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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?
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?
It seems like you just need to combine your POE adapter with a USB "lipo" adapter.
The latter are meant to attach to a lipo battery (7.4V - 22.2V) and provide 5V for USB charging.
(Of course, you can use any DC power source as input, not just lipo batteries.)
You can search Ebay for "usb lipo mobile charger" to find them, starting at $5 for basic ones.
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
you've mentioned PoE, USB and 12V power sources. what you failed to mention is what the hell you actually want. do you want PoE to 12V? do you want PoE to USB? do you want an SBC powered by PoE that boots off a USB stick? what the hell do you want?
Anons need not reply. Questions end with a question mark.
Are you kidding? A device standard that supplies 5V but needs VERY precise 3.6V on its data lines? A device standard where the protocol is VERY picky with its timing and pretty much requires you to either use silicon that can talk USB out of the box (which then requires a bunch of very funky additional bits and pieces and you may hope that it's not only available as BGA, you may dream about getting a DIL chip) or requires you to write very well timed assembler code and STILL would require its own chip if you dare to clock it at less than 20MHz... provided USB 1.1 is enough for your needs. You want more? You better have a way to pump 50+MHz out of that chip.
USB may be much. It's very user friendly and "plug and play" and whatnot, but one thing it ain't: A hobbyist's wet dream.
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
POE is massively less common than 12V and you can build a 12V wifi controlled switch for less than $5.00 Anything commercial will be a very very niche device and will cost a lot.
What is more common, 120-240V AC. That is the absolute most common power on this planet. and Ethernet controlled AC switches are plentiful and easy to get.
Stop being a cheap bastard and buy one. $79.00 on amazon.
http://www.amazon.com/gp/produ...
If that is too expensive, then build one from a MSP8266 or get a better job.
Do not look at laser with remaining good eye.
How the hell did this rambling incoherent question get posted to the FRONT PAGE of Slashdot?
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
âoeWho knew something as harmless as willful ignorance could end up having real consequences?â
The summary suggests that POE is a "ubiquitous power source", but the suggests that we have to go to [redacted] to take a chance on getting one. Which is it?
Just because someone names one possible place a thing can be bought doesn't preclude it being massively available via other channels.
But you knew that. You just wanted to spew a buzz-word you made up. Twice in one thread. Well, sorry, you're getting called on it.
"Oh no... he found the
There's a lot of POE "standards" some ranging up to 57V - make sure you know what you're getting into when you start plugging and playing:
https://en.wikipedia.org/wiki/...
Thats not true 802.3af poe though, thats hijacking unused cores of the cat5 to use for power.
Works, though
It will also leave you with the same issue of how to power cycle remotely.
Life is tough all over. That one isn't too hard to solve with another little device, maybe a nano with an ethernet shield and a relay board.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
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.
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...
Everything I write is lies, read between the lines.
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.
If you read the PoE spec, you'll see that the power is sent on both wires of at least two pair, and because the electrical spec calls for transformers on the receive end, the power will cause no issues. Since there's no voltage difference between the wires in the same pair, there's no problem with core saturation. For non-PoE devices, there's no difference. For PoE devices, the receive transformer has a center tap to access the power.
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.