Power-over-Ethernet is for more than IP phones, Wi-Fi access points and surveillance cameras. It can be used anywhere there’s a low-power device that would benefit from continuous power and the reliability of Ethernet connectivity. Assuming your network switch (or POE injector) is connected to a UPS, POE allows the attached devices to remain powered in the event of a power failure.
In my home and office, I use POE to connect and power a number of Raspberry Pi single-board computers configured as music players. The RPi3 B+ isn’t natively POE capable, so I use a POE splitter like the one pictured here.
Given a POE-capable switch upstream, this wee splitter provides 5 VDC at up to 2.4 A via a standard micro-USB connector. This model from Anvision is under $10. A 4-pack is just $37 on Amazon.com.
Turning Monitors On/Off
I have recently found a secondary advantage to leveraging POE for the music streamers. If the RPi is powered over the network it always appears as available to the Logitech Media Server (LMS.) I can use an Amazon smart plug to control power to the associated audio monitors at each location.
Ideally, the smart plug would get a command from the LMS when I start something playing on its associated RPi. That would automatically power up the audio monitors when I start something playing.
While definitely doable, I haven’t quite implemented the server side script to accomplish that level of automation just yet. For the moment, I simply tell the echo to “turn on” the music at that location. A scheduled routine automatically turns off the powered audio monitors late each evening.
Alas, not everything can be powered via micro-USB. In some cases, a slightly different POE splitter is required. This model, also from Anvision, can provide 5, 9 or 12 VDC, switch selectable.
It also has a set of four interchangeable coaxial power tips. This allows it to be configured to power different kinds of devices.
Most recently, I’ve used one to power a very small form-factor computer. The tiny little computer that I have connected to a TV in my office needs 12 VDC at 2A. That’s well within what POE+ can deliver.
I bought this little PC for use at ClueCon 2018. It was to be an NDI playout device, accepting an NDI stream from the network and displaying it on a monitor. In that role it had to have real Gigabit Ethernet and enough grunt to reliably present a 120 mbps 1080p60 stream using Newtek’s NDI Studio Monitor application.
As it happens, I didn’t end up using the tiny computer in exactly that fashion. I have subsequently found the N3450 CPU and its lame-o Intel GPU are not quite up the task. It struggles to display 1080p60 without dropping some frames. That said, it does reliably deliver 1080p30.
I must admit that I’m intrigued by the Ubiquiti Networks Unifi LED lights. These are LED panels intended to fit into T-bar style drop ceilings in offices and industrial buildings. Paired with a mating UniFi Dimmer switcher they leverage 802.3at PoE+ to put the building lights on the network. That means easy remote control and monitoring via the same UniFi controller that tracks your Wi-Fi and managed switches.
Unfortunately, they don’t offer such items in a style that’s appropriate for a home office. It’s probably just as well.
There are clearly defined limits to how much power you can get from a network drop. So, there are cases were power from the network is just not practical. As POE standards continue to evolve the potential for its use expands tremendously.