Yeah, that's a good point about the speed. I'm using some Raspberry Pi Zeroes, so really I would be shocked if they could even use 100Mbit. (I'm using a USB-ethernet adapter. I like avoiding WiFi.) It makes perfect sense to me that there could be issues with gigabit speeds and dumb devices. :) But using something like that one you linked would double my materials cost right off the bat, and then also require me to buy/build something else to drop the voltage back down. For this simple project it's overkill, but yeah, I can see its benefits.
On Mon, Nov 18, 2019 at 10:14 PM Russell Senior <[email protected]> wrote: > With the end-of-cable splitter, it's possible they'd work, because it would > look like ethernet + barrel connector power, however I have had trouble > when the ethernet cable only supports two pairs for data (because the other > two pairs are used to transmit the power) but both ends think they are > gigabit. Not a problem for Raspberry Pi's (at least not until the rpi4), > but I've had problems with the MR24s with less than gigabit-capable (all 4 > pairs available for data) PoE injectors. The ones I linked are cheap enough > (and cute!) that they've been worth it. > > On Mon, Nov 18, 2019 at 10:08 PM Russell Senior <[email protected] > > > wrote: > > > My experience trying to power the MR24 with "passive PoE" and/or less > than > > 48V were not successful. You really need a standards compliant PoE > > injector for them. > > > > Apparently there is/was a patent on the chips that do/did the IEEE PoE > > standard, which made them too expensive (I recall something like > $15/chip) > > for commodity grade hardware and so price-sensitive vendors like Ubiquiti > > basically said "F-you" and used lower (12-24V) voltage PoE instead. > Meraki > > isn't price sensitive hardware. > > > > On Mon, Nov 18, 2019 at 9:01 PM Erik Lane <[email protected]> wrote: > > > >> If this will do it, it would be a cheap and easy fix. > >> > >> > https://www.amazon.com/BeElion-Passive-Injector-Splitter-Connector/dp/B01HMNJHII/ > >> > >> I've been planning something similar to run a raspberry pi in a location > >> away from a power outlet. Since I don't need hardly any power, the 12V > >> will > >> be just fine even with a long ethernet cord. (Though I'm not going to be > >> all that long, really, just 20ft or so.) > >> > >> It sounds like your use case might be simple enough that something like > >> this would do the trick. (In case it's not clear, one of these goes on > >> each > >> end of the ethernet cable, and then you plug the power pack into the > >> female > >> end and plug the male end into your device, and you're golden.) > >> > >> Good luck, > >> Erik > >> > >> > >> On Mon, Nov 18, 2019 at 6:14 PM Rich Shepard <[email protected]> > >> wrote: > >> > >> > On Mon, 18 Nov 2019, Russell Senior wrote: > >> > > >> > > If you can easily reach the MR24 with a regular ac adapter (12V DC > >> > > output), then the PoE isn't really buying you anything. If you want > to > >> > put > >> > > the MR24 somewhere that is hard to plug into power directly (you > have > >> to > >> > > run ethernet to it anyway), that's where PoE becomes worthwhile. > >> > > >> > Russell, > >> > > >> > It's on the wall about 6' above the floor. The electrical cord is > about > >> > that > >> > long and would need to be longe to reach an outlet. > >> > > >> > Thanks for the insights and lesson. > >> > > >> > Regards, > >> > > >> > Rich > >> > > >> > > >> > _______________________________________________ > >> > PLUG mailing list > >> > [email protected] > >> > http://lists.pdxlinux.org/mailman/listinfo/plug > >> > > >> _______________________________________________ > >> PLUG mailing list > >> [email protected] > >> http://lists.pdxlinux.org/mailman/listinfo/plug > >> > > > _______________________________________________ > PLUG mailing list > [email protected] > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
