How to step up 4.95V to 5V?

[wraper]

You can either solder wires instead or power it from the GPIO connector (which is what some RPi PSU "hats" do).

Yeah, that's what I did, power it from the GPIO connector.

That's a bad idea, you are bypassing input protection.

[ogden]

You shall drop idea of 5V PoE because rPI needs up-to 1A or so, voltage drop is too big on Ethernet cable, so you need additional, big& fat power cable. If you need big fat cable - then why don't you just run AC mains to rPI and place power supply right to it? Other option would be to run 24V or 12V PoE and convert to 5V locally using 5V DC-DC switching supply.

[Janne]

I've a project in where I'm powering the PI's direcly from the GPIO connector. I've set up the voltage regulators at 5.1V on those boards and that seems to work wonders in avoiding the low voltage warnings. IIRC Maxium specified voltage of the PI is 5.25 so don't up the voltage too much..

[tsman]

Buy a PoE splitter with a micro-USB plug on it.

That's a bad idea, you are bypassing input protection.

If you're careful and don't overload it or connect it backwards then you're fine to do that. It is mentioned as part of the HAT spec. The MOSFET circuit is just to stop backfeeding 5V on the micro-USB power socket. They removed it entirely on the 3B+ and it never existed at all on the Zero boards.

[Cerebus]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

[maginnovision]

I've a project in where I'm powering the PI's direcly from the GPIO connector. I've set up the voltage regulators at 5.1V on those boards and that seems to work wonders in avoiding the low voltage warnings. IIRC Maxium specified voltage of the PI is 5.25 so don't up the voltage too much..

Same here. On board 5v regulation fed over 50mil 2oz trace to header connected to gpio caused warning. 5.1v, no warning. 3b+ doesn't have that issue though, the 3b did.

[tsman]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

OP has another thread. They're using the spare pairs to feed 5V to the Raspberry Pi at the end of the cable.

[Cerebus]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

OP has another thread. They're using the spare pairs to feed 5V to the Raspberry Pi at the end of the cable.

Ah, makes sense now.

[IDEngineer]

Fundamentally, the problem here is voltage drop across the rather lengthy cable. That's not a new problem, there are lots of good solutions. Just paralleling more too-small wires is not one of them. The best solution, as recommended several times here by multiple people (including me), is to run a higher voltage over the distance and regulate locally to the load. Not only will this address the voltage drop problem, it will also give you far better regulation performance, lower supply noise, etc. You need to remove that 14 feet of thin wire (yes, twice your seven feet, the *circuit* goes out AND back, remember!) from your "regulated" environment.

[mikeselectricstuff]

DC voltage will drop on long cables, that is why AC is used for power distribution. 

Completely untrue.
It's about the voltage, not whether it's AC or DC

[mikeselectricstuff]

If you need accurate 5V at the device, then the best soution is usually to have a local DC-DC converter at the device, and send a higher voltage (typically  12 or 24V) down the cable. You get less drop due to lower current, and also better tolerance to any drop you do get. 

[Cerebus]

DC voltage will drop on long cables, that is why AC is used for power distribution. 

Completely untrue.
It's about the voltage, not whether it's AC or DC

Erm, current surely? As in I²R losses.

[ogden]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

OP has another thread. They're using the spare pairs to feed 5V to the Raspberry Pi at the end of the cable.

Ah, makes sense now.

It's you. Again. Trying every chance? It's crusade? Shall I become worried?
You suggested me to let it go. Please do the same.

[Cerebus]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

OP has another thread. They're using the spare pairs to feed 5V to the Raspberry Pi at the end of the cable.

Ah, makes sense now.

It's you. Again. Trying every chance? It's crusade? Shall I become worried?
You suggested me to let it go. Please do the same.

It was a simple factual question as I wasn't aware of the other thread, you just happen to the the first, but not only, person to mention PoE. It wasn't even your message I commented to but the second reference to PoE in tsman's. If you think you're being persecuted whenever anybody mentions your name you've got real problems. If you carry on badgering me every time I'm in a thread that you're also in you're going to find yourself pissing off a lot more people than just me - my experience is that the forum doesn't take kindly to that.

[Simon]

Where's PoE and Ethernet cable suddenly come from? I can't see it mentioned previously in the thread until ogden introduced it. 

OP has another thread. They're using the spare pairs to feed 5V to the Raspberry Pi at the end of the cable.

Ah, makes sense now.

It's you. Again. Trying every chance? It's crusade? Shall I become worried?
You suggested me to let it go. Please do the same.

Some sort of paranoia? I don't get your concern.

[mikeselectricstuff]

DC voltage will drop on long cables, that is why AC is used for power distribution. 

