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0 pointsMisterTea6y ago0 comments

Why? Routers, switches, small embedded computers, and a myriad of devices already use 12-24V DC and step it down internally to 3.3V or less for chip use. Laptops and even phones/tablets are no different. And conversion losses don't increase with voltage so long as you design your DC-DC converter properly.

5-6V is fine for small loads of around 10 watts but you then have to deal with line losses. A 5 m / 16 foot 24 AWG usb cable will lose 38.5% of its power from line losses at 5V, 2.5A (a measly 15 watts). If you wanted to get a low 2-3% loss for 5V, 2.5A at 5m cable length you would need 12 AWG which is massive. 24V does better but if you wanted 50+ watts you again have voltage drop issues.

So in conclusion, low DC voltages are not very practical for power cable runs of over 2 meters. Though it would be nice if the last meter could be more unified with a single DC voltage and connector (my vote is for 24V). Then we can consolidate multiple devices to one strip/brick and call it a day.

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hyperman16y ago

That's true. My aging but still well-functioning WRT54G router had its 12V 2A wall wart die on me last year. At the same time, some USB cable had its micro B end accidentally ripped of.

So I thought, why not, opened the router,and lo and behold, the DC circuit is perfectly happy with 5V and 1.2A or so, and converts it down to I believe 3.3V.

So I drilled a hole in the router and soldered the working end of the damaged cable to the power input. Other end is pluggend into the useless USB TV port. Has been working fine ever since. Neither TV nor router runs hot, which I couldn't say about the old wall wart.

In theory, USB should negotiate the required amount of power It turns out the TV manufacturer decided to simply wire the port directly to the internal 5V rail connected to both USB ports, so it should be able to give at least 2x2A.

Yeah, it was probably cheaper to just buy a new router. Got a bit nerd-sniped there I guess ;-) .

Scipio_Afri6y ago

Should've let this thing die. Do you actually have devices hooked up to this.. the speeds you're getting and the likely security holes you have (especially if you don't have this properly behind some other device) are concerning me.

hyperman16y ago

Dont worry, there is a decent enough firewall built in to the ISP modem. And my ISP is more than slow enough that the speed of the router doesnt matter much. And when all my computers are off, so are the router, the modem, the TV and all the other stuff.

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0 pointsMisterTea6y ago0 comments

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hyperman16y ago

That's true. My aging but still well-functioning WRT54G router had its 12V 2A wall wart die on me last year. At the same time, some USB cable had its micro B end accidentally ripped of.

So I thought, why not, opened the router,and lo and behold, the DC circuit is perfectly happy with 5V and 1.2A or so, and converts it down to I believe 3.3V.

Yeah, it was probably cheaper to just buy a new router. Got a bit nerd-sniped there I guess ;-) .

Scipio_Afri6y ago

hyperman16y ago

j / k navigate · click thread line to collapse