PoE recommendations for System Blue
#9
"I didn't find the load resistor did anything useful other than get warm and ensure that the PoE splitter started up if the system board was disconnected."

:-)  The reason for this resistor is to give the switch-mode power supply a resistive load.
In a switch-mode powersupply there are a resonant circuit. If this is loaded by an inductor with a high Q, it can interfere with the circuit and change the frequency so that considerable circuit becomes inefficient and generates a lot of noise.
I have seen noise signals from the power cable due to standing waves in the cable.
One can also say that the resistance terminating the cable.

I always have an oscilloscope turned on when I testing electronics.
When the oscilloscope is not used, the probes just lying loose in the vicinity, and there I discover if there suddenly is a radiation - have seen it many times (of cource, I have worked with high frequency in more than 50 years)

/Richo

P.S. By the way - it's a good solution you made
Stations: 584, 585, 2017
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RE: PoE recommendations for System Blue - by RichoAnd - 2016-10-08, 15:56



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