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Has anyone had any success building a passive ethernet hub with just diodes?

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Freesurfer:
I have an off-grid cabin on solar with a low power router which only consumes around 5W for internet access, which has 5 ethernet ports. Those 5 ports are all used. For extra ports I would need to add a small switch, which can easilly draw another 5W on its own. The aim is to keep the consumption from such devices as low as possible.

Googling around there are schematics for fully passive unpowered "3-way" network hubs built only from a bunch of diodes, which in theory should allow you to split a single port on the router to two devices running at 10/100Mbit half duplex. This may be sufficient just for some low bandwidth smart devices and monitoring devices. Of course there is no signal amplification like you would get from a real hub or switch, the impedance matching is probably not ideal, and there's the challenge of 0.6V diode drops which could greatly reduce the max distance.

(For clarification, it should not be mistaken as an "ethernet economiser" or pair splitter which splits the pairs of a single cat.5/6 cable into two separate ports in each end)

Schematics:

--- End quote ---


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i.stack.imgur.com/RhIgF.gif

magic:
Not saying I know it can't work, but did you find any explanation how it is supposed to work and why it has to be diode pairs, out of all the components in the world? :o

Okay, found some info.
https://electronics.stackexchange.com/questions/10864/building-a-passive-ethernet-hub-with-anti-parallel-diodes
http://www.zen22142.zen.co.uk/Circuits/Interface/pethhub.htm

Maybe...
 :popcorn:

ejeffrey:
This is a 5 port switch that claims to have a max power consumption of 2W:

https://www.amazon.com/TP-Link-Ethernet-Splitter-Unmanaged-TL-SF1005D/dp/B000FNFSPY

It would probably be less when idle with some ports inactive.

ve7xen:
2W max at DC (AC adapter efficiency ignored) is pretty typical for a 5-port switch. The lowest I have seen is that exact unit - 1.87W at the wall, so maybe 1.5W DC; the 8-port version specifies 2.2W at the wall. But 2W is very typical even for GigE units. If it has "Green Ethernet", then idle or link-down ports should save significant power, and even with all ports running, unless they are running at full transmit power (long cable) the actual consumption should be less.

The diode thing might work, it's a clever hack if it does, but it's obviously totally out of spec.

thm_w:

--- Quote from: ejeffrey on December 08, 2021, 10:17:11 pm ---This is a 5 port switch that claims to have a max power consumption of 2W:

https://www.amazon.com/TP-Link-Ethernet-Splitter-Unmanaged-TL-SF1005D/dp/B000FNFSPY

It would probably be less when idle with some ports inactive.

--- End quote ---

Yep, just looking at some random switches: Netgear 8 port claims 3.6W consumption (GS208). Tplink 8 port 2.7W power consumption (LS1008G V2)
Better off getting the extra ports.
edit: missed that original product is a router, so you'd still be adding ~3W draw.. hm

What is wrong with using the ethernet splitter/economiser though?

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