Ask Slashdot: Affordable Hardware For Remote-Booting USB Devices?

phlawed writes: USB ports are everywhere. It is very convenient for powering low-power devices, and by using a run-of-the-mill phone charger you can easily get 10+ watts or so. In other words: everyone already has the generic power supply and power cable. No issue with voltage or polarity. Perfect for the hobbyist market.

Another ubiquitous power source (in the enterprise environment) is Power over Ethernet. Active PoE splitters for 12V output are available for ~6-7 USD and up on eBay. With PoE you get networking and power over the same wires, and booting your (possibly borked) PoE device is a matter of instructing the PoE source to cycle the power on that port. (Also, USB chargers with 12V input are available for less than 1 USD on eBay. They are likely all crap, though.)

I am looking for the combination of these two concepts in a compact, affordable, quality product. I found one product offering USB power from PoE. That product appears to have left out Ethernet and has a MSRP of 30 USD. Otherwise, I find PoE wall sockets for a MSRP of USD 100 or more. It appears excessive, given the cost figures of the pieces listed above.

So, if it does not already exist... anyone feel like running with this on your favorite crowdsourcing platform? Any experienced electronics people who can do a back-of-the-envelope calculation for cost of parts and assembly?

Comments

Dafuq?

[Anonymous Coward]

What dafuq are you actauloly looking for. You spent so much time describing supposedly unwanted stuff, that I can;t figure out what you want.

It sounds like you want a PoE device that provides USB power, but you're a cheap bastard and $30 is too high for you. So...
$19 http://www.ebay.com/itm/iDocx-iPower-POE-to-USB-Converter-/181992770079?hash=item2a5f9d4a1f:g:eioAAOSwqrtWmVbu

$21 http://amzn.to/1nIeoNw

Dear Timothy...

[Anonymous Coward]

How the hell did this rambling incoherent question get posted to the FRONT PAGE of Slashdot?

$17 Bucks

[stinkydog]

http://www.amazon.com/WT-AF-5v...

Did not take much google fu to find this sucker. 5v output from POE and passthrough to boot.

SD

Re:bay of thieves

[Anonymous Coward]

Voltage drop becomes quite a problem on Ethernet when it used as power over medium to long distances. The expensive gear runs higher voltage (56v) and then the PoE devices to suit the standard regulate the power at the other end. This is necessary. The higher voltage also keeps the amps down for efficiency on the thin cat5e/6 cable. This is the same reason mains power is the voltage that it is for delivery in to your home/office.

I have attempted to run a Wifi AP with homebrew PoE mounted in the roof of my property doing as the OP suggested but the voltage drop was too great over about 10 meters. I did manage to get it working, but I needed more voltage than the original PSU supplied and then needed to solder in a voltage regulator where I split the power out of the Ethernet cable and before the device.

There can also be regulatory issues with power and data. Usually low voltage power does not count as power so you should check local laws. Here, power and data are legally meant to be 10cm apart to prevent safety issues when cable damage cuts the insulation and shorts the data and power pairs together.

Also, be aware the gigabit ethernet does use all pairs. If you liven up the unused pins for your 10/100 (especially at higher voltages) dont accidentally plug it in to a gigabit port. Damage to the port will likely follow.

PoE is convenient with proper planning but you cant over simplify it and it may be more of a burden / cost than the OP expects.

Re: bay of thieves

[ls671]

Damn, I didn't know that, you have just trashed my project. I have been working for 3 years on a concept where Ethernet cables would be used to transmit power on the power grid thus saving on copper wires costs. I intended 2000 MW. What a bummer...