(07-29-2017, 05:02 AM)dkryder Wrote: yeah, but following that logic you would have read many reports in the forum of pumping 12V or 9V through the pins fried the board
Not so much... too many people are afraid to do that, so either they ask enough questions, or they don't do it. Then there are the ones that got the wires back to front :-O
(07-29-2017, 05:02 AM)dkryder Wrote: using the bigger barrel increases the contact area between the barrel and the jack by ~ 30 - 40 percent. it was essentially a cost decision, ask tllim he probably did not give much consideration if any the the smaller jack decreases overvoltage chances. many users will make a diy larger jack to smaller barrel which totally negates any over-voltage protections.
True, but how significant is that when you have changed from 2 approx 1mm wide by 4mm contacts on the microUSB to the type H barrel jack? We're not talking massive amounts of current here, so I don't think the increase in surface area is needed in this instance. If we were talking about some 6A+ of current, yeah, sure, but not the 1-2A range that the pine64 and other board are in. I do appreciate that the smaller jack won't stop people from DIYing to a larger connector (like I did with a pine64 due to the microUSB connector, but in my case, this was barrel to euler), but it still prevents the majority from doing it. Those people will just buy the cable, and since it's not a standard cheap microUSB, they'll be better off for it. For the others, they can just power via the raspberry pi 5v, euler DC in pins or make an adapter if they are silly enough to do so. And hopefully know a bit about electonics and wiring whilst they do so
(07-29-2017, 05:02 AM)dkryder Wrote: how many power supplies with that size barrel have you seen? i've only seen pine64 power supply. that size barrel is not that common at all in the u.s.a. name 3 other sbc that use it
One of the few other SBCs that I know of that was sane enough to go barrel jack instead of the microUSB was the Cubietruck, and that uses the same size connector (as did all of the other boards Cubieboard made IIRC). As for any others, I don't follow all of them, so I don't know what others have done. I do know the Banana Pi M2 was going the 5.5x2.1mm route, which I see ending in a disaster, but hey, I just know the number of 12v security system 5.5x2.1mm connectors that are around... I don't design and retail SBCs! :-O