What's the 'standard' for lap top power connectors - Page 1
Forum section: electronics / projects

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: May 04, 2017, 11:44:59 am
content: I'm working on a portable Bluetooth Speaker project that needs around 40 Watts (max) of power from a 12 volt battery. Rather than reinvent the wheel, it seems to make sense to use one of the many available 19 Volt switching laptop power supplies; my question is that there seem to be 100 different 'standards' for the diameter of the hole, center pin etc. for the barrel connector that is on the PCB into which the power supply will plug.Can anyone offer any insight into what's most commonly used (i.e. which manufacturer's) and where I can buy the matching PCB-mount barrel connector from?Thanks

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 04, 2017, 11:53:39 am
content: As you stated yourself, there is no real standard. I've even seen manufacturers switch to rectangular connectors aswell (I first saw it with Apple's magnetic connector, followed by lenovo. I've also seen non-circuilar ones on DELL and HP laptops, and then there is that "thing" (although great in terms of ease-of-use) the microsoft surface uses...)Most distributors or electronic stores will sell one form or the other. What I've actually started doing is use non-circuilar connectors (RC connectors for example) to avoid people plugging in wrong powersupply voltages.Also keep in mind that those laptop powersupplies can be very very in terms of noise performance. I've spent a weekend trying to find the cause of (what seemd to be) oscilations on a analog circuit, when it turns out it was just my powersupply ripple (on the order of hundreds of mV!) feeding through into my reference circuit.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 04, 2017, 12:24:26 pm
content: I would select a generic 19-20 V replacement laptop supply that has reasonable prospect of longevity (good luck with that) and standardize on that connector. I am in a similar position and after months of pondering and researching, I believe that is what I will be doing.

author: Jeroen3
author_rank: Super Contributor
timestamp: May 04, 2017, 01:29:22 pm
content: USB 3.0 Power Deliverywill be. Dell is already using them (USB C) on their docks. And a smaller variant of their barrel plug.

author: mrratburn
author_rank: Newbie
timestamp: May 04, 2017, 02:17:53 pm
content: I have a Sony portable bluetooth speaker that charges with a 12V power supply. The connector is just a standard DC jack and it comes with a wall-wart type charger. I suggest you stick with this in your device (using center-positive configuration) since this is the most common and universal way of getting 12 volts in all the devices I've seen.Also from a product design perspective, you cannot assume the user has a laptop lying around to use the charger for your speaker. Most people use these type of devices with theirsmartphoneafter all.You could use one of these for example, just make sure you don't exceed about 80% of the stated current rating because it will let you down.https://www.amazon.com/BINZET-Supply-Adapter-Converter-Regulator/dp/B00VA27NRK/ref=sr_1_3?ie=UTF8&qid=1493907400&sr=8-3&keywords=12v+5+amp+power+supply

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 04, 2017, 03:40:19 pm
content: Quote from: mrratburn on May 04, 2017, 02:17:53 pmBut that is the presenting problem here.There is NO "standard DC jack".As the old joke goes: "That's the nice thing about standards. There are so many to choose from."

author: Siwastaja
author_rank: Super Contributor
timestamp: May 04, 2017, 06:29:11 pm
content: Re "standard DC plugs", there are about about 20 typical "standard" DC plugs almost equally common, some of which are so close to each other that they kind of work but the contact isn't tight, giving occasional outages, heating and sparking.Ever bought one of those universal transformers withdozensof plug adapters, only to find out that none in the set fits? Yup.Add the fact that some equipment uses positive barrel convention - especially in older stuff, so everything designed for "standard DC plug" needs to be designed with reverse polarity protection.Quite frankly, these "standard DC plugs" are always designed to only be used with the manufacturer-supplied supply. Everything else is by luck, and on one's own risk. OP should probably do the same, and pick some Meanwell or similar easily available, acceptable quality standard off-the-shelf PSU with spec sheet showing the exact connector type. Then supply this PSU with your product.For the end user, hunting for a compatible PSU is a waste of time no one wants, and there is no easy solution for this, unfortunately. 5V through micro USB comes close, but nothing in the higher-voltage, higher-power segment.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: May 04, 2017, 06:57:28 pm
content: Quote from: Richard Crowley on May 04, 2017, 03:40:19 pmWhile I agree somewhat, the supply in the link he posted uses a 5.5 x 2.1mm center positive barrel plug, which is by FAR the most common. This is the plug you see in basically every piece of networking equipment (the ones that are DC powered) and most desktop electronics (clocks, radios, etc). I have no fewer than 5 different devices on my desk right now that use this plug, 1 that uses USB, and the rest are AC or battery powered. IfanyDC plug/jack could be considered the "standard", that's it. Not for laptops though, they're all proprietary, at least until USB-C takes over.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 04, 2017, 08:01:27 pm
content: Quote from: suicidaleggroll on May 04, 2017, 06:57:28 pmMaybe. IME, there are just as many 5.5 x 2.5mm connectors out there, and they are NOT inter-operable.My greatest concern about Radio Shack folding is that there is no replacement for their quite extensive range of "Adaptaplug" wall-wart connector options. The storefronts had a large bundle of perhaps 3 dozen different plugs that you could test on your orphan gadget. Then you could note which letter fits your gadget and buy the appropriate mating plug along with a generic wall-wart. There is no substitute for actually having the test plugs in hand to try in your gadget. Even if somebody continues to offer all the different sizes online, there is no easy and reliable way to test exactly which size you need, at least not over the internet.