Completely untrue.
It's about the voltage, not whether it's AC or DC

Erm, current surely? As in I²R losses.

That's a consequence using a higher voltage to send a given amount of power. 

[XaviPacheco]

I'm happy with all of the possible and good solutions given here. Thank you all. I'm really starting to make physical projects, so encountering these kind of issues gives me experience for the projects to come.

[ogden]

Some sort of paranoia? I don't get your concern.

LOL, no We have history. He is accusing me of "moving goalposts" and derailing discussions (and not only). Please note that he specifically mentioned my nick in his "simple factual question". If you were me, you would suspect that he is coming to accuse me of offtopic talk again. I have rights to be mad as well. I suggested him: let it go. Politely. If needed, I will answer your further questions in PM - if any.

[james_s]

I hate the way they used a micro USB connector for power, almost all of the random cables floating around are inadequate. It would be nice if they had at least provided a space for a barrel jack, Molex or other decent power socket. Even mini USB would be an improvement over micro.

[wraper]

I hate the way they used a micro USB connector for power, almost all of the random cables floating around are inadequate. It would be nice if they had at least provided a space for a barrel jack, Molex or other decent power socket. Even mini USB would be an improvement over micro.

Cables coming with relatively recent smartphones and decent 3rd party charging/data cables work just fine. If you get very cheap crap which does not work with RPi, such crappy cable will also cause smartphone to drop charging current as well. I'd say that you can get decent cable starting from around $2.5-3 if ordering from gearbest.

It would be nice if they had at least provided a space for a barrel jack

Number of blown up RPi would rise several times. It would be real rarity to get a decent 5V PSU with barrel jack to begin with. I bought cheaply more than thousand of customer returned RPi which came from Farnell. 90+% of failures clearly caused by users, not mfg defect. With micro USB you can at least be more or less sure that PSU will have correct voltage and no reverse polarity.

[james_s]

So provide pads for a header, or include an onboard regulator for the 5V like is already there for the core voltage and then it could run from 9-12V adapters. I've had so many micro USB cables that wouldn't work and have seen countless forum posts by users trying to get by with inadequate cables. This is especially true if you want to utilize the onboard USB ports to power devices like hard drives that can draw significant power. I've ended up powering most of my pis by soldering on wires to a barrel jack. I have lots of nicely regulated 5V wall warts.

[wraper]

So provide pads for a header, or include an onboard regulator for the 5V like is already there for the core voltage and then it could run from 9-12V adapters. I've had so many micro USB cables that wouldn't work and have seen countless forum posts by users trying to get by with inadequate cables. This is especially true if you want to utilize the onboard USB ports to power devices like hard drives that can draw significant power.

Increased size of the board, increased cost of BOM. And then deal with all those people with non existing soldering skills destroying their devices. 5V usb is something relatively certain, basically plug and play. 9-12 V adapters can have different polarity and often are not even regulated, simply transformer + rectifier. Some "12V" adapters output 19V without load. It's like opening Pandora's box.

I've ended up powering most of my pis by soldering on wires to a barrel jack. I have lots of nicely regulated 5V wall warts.

Geez, it's not that hard to get a decent cable  ... unless you shop for cheapest garbage. Heck, just buy official RPi cable/charger if you are desperate.

[John Heath]

If you are above doing a dirty trick then there is a quick and easy way out. The trick to a dirty trick is to not talk about it nor put it on your diagram. This eliminates peer pressure with it's long lectures on standard engineering practices. Hey this is a nerd project not NASA. Place any diode on you bench on the 7805 regulator ground. The regulated voltage out should now be 5.6 volts  rather than 5 volts. This extra .6 volts should be enough to prevent the pi brown out condition. You did not hear this from me as I would never stoop to such dirty tricks.

[wraper]

If you are above doing a dirty trick then there is a quick and easy way out. The trick to a dirty trick is to not talk about it nor put it on your diagram. This eliminates peer pressure with it's long lectures on standard engineering practices. Hey this is a nerd project not NASA. Place any diode on you bench on the 7805 regulator ground. The regulated voltage out should now be 5.6 volts  rather than 5 volts. This extra .6 volts should be enough to prevent the pi brown out condition. You did not hear this from me as I would never stoop to such dirty tricks.

Don't forget to cool that poor 7805. And in case of Rpi3/3+ it likely will trigger current protection of 7805, especially if you attach some USB flash.

[tooki]

Update: I've changed the cable again and it works well now. Apparently, I have serious issues identifying a good cable for my application.

FYI, cat6 and cat7 cables use thicker wire than cat5. Helpful for PoE — Though as you’ve seen, at 5V, you need really, really thick wire. It’s much better to run a higher voltage at lower current across the wire (e.g. 24V) and then use the DC-DC converter locally.