Power Over Ethernet Splitter Improves Negotiating Skills

Implementing PoE is made interesting by the fact that not every Ethernet device wants power; if you start dumping power onto any device that’s connected, you’re going to break things. The IEEE 802.3af standard states that the device which can source power should detect the presence of the device receiving power, before negotiating the power level. Only once this process is complete can the power sourcing device give its full supply. Of course, this requires the burden of smarts, meaning that there are many cheap devices available which simply send power regardless of what’s plugged in (passive PoE).

[Jason Gin] has taken an old, cheap passive PoE splitter and upgraded it to be 802.3af compatible (an active device). The splitter was designed to be paired with a passive injector and therefore did not work with Jason’s active 802.3at infrastructure.

The brain of the upgrade is a TI TPS2378 Powered Device controller, which does the power negotiation. It sits on one of two new boards, with a rudimentary heatsink provided by some solar cell tab wire. The second board comprises the power interface, and consists of dual Schottky bridges as well a 58-volt TVS diode to deal with any voltage spikes due to cable inductance. The Ethernet transformer shown in the diagram above was salvaged from a dead Macbook and, after some enamel scraping and fiddly soldering, it was fit for purpose. For a deeper dive on Ethernet transformers and their hacked capabilities, [Jenny List] wrote a piece specifically focusing on Raspberry Pi hardware.

[Jason]’s modifications were able to fit in the original box, and the device successfully integrated with his 802.3at setup. We love [Jason]’s work and have previously written about his eMMC adventures, repairing windows tablets and explaining the intricacies of SD card interfacing.

New Cross Bladed Axe Not For Cosplay Or Larping

Firewood aficionado and general axing enthusiast [KH4] likes to cut and split his own fire wood. To burn a tree trunk sized piece of wood efficiently, it has to be split into 4 smaller pieces. [KH4] does this with 3 axe swings, the first splitting the main log in 2, then splitting each half in half again. Although he likes swinging the mighty axe, he still would like to increase the efficiency of each swing.

Well he’s done it! This is accomplished by making a Cross Bladed Axe that has an X-shaped head. Each axe swing should split a log into 4 pieces. That results in 66% less swings for the same amount of wood split!

This projected started with two spare axe heads. One was cut in half with an angle grinder. The two axe head halves were then ground down so that they match the contour of the original axe head. Once the fit was good, the welder was broken out and all 3 axe head pieces were combined into one beastly mass.

After the new head was polished and sharpened, it was re-assembled a new hickory handle. We have to say, the end product looks pretty awesome. There’s a video after the break of this axe in action. Check it out!

Have you ever seen how these axe heads used to be manufactured?

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Making Structured Wiring Do Your Bidding

So you’ve just moved into a home that has cat5 running throughout. This is called structured wiring and is a great feature for a home. But what if the existing wiring doesn’t work the way you would prefer to setup your network? [Firestorm_v1] has a workaround that lets you reconfigure Ethernet without pulling new cables.

He’s making splitters out of patch cables. Often, Ethernet devices are not using all eight conductors in the cable. Unless you are using Gigabit Ethernet, or running Power over Ethernet, only four of the conductors in each run are being utilized. This means you can create twice as many connections without running new cable or using addition switches. Each splitter has three RJ-45 connectors on it. One of them hooks to the wired jack in the wall while the other two hook to two different devices. You’ll need a second splitter to use on the opposite end of the wall jack, usually this is where the router or switch is located, in order to separate the combined signals.