PoE for Raspberry Pi for under $2 • Hacker News Board

Re: PoE for Raspberry Pi for under $2

#11

Post by oakwhiz » Sat, Sep 28, 2019, 6:29 PM UTC

funvill wrote: post #3

be careful POE can be anything up to 48 volts. Unless you control the input voltage. I suggest using a DC-DC converter with a larger input voltage.

Regular PoE can in some cases get as high as 56 volts... Some PD equipment is overspec'd to deal with regulation issues on PSEs.

Re: PoE for Raspberry Pi for under $2

#12

Post by philcrump » Sat, Sep 28, 2019, 7:09 PM UTC

jononor wrote: post #9

Has anyone found proper PoE injector/extractors modules that do negotiation (not passive) at a decent price?

The "DSLRKIT" splitters that are around on Amazon are reasonable in my experience, although the nominal output voltage varies by upto 10% between units.

The 802.3at-specced ones are a little more efficient than the af for the same power draw, I'm using them at home in a couple of applications where I'm feeding 802.3af but the power budget is cut a little close.

Re: PoE for Raspberry Pi for under $2

#13

Post by tjoff » Sun, Sep 29, 2019, 8:21 AM UTC

aaronax wrote: post #10

tjoff wrote: post #5

Earlier quoted context omitted.

It is passive POE, you need to supply your own input as it won't work with a POE switch or anything like that.

There are some switches that supply passive PoE, such as many of Ubiquiti's products.

Sure, but you have to explicitly enable it. When would you not have control over the input?