there are no standards - and will result in burnt out pi'sSo why not use a regular power connector like a 5.5 x 2.1mm DC power plug, as used in so many other places?
The USB-C does have USB2.0 data connections too.gordon861 wrote: ↑Fri Mar 13, 2020 12:21 pmI figured the non-standardised standard connector would probably be the problem. But considering the power draw for a Pi4 is so high you seem to be stuck with dedicated Pi4 power supplies to ensure you have the required power.
We now have a complicated 22/24 pin plug standard to deliver what could be achieved by a 2 core wire.
The barrel connection is probably not the answer but I don't think USB-C is either.
Since the Raspberry Pi first launched in 2012 the advice has always been to use a good quality power supply that can supply a stable 5V up to and including the load which the particular model of Raspberry Pi you are using places on it. This advice has not changed. For several years now we have also had the option of purchasing an official Raspberry Pi power supply, which takes the guesswork out of this. The official PSU is avaiable at low cost for those people who do not already have a suitable power supply. Many phone chargers do in fact work, for example I have two phones which come with USB-C chargers and they both successfully power the Raspberry PI 4B 4GB models which I have.
gordon861 wrote: ↑Fri Mar 13, 2020 11:59 amSorry if the answer to this is to obvious but, why was the choice made to power the Pi4 via a USB-C connector?
I understand the logic of using the micro-USB on the earlier versions because there are so many power supplies out there that can do the job. But USB-C power supplies that can provide enough power for the Pi4 are so thin on the ground that your choices are limited to ones dedicated to the job and regular USB charges that you plug your own lead into often top out at around 2.0-2.4 amps. Also USB-C male-female extension cables are difficult to find and/or expensive, I assume because a USB-C cable must meet the USB-C specs.
So why not use a regular power connector like a 5.5 x 2.1mm DC power plug, as used in so many other places?
This would open up so many more options to power your system. If you wanted a longer power lead, not a problem. 5 volt DC power supplies are very easy to source so you could use a larger one to power a cluster of Pi4 units.
Again sorry if there is an obvious fault in my thinking but I would love to know the answer..
The barrel jacks can be a world of hurt. Different sizes - external, internal and length. Different voltages and current limits. AC or DC. Polarity. Smoothed or unsmoothed. Regulated or unregulated. Hot or Cold (ok, maybe not that). Not to mention many weird custom versions such as multi pole, and I've seen ones that are a mutant version of Barrel, TRRRS and Phono/RCA in the same plug!Heater wrote: ↑Fri Mar 13, 2020 12:27 pmI love a good solid barrel jack connection as much as anyone. Except as already mentioned there is no standard and it is a world of chaos and pain.
I recently got hold of an Nvidia Jetson Nano and wanted to power it via it's barrel jack.
No probs I thought, I have a box full of wall warts and other power supplies with barrel connectors on their leads. I also have a ton of barrel adapters.
Well, guess what? They were all kind of different voltages. Their barrel connectors were all kind of different shapes and sizes. I could not find one that had the correct voltage and current rating and the correct size/shape connector on it. If I really wanted one I would have to buy it. In the end I cut a lead off one that had the right barrel plug, threw the wall wart away and hooked p the lead up to a 5v supply I had on the bench.
Conclusion: Using a barrel connector would be a really bad idea for the Raspberry Pi's target audience.
Clicking on this link and selecting the type I need tells me "there are no global supplies for this model".That said, I do have a working wart, official or otherwise, I don't really know.fruitoftheloom wrote: ↑Fri Mar 13, 2020 12:28 pm<snip>
https://www.raspberrypi.org/products/ty ... er-supply/
The barrel jack was just an example of an option, considering most people need to use the Pi branded PSU anyways they could have used any type of connector, it only needs two wires.Technocolour wrote: ↑Fri Mar 13, 2020 1:12 pmThe world of barrel jacks is a big non standard jungle, people would blow up thier Pis unless you increased the cost of the power section of the pi, for just about no really good reason.
After the resistor fix, the original thought about being able to use a discarded USB PSU farting around the house is retained.
Nope.pica200 wrote: ↑Fri Mar 13, 2020 3:14 pmUSB-C
On top of that everything is slowly switching to this new connector. microUSB will eventually disappear. Do you need any more reasons?
- is much more robust than microUSB
- can handle more current
- has standardized voltages
- supports the old USB 2.0 interface of the SoC
Yet more pain. Longer lead means more voltage lost on the way, which means more "low voltage" problems for the Pi.
The TVS diode remains in circuit, but there is no polyfuse on the Pi4B. So if you must (IMO, foolishly) use a barrel jack, you should wire an external polyfuse between the socket and the Pi. Then you will have some protection for when you plug in a PSU with the wrong voltage or polarity.
Ah, I suspected the 4B might be different (my 4B uses official supply). I'm still in the older Pi model mindset. I think I have only one Pi powered via GPIO.The TVS diode remains in circuit, but there is no polyfuse on the Pi4B. So if you must (IMO, foolishly) use a barrel jack, you should wire an external polyfuse between the socket and the Pi. Then you will have some protection for when you plug in a PSU with the wrong voltage or polarity.
That would all be compensated for in the design.davidcoton wrote: ↑Fri Mar 13, 2020 4:25 pmYet more pain. Longer lead means more voltage lost on the way, which means more "low voltage" problems for the Pi.
Similar reasons for avoiding switches on the DC power lead.
Compensated by using 12 gauge solid copper wire? Or 24V delivery with a DC to DC converter at the Pi end? What is wrong with using a power strip with a switch and a mains extension cord?bensimmo wrote: ↑Sat Mar 14, 2020 1:43 pmThat would all be compensated for in the design.davidcoton wrote: ↑Fri Mar 13, 2020 4:25 pmYet more pain. Longer lead means more voltage lost on the way, which means more "low voltage" problems for the Pi.
Similar reasons for avoiding switches on the DC power lead.
You would still have 5.1V 3A at the connector.