sequential (66) RJ45 (Protocol) direction of current flow

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Me: Ok.
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John : See the Picture above.  We use Rd+ and Rd- to create a Clk line. 
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Me: Ok.
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John : Now, b1 send a signal to the + side of the operational amplifier. 
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Me: How many voltage is this signal ?
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John : 4.5 V.
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Me: Ok.
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John : In fact, only Tx+ is induced 4.5 V. Tx- is  only induced 0.5 V. Why ? Because,  the current direction of Tx- isn't clear yet.
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Me: Common mode block the direction of the current flow of (Tx -).
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John : Yes, however,  during the next round, the direction of current flow will be changed.  
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Me: Yes, by then, Tx- will be in a favorable situation.  
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John: Something like the below,
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If (electrical current = left)
{
TX+ = favorable 
TX- = unfavorable (the direction of current flow is not yet clear.)
}
else 
{
TX+ = unfavorable (the current flow is not yet clear)
TX- = favorable 
}

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