that the whole design is based on the micro controller named Arduino Uno. Apart from that, we make attempt to test the Bluetooth function by Arduino.
Component:
1. Arduino Uno
2. Microphone
3. Chip LM386
4. Chip AD536
5. LM331AN
6. Bluetooth Model
Description of Components:
1. Microphone
It is used to detect the voice signal in a specified circuit, applied of which is able to detect signal without filter.
2. Chip LM386
The chip LM386 is applied to an amplifier circuit which can amplify the voice signal.
3. Chip AD536
The chip AD536 is an A/D converter that can convert the signal from AC to DC.
4. Chip LM331AN
The chip LM331AN is able to convert the frequency of voltage. Moreover, it can be converted from analogue to digital.
5. Bluetooth Model
The model is used to transfer the detecting result from the sound monitoring system to the smartphone.
Experience of the experiment:
1. New Schematic
After considering the circuit, the group succeeds in building the new circuit of sound monitoring, which can be divided into 3 parts: amplifier circuit, AC to DC signal circuit, A/D converter. The circuit is shown below.
Figure 1. The New Schematic of Sound Monitoring System
2. Connect and Test The Circuit
The experience of connecting is a relatively tough part in the week. It should be emphasized that we only constructed the amplifier circuit which is the first part of sound monitoring system due to several difficulties. The result is shown below.
Figure 2. The Circuit of Amplifier
The first tough part is that the chip LM386 is not connected to the middle part of the breadboard, which results in the failure of transferring signal. The output of amplifier circuit is just a straight line rather than the original waveform with larger amplitude.
After connecting the correct circuit, we have the second hard part since we made a wrong decision. We insert a sinewave whose mean amplitude is 113 mV. The figure is shown below. It should be emphasized that there are 2 wrong things here. The first one is that the input signal is too large so that the output signal is too larger for oscilloscope to display. Furthermore, the gain is too large which results in large output as well. The output is a strange one as shown below. The output is like a clamper circuit.
Figure 3. The Wrong Input Signal
Figure 4. The Wrong Output Signal
After that, we input a relatively small signal and adjust the gain by resistor. The smaller input signal is shown below. Then, we obtain the correct output as shown below. It should be emphasized that the gain is around 20.
Figure 5. The Smaller Input Signal
Figure 6. The Output With Gain of 20
Finally, we failed to transfer the signal from circuit to smartphone via the Bluetooth. The reason why we fail is that the smartphone cannot convey and receive the instruction.
Conclusion:
We succeeded in constructing the first part of the sound monitoring system which is amplifier circuit, but failed in transfer signal via Bluetooth. In the next week, we will build the entire circuit of sound monitoring system involved in Arduino Uno. Moreover, we will test the whole circuit with Arduino as well.
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