Hi Sudar, On Tue, 28 Oct 2008, Sudev Barar wrote:
> 2008/10/28 shogunx <[EMAIL PROTECTED]>: > > Thanks for the kind words. I am the lead dev on that project If I can > > answer any questions, feel free to ask. > > > > Scott can you give me some pointers on power over ethernet? I have > started google on that but this can answer one endemic problem I have > faced in India - providing a UPS with every terminal. Actually, we deprecated the original non-IEEE-spec PoE hack I made to save a few watts with larger power cabling, and to support larger displays with higher current requirements. Re replaced this with a combo cable... two jackets formed together. One has the 8 wire CAT5, and the other has two pairs of #16 awg wire used for power. I buy that from Metra Electronics in Holly Hill, Fl. It was originally purposed as a home theater cable. You can likely find the equivalent produced nearer to yourself. In the original system with my hack, here is what I did, and it works well: I started with using CAT6 cable, which has 23 awg wire instead of CAT5's 24 awg. The I cracked open the hub, and pulled the motherboard. On the bottom of the board, you can see the 8 pins per ethernet port. pins 4,5,7 and 8 are generally shorted together with a small surface mount capacitor which eliminates noise induced over these unused pairs. First, I remove these capacitors from the board, which isolates each pin from all the others. Then, I add #16 awg wiring, paralleling pins 4 and 5 together for ground, and pins 7 and 8 together for 12VDC positive. Now I have 4,5 soldered together with a black #16 awg lead coming from them, and 7,8 the same with a red lead. I repeat the process for each ethernet port that needs power. All of the reds get put together to a #12 awg wire coming from my battery array positive, and all the blacks similarly soldered together to negative from my batteries. A breaker is placed inline on the positive lead. As a result, you can now plug in an ethernet cable to one of the powered ports, and will have 12VDC across pins 4,5 and 7,8 of your rj-45. Now you have to handle getting that power into your device. You have two options here. The first is modify the device internally, connecting the 12VDC input lead (usually provided by the "wall wart" transformer) to the respective pins on your devices ethernet port... 4,5 for ground and 7,8 for positive. You would do this with jumper wires inside your device. In this instance, the barrel connector for power on the outside of your device would be unused. The second option would be to make special ends for your ethernet cables. This is the method I used. Essentially, you only put wires corresponding to pins 1,2,3 and 6 into the rj-45 connector before you crimp it down. Then, using a barrel connector pigtail which is the correct size for your device, you will solder the wires corresponding to 4,5 to the negative lead of the pigtail, and 7,8 to the positive lead. Make sure to use heat shrink tubing to insulate the connections and strengthen the exposed wire. You can then plug your pigtail into your device, and power it from your battery/solar array. > > Interesting project. Thanx, Scott > > -- > Regards, > Sudev Barar > Read http://blog.sudev.in for topics ranging from here to there. > > PS: I know most of people do not follow email niceties (mostly they > are not aware) but if you follow bottom post/in-line post style of > email conversations it becomes a whole lot easier to carry on > meaningful dialogue and you can snip out what is not meaningful too. > Most people just hit reply button and top post leaving prior message > appended uselessly at bottom. See if you can adopt this style and > persuade others. In case you are already doing this ..... great, > spread the message. > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _____________________________________________________________________ > Ltsp-discuss mailing list. 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