So Where’s My Low Voltage DC Wall Socket? • Hacker News Board

Re: So Where’s My Low Voltage DC Wall Socket?

#21

Post by rb808 » Mon, Dec 16, 2019, 4:52 PM UTC

I dont think DC wall socket is the problem - its the small electronics that each have their own power pack.

Ideally to me every led lamp, settop box, alarm clock, phone, laptop would not come with a power supply box. It would just take a USB cable or similar standard. Then you could buy a good quality power supply adapter that you can reuse for lots of products - and avoid the abundance of random adapters everywhere.

Re: So Where’s My Low Voltage DC Wall Socket?

#22

Post by pjc50 » Mon, Dec 16, 2019, 4:52 PM UTC

ethagknight wrote: post #10

Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any…

That sounds like the sort of thing your local electrical code authority might get very upset about. It's not clear what the actual voltage is? But if it's over "SELV" ratings different rules are going to apply.

Re: So Where’s My Low Voltage DC Wall Socket?

#23

Post by allovernow » Mon, Dec 16, 2019, 4:54 PM UTC

ethagknight wrote: post #10

Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any…

Looks like buzzword marketing bullshit to me. Apparently they're just sending pulsed DC power over Ethernet cables? Nothing else in that article is as new or exciting as they dressed it up to be. GFCI outlets are standard in modern houses, they claim to be safely transmitting "high voltage" but 120V is not, and the "digital" buzzword stinks of marketing.

>It transfers high levels of power over non-power cable

You can't beat physics. Wires heat up from current, regardless of whether it's AC, DC, or "digital" pulsed DC. I doubt Ethernet cable is rated for any significant amount of power, but searching for "cat6 max power" doesn't return any relevant results because search is broken in 2019.

It's also likely to be rather inneffecient, as they are converting from AC to DC and then potentially back to AC? There may be an advantage to pulsing DC but I'm not sure, typically AC is more efficient for power transmission because of lower losses for the same power over distance and higher transformer efficiency (no need for an inverter).

Re: So Where’s My Low Voltage DC Wall Socket?

#24

Post by gmueckl » Mon, Dec 16, 2019, 4:55 PM UTC

Danieru wrote: post #15

ethagknight wrote: post #10

Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any…

Oh wow, I would not want 2000w going through Ethernet. Both for the obvious electrical issues, and for the dangerous mixing of safe sockets and hot sockets. No idea how this would be more efficient. Bursting voltage will lead to higher loses versus a continuous voltage. Are they claiming efficiency thanks to a centralized AC->DC converter?

Cat5 doesn't imply RJ45, so that confusion could be easily averted if people with brains developed that stuff. 2000w constant power transmission on a Cat5 sounds dubious, though. I don't know at what the voltage such a cable gives in and shorts wires. It would have to be pretty high to get the current to something the wire crossection can handle.

Re: So Where’s My Low Voltage DC Wall Socket?

#25

Post by mark-r » Mon, Dec 16, 2019, 4:56 PM UTC

theandrewbailey wrote: post #16

> ...and incorporate a fuse to protect the appliance cable from fire. Those British BS1363, fused-mains-plug habits die hard. Lots of car barrel connectors have fuses inside. I'm not seeing much reasoning behind not using the car barrel connectors, aside from 'it was designed for cars, not as a general purpose connector'.

Car connectors are ugly, oversized, and mechanically questionable. They do work though - I once used one to hook a solar cell to a 12V fan.

Re: So Where’s My Low Voltage DC Wall Socket?

#26

Post by zwieback » Mon, Dec 16, 2019, 4:57 PM UTC

ethagknight wrote: post #10

Is "Digital Electricity" a real thing? Its billed as an alternative to AC or DC. This may be as good a place as any to ask this question, but I am a hotel developer, and we've had a few people reaching out to us trying to sell "digital electricity" that sends high voltage over cat5 (up to 2000w per the Belden materials) by essentially sending high voltage for very brief blips with the ability to switch off before any…

From the material it sounds interesting but I'd be leery of the 600 Hz switching generating a ton of electrical noise and relying on the upstream systems to keep everyone safe. The idea sounds good but I can see a lot of ways this can go wrong outside of very controlled environments.

Re: So Where’s My Low Voltage DC Wall Socket?

#27

Post by mark-r » Mon, Dec 16, 2019, 4:58 PM UTC

forgotmypwd123 wrote: post #9

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

You could counteract that with heavier wires, but house wiring is already awkward and expensive.

Re: So Where’s My Low Voltage DC Wall Socket?

#28

Post by zzzcpan » Mon, Dec 16, 2019, 4:59 PM UTC

forgotmypwd123 wrote: post #9

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

Well, there is less drop with more copper, so it's more about costs. Cost of cables, DC-DC converters, power supplies and their efficiency determine optimal configuration. Probably going as high as cheap mass market DC-DC converters and PSUs allow is good rule of thumb for low voltage, so like 20-24 V. Beyond that better to go with high voltage.

Re: So Where’s My Low Voltage DC Wall Socket?

#29

Post by gmueckl » Mon, Dec 16, 2019, 5:03 PM UTC

forgotmypwd123 wrote: post #9

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

You have to choose wire gauges carefully. A lot of cables that connect power supplies to their devices have thin wires that don't loae much voltage over the meter or so of cable. But if you woukd extend that with an equal gauge wire to some meters if length, the conmected device will likely burn out around then as well.

Re: So Where’s My Low Voltage DC Wall Socket?

#30

Post by aivisol » Mon, Dec 16, 2019, 5:04 PM UTC

forgotmypwd123 wrote: post #9

I always thought running low-voltage DC through a house from a single supply was doomed due to voltage drop over the distances required....

That absolutely is. You could be better with 48 or even 24 volts, but then you are out of luck if you want to power a majority of devices which are 12v. So your only option is to go for USB-A wall socket which essentially is a wall-wart hidden in your wall. I do not see a good solution here.