This is a question about the Ethernet communication switch circuit

Other Hardware Product Design
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This is a question about the Ethernet communication switch circuit.

fig
fig1093×1033 169 KB

This is a question about the Ethernet communication switch circuit.

hello. There is a project I want to make.

This is switching Ethernet communication.

I'm trying to make it using 'multiplexer'.

But a problem arose. There is no connection between the RJ-45 signal and the gnd of the 'multiplexer' chip.

The 'multiplexer' chip has an analog signal range of
-15VDC ~ 15VDC.

The potential (voltage, GND) between RJ-45 and the 'multiplexer' must be correct for the signal to be distributed through the 'multiplexer'. I am curious how I can make it have gnd.

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Why do you think Ethernet uses a ground? The signals are all bi-polar, meaning the switch between + and - to transmit data. No ground needed.

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double check your wiring connection between the RJ-45 connector and multiplexer.

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@Paul_KD7HB
@johnn002

We sincerely appreciate your interest.

If I were to write more about what I wanted to create,
I want to make an ‘ethernet hub switch’.

So, I'm trying to make it through 'multiplexer'.
(I am designing it based on my thoughts. This is not the correct answer.)

When trying to design a switch with a 'multiplexer', the analog voltage range that passes through the 'multiplexer' is -15VDC to 15VDC.

Therefore, if there is no correlation between the RJ-45's analog signal and the 'multiplexer' GND, the signal will not pass through.

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That is correct, all signals are differential, assuming you are using a twisted pair. They are further isolated with a transformer, many times built into the connector. Consequently there is no need for common ground as long as the common mode voltage typically stays below 1500V, the isolation specification of the transformers. This link may help: Ethernet Protection Methodology

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Thank you for answer.

In theory, I know what you're talking about.

If so, are there any elements or modules that enable switch operation and are insulated?

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You can get a switch for a few $$$ why not get one and take it apart. Try this link it will help you understand what you need. https://robots.net/internet-and-connectivity/wifi-and-ethernet/how-to-build-a-network-switch/

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