USB for Power?
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(Apologies for the repeat --- I posted this in the Lounge yesterday, before someone pointed me to the proper forum) For those in DIY electronics... Exactly how good is USB for providing power to a device? I specifically mean devices that are not attached to a computer and use the USB cable strictly for power. I've long felt that we need a standardized low-voltage DC power source coming right out of our walls, much in the manner that we currently have 120V (or 220V) AC coming out of our walls -- to eliminate the need of all those "brick" power adapters cluttering our power strips. The last time I discussed this publicly (about 10+ years ago), I was scoffed, with the reason being every device uses a different voltage. (I rejected that, as AC devices were able to adapt to use 110V, so DC devices could adapt to use the standardized voltage). The real problem was that every device used it's own plug size (and selling the proprietary adapter was a profit center). However, now there's some movement to power things with USB cables. So, the question for the electrically minded here: If all you had available to power your device was an USB cable, would that be viable?
Truth, James
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(Apologies for the repeat --- I posted this in the Lounge yesterday, before someone pointed me to the proper forum) For those in DIY electronics... Exactly how good is USB for providing power to a device? I specifically mean devices that are not attached to a computer and use the USB cable strictly for power. I've long felt that we need a standardized low-voltage DC power source coming right out of our walls, much in the manner that we currently have 120V (or 220V) AC coming out of our walls -- to eliminate the need of all those "brick" power adapters cluttering our power strips. The last time I discussed this publicly (about 10+ years ago), I was scoffed, with the reason being every device uses a different voltage. (I rejected that, as AC devices were able to adapt to use 110V, so DC devices could adapt to use the standardized voltage). The real problem was that every device used it's own plug size (and selling the proprietary adapter was a profit center). However, now there's some movement to power things with USB cables. So, the question for the electrically minded here: If all you had available to power your device was an USB cable, would that be viable?
Truth, James
If you want to power from any USB port you come across, the limit is 5V at 500mA. USB 3 muddies the water a bit with 900mA max. Then there are ports that can be dedicated charging ports with limits up to 20V and 1500mA or more, but those require negotiation logic on your device end to get the port to deliver it.
Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak -
If you want to power from any USB port you come across, the limit is 5V at 500mA. USB 3 muddies the water a bit with 900mA max. Then there are ports that can be dedicated charging ports with limits up to 20V and 1500mA or more, but those require negotiation logic on your device end to get the port to deliver it.
Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave KreskowiakSo, is there an option where you just splice the wires together and get power (like with AC), or does it always require negotiation logic?
Truth, James
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So, is there an option where you just splice the wires together and get power (like with AC), or does it always require negotiation logic?
Truth, James
Yes. All USB ports will supply 5V at a max of 500mA (900 for USB 3) without any negotiation.
Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak -
Yes. All USB ports will supply 5V at a max of 500mA (900 for USB 3) without any negotiation.
Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave KreskowiakIs 5V at 900mA (If we're going to standardize, it might as well be on USB 3) sufficient for a reasonable number of household (non-computer related) tasks? I'm assuming space heaters are out, but what about small lamps, fans, clocks?
Truth, James
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Is 5V at 900mA (If we're going to standardize, it might as well be on USB 3) sufficient for a reasonable number of household (non-computer related) tasks? I'm assuming space heaters are out, but what about small lamps, fans, clocks?
Truth, James
Probably. The USB 3.0 spec has been around since about 2008, so motherboards would support for it for at least 10 years now.
Asking questions is a skill CodeProject Forum Guidelines Google: C# How to debug code Seriously, go read these articles.
