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Forum Index : Microcontroller and PC projects : USB cables as power chords
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CaptainBoing Guru  Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
Interesting examination from Andreas Speiss on the quality of USB chords and their impact on power delivery. As a lot of us use them to get power to our projects (at least in development) I thought I would post this as a cautionary tale - I have certainly had "ghost" problems that are eliminated when using a "proper" power connection instead of the USB lead... got one on my desk as I speak. https://youtu.be/n70N_sBYepQ |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
I'm sure you mean 'Cords'.....  Power chords can certainly be provided by any hard-rock guitarist.  On the cables though, if you are wanting to power a Pi or even any of the Micromite series of boards, I highly recommend a quality cable from the likes of Jaycar. Their USB cables are to spec, and can pass a couple of amps no problem - even the long ones. The super-duper cheap USB cables on eBay et el, and cables that come free with cheap products do tend to be more often then not, utter rubbish. One cable I cut open had four hair-thin enamelled copper wires inside. They were tiny. The USB data lines GENERALLY won't care too much so long as there is a connection present, but the power ones really DO care. A-lot in some cases. The video is quite right - it's all about voltage-drop under load. The cheap cables are like adding 1k resistors in series with the power supply, and the more current you need, the worse they are. I can qualify my remarks by stating that more then a couple of people have had problems getting their E100 boards to work - even without an LCD connected - when trying to power them via USB and installing jumper shunt J1. It is always the USB lead. When they get a decent quality USB cable, everything magically works! Smoke makes things work. When the smoke gets out, it stops! |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
! live and learn ! " Here's an easy trick to remember the difference. You can remember that chord deals with musical notes that are in harmony. Harmony and chord both have an “H” in them. Cord refers to a rope, both of which are four letter words. " cheers grogs  |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9750 |
No offence. I was just getting the boot in while I could.  Smoke makes things work. When the smoke gets out, it stops! |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2171 |
... and none taken, chubby I always leave my ego at the door and happy to be shown I have something wrong and will (in the absence of any rebuttal) modify my thinking accordingly in the interest of personal advancement... |
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| hitsware Guru Joined: 23/11/2012 Location: United StatesPosts: 535 |
I have found both the length and ' quality ' ???? of USB wires to my RPis affects how often and if the low voltage indicators come on ..... |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
I have been through a lot of junk cables but having great results with: https://www.juicebitz.co.uk/ Heavier conductors and connectors that have a nice, secure click. |
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| VK2MCT Senior Member  Joined: 30/03/2012 Location: AustraliaPosts: 120 |
I was once troubleshooting a cheap flatbed scanner. It got power from the USB cable, rather than having a separate power supply. Used close to 1 amp up the USB as I recall. After lots of wasted hours, it turned out to be a stuffed cable. John. |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 816 |
Its not surprising, I have a usb here I cut into pieces for a project and the wires inside are only a mm in diameter, and when you look at the insulation, its thicker than the copper inside- it would be well under 0.5mm. I mentioned in another thread that I am also suspicious of the microB usb connections after testing several old (1 yr old plus)leads that were still sealed in their packages, never used and 3 of the 4 tested had failed connections in the microB plug end (all different brands) I suspect they have a crimp style connection that corrodes internally, only because of the high failure rate of unused cables that had been in storage for a while (they were in a box of cables in my back bedroom so no real reason for failure apart from age) |
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