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In this lesson, we will talk about the relevant circuits of the microphones of low-end models

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In the previous lessons, we talked about relatively new models,

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such as Redmi K50, Xiaomi 11 and Huawei P40

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Now let's take a look at the circuit of a slightly lower-end model.

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Is it more complicated or simpler?

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This is Changxiang 20 model

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It also has a main microphone, a secondary microphone

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Its power supply is MIC BIAS, BIAS is the bias voltage

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AU is Big Audio

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It is also a model of the MTK platform, and the large power supply includes a large audio

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Its internal big audio communicates withe the CPU, AUD_DAT is the data

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There are 3 groups of main input and slave output,

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and there are also 3 groups of main output and slave input

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It is the same as the Redmi K50, there is almost no difference

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Take a look at some other low-end models

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For example, this early Qualcomm machine

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Its microphone circuit also has a main microphone circuit and a secondary microphone circuit

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On the circuit of the microphone, its power supply is also BIAS,

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and it has positive and negative inputs of the signal

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Although this mobile phone uses a Qualcomm mainboard,

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it also contains a large audio frequency in the power supply

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This big audio communicates with the CPU, which uses a sending data and a receiving data called PDM

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It uses these two lines to transmit the sound signal processed by the large audio to the CPU

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CDC is referring to Big Audio here

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The framework of the main circuit of the microphone has about 5 models,

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some are high-end and some are low-end.

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I won't look for its line, it's relatively simple

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Then everyone must pay attention, for example, where to check the main microphone,

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you can start from J1901

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This is the connector on the mainboard, which is connected to the tail plug board through a cable

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The circuit diagram of the main microphone only describes this part on the mainboard, you can start looking here

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Find this seat, find the data positive and negative,

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find the code of the power supply, enter it into the search box to search,

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and see if it is connected to a large power supply

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There are also channels for communication between the large power supply and the CPU,

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and the channels for receiving and sending data that transmit sound signals

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That's all for this lesson