Dave Kreskowiak -
(Apologies for the repeat --- I posted this in the Lounge yesterday, before someone pointed me to the proper forum) For those in DIY electronics... Exactly how good is USB for providing power to a device? I specifically mean devices that are not attached to a computer and use the USB cable strictly for power. I've long felt that we need a standardized low-voltage DC power source coming right out of our walls, much in the manner that we currently have 120V (or 220V) AC coming out of our walls -- to eliminate the need of all those "brick" power adapters cluttering our power strips. The last time I discussed this publicly (about 10+ years ago), I was scoffed, with the reason being every device uses a different voltage. (I rejected that, as AC devices were able to adapt to use 110V, so DC devices could adapt to use the standardized voltage). The real problem was that every device used it's own plug size (and selling the proprietary adapter was a profit center). However, now there's some movement to power things with USB cables. So, the question for the electrically minded here: If all you had available to power your device was an USB cable, would that be viable?
Truth, James
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Is 5V at 900mA (If we're going to standardize, it might as well be on USB 3) sufficient for a reasonable number of household (non-computer related) tasks? I'm assuming space heaters are out, but what about small lamps, fans, clocks?
Truth, James
Clocks would be fine, Very small lamps (some LED Only?) and anything bigger than a novelty with a motor or tries to change a temperature will eat more amps than what USB ports deliver or cables are designed to carry. I encourage you to continue your research though; please review motor home or camper power use - in many cases it's 24V DC and may answer many of your questions for how and what. Or better yet, invent motors or heating elements that are actually practical and only require < 1 amp and 10V to run- that would make you a fortune! Cheers, Craig
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Too many small ends for someone to stick into the wrong outlet.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food
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Too many small ends for someone to stick into the wrong outlet.
It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it. ― Confucian Analects: Rules of Confucius about his food
you can get GPS tracker on discount Vyncs promo code 35% Discount | Amazon Coupons Grabber[^]
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Is 5V at 900mA (If we're going to standardize, it might as well be on USB 3) sufficient for a reasonable number of household (non-computer related) tasks? I'm assuming space heaters are out, but what about small lamps, fans, clocks?
Truth, James
You've got 4.5 watts. Check the power requirements for your devices. A 4.5 W fan isn't much of a fan. 4.5 W of LED light is bordering on the usable. A plain clock can easily run on 4.5 W, but if you are thinking of one with light and radio to wake you up to and animated display and so on, maybe it will break the power limit. Usually you can find the power consumption on some label. And then: What you get without negotiation is five volts. If you want to adapt existing electronics, they may be built for two AA batteries, three volts, or for twelve volts. Some are for nine volts. So you will have to add some voltage regulator. Then you might consider adding a chip for USB power negotiation as well, and you will have the option for both higher voltage and higher effect. I wouldn't have gone for USB as a low-voltage distribution system, though. Specifically: I am not going for it, I go for 12/24 V. I am in the process of stretching cables from the accumulators of my solar panels to sockets "all over the house". I go for far more robust plugs than USB-C; they will be XLR, probably 3-pin with ground, 12V and 24V. Before I start buying the sockets, I will again consider 5-pin, with a pin for 5V. The 12-to-5V converter will be right behind the socket, no 5V cabling, so maybe I rather put that converter outside the wall. I will put together various cables with XLR plugs for the wall side (usually the angled variant so it won't stick too much out), and various plugs / sockets in the other end: The common 12 VDC adapter plugs, the car cigarette lighter socket type etc. You can find most plug/socket types e.g. on Mouser. At low voltage - definitely at 5V - the current for a given effect is high. The USB wires are thin. The losses are high. You cannot run long cables. That is why I added 24V alongside with 12V - actually, I've got 24V only from the accumulators to each floor, to a 24-to-12V converter. I am careful to minimize cable lengths: A "spine" along the middle wall through the house, fed from the middle. From the spine run "ribs" to the sockets, mostly on the center wall, or in a right angle out to a ceiling lamp. - Yet, I am using 4 sqmm cable for the spine, 2.5 sqmm for the ribs. I do not know the wire gauge used by USB-C, but it is a tiny fraction of this. For the cables, I might use thinner conductors; that depends on length and expected power consumption. Each rib will be protected by a fuse corresponding to the expected power drawn on that rib. Note that the