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Electronics => Beginners => Topic started by: Signal32 on April 12, 2021, 02:26:04 pm

Title: Where to find PoE (RJ45) Module or schematic to build one
Post by: Signal32 on April 12, 2021, 02:26:04 pm

Hello,

I'm interested in getting power via Ethernet cable. There is a standard that supports this: https://en.wikipedia.org/wiki/Power_over_Ethernet (https://en.wikipedia.org/wiki/Power_over_Ethernet)
However power is not sent via ethernet by default, a module needs to communicate with the PoE switch and request power.
My question: Are there such ready-build modules that just do the communication with the switch and request power to be sent ? Or can I find a schematic for one ?

I found this on eBay (https://www.ebay.com/itm/CCTV-POE-module-Input-44-57V-PCB-board-output-12V-IEEE802-3af-for-8pin-ip-camera/264046732127?hash=item3d7a69635f%3Ag%3AzRwAAOSwwTtfBQla&LH_BIN=1) but it also has a 12v transformer built which makes it much larger than necessary and which I don't need. Anyone know of a bear-bones module that outputs 48v or a schematic for one ?

Thanks!

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: bingo600 on April 12, 2021, 02:31:45 pm

Something like this ?

5v
https://www.ebay.com/itm/Active-PoE-Splitter-Power-Over-Ethernet-48V-to-5V-2-4A-Compliant-IEEE802-3af/201989618301 (https://www.ebay.com/itm/Active-PoE-Splitter-Power-Over-Ethernet-48V-to-5V-2-4A-Compliant-IEEE802-3af/201989618301)

12v
https://www.ebay.com/itm/Active-PoE-Splitter-Power-Over-Ethernet-48V-to-12V-Compliant-IEEE802-3af-1A-2A/201991194706 (https://www.ebay.com/itm/Active-PoE-Splitter-Power-Over-Ethernet-48V-to-12V-Compliant-IEEE802-3af-1A-2A/201991194706)


Not tested by me , bit they seem quite popular.


Ps: Note the : Compliant with IEEE802.3af 15.4W

/Bingo

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: Signal32 on April 12, 2021, 04:03:42 pm

@bingo600, yes, that's what I was looking for, though the module is kind of large probably due to having to deliver 15W. How can I find a schematic for this - I only need ~3W and would rather build a smaller one myself.

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: kripton2035 on April 12, 2021, 04:04:47 pm

see attached pdf

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: Syntax Error on April 12, 2021, 04:06:43 pm

I've used these TPLink injector/splitter combinations without issue. The injector sends 48 volts and the splitter outputs at 12/9/5 volts, suitable for IP cameras, phones, etc.  They are available as seperates.
https://www.tp-link.com/uk/business-networking/accessory/tl-poe200/ (https://www.tp-link.com/uk/business-networking/accessory/tl-poe200/)

Otherwise, a used managed PoE switch can be found on ebay for around $20. Just be sure it still has it's PoE rated power brick.

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: Signal32 on April 12, 2021, 07:36:07 pm

Thanks, the LAN8710A from @kripton2035 schematic was what I was looking for.

Title: Re: Where to find PoE (RJ45) Module or schematic to build one
Post by: westfw on April 19, 2021, 08:38:39 am

https://silvertel.com/poe-power-over-ethernet-html/ (https://silvertel.com/poe-power-over-ethernet-html/)


Pre-built minimodules.