Arduino Forum

Using Arduino => General Electronics => Topic started by: Synan on Jul 07, 2015, 09:34 pm

Title: Protecting the Computer's USB Port
Post by: Synan on Jul 07, 2015, 09:34 pm
I'm currently working with several younger kids, using the Arduino to teach programming. However, several have created short circuits, and now the connected USB port doesn't work (The Arudino is fine in a different port). Is there something I can put between the computer and the Arduino to protect from this. Something like a hub with serge protection, but I can't find anything like what I'm after.

There's to many to check every circuit and I know it's going to happen again, so I was wondering if anyone knew how to prevent it.

Thank you.
Title: Re: Protecting the Computer's USB Port
Post by: CrossRoads on Jul 07, 2015, 09:53 pm
A powered hub should be good.
This one for example specifically mentions overcurrent protection.
http://www.bestbuy.com/site/manhattan-mondohub-28-port-usb-hub-black/5486041.p?id=1218652749521&skuId=5486041 (http://www.bestbuy.com/site/manhattan-mondohub-28-port-usb-hub-black/5486041.p?id=1218652749521&skuId=5486041)
Title: Re: Protecting the Computer's USB Port
Post by: DVDdoug on Jul 07, 2015, 10:17 pm
A regular USB hub should protect against most mishaps.  A powered hub (one with its own wall-wart power supply) should isolate/protect the USB power.

The hub itself won't be protected but it's cheaper to replace a hub than to repair/replace a computer.

If it's a desktop computer you can use a USB PCI Card (http://www.monoprice.com/Product?p_id=48&catargetid=320013720000066114&cadevice=c&kpid=100048&gclid=CIWtmv7pycYCFVFefgodDsEP8A).   Then worst case, you'll have to replace a fried PCI card.


I think USB ports are supposed to be protected against power shorts (or excess current) but I'm not sure about something like a short between a data line and power, or if you apply 12V (or more) from an external source.
Title: Re: Protecting the Computer's USB Port
Post by: PrescottJoule on Jul 07, 2015, 10:21 pm
I have heard of/experienced a similar problem. If you want to turn it into a project (even possibly for the kids)  you can splice the wires and add in diodes to prevent the Arduino from sending current back to the port. The only downside is this prevents the Arduino from sending current back through the port and I'm not sure off the top of my head if you need this capability.
Title: Re: Protecting the Computer's USB Port
Post by: Synan on Jul 07, 2015, 10:48 pm
I'll try regular Hubs and hope that helps. The powered ones are a good idea, but I have nowhere to plug them in for power. I'll let you know what I find.
Title: Re: Protecting the Computer's USB Port
Post by: DrAzzy on Jul 08, 2015, 04:56 am
An unpowered hub offers little to no advantage.

The point of using the powered one is so that when they short it, it's not being supplied from the computer. If you use an unpowered hub, it won't make any difference unless it has more careful current limiting than your computer does (they typically don't)

Also, the port on your computer should work again if you wait a while and then reset the computer. I've seen this behavior many times - I think it trips the PTC, then the computer notices and shuts it down until next reboot (and the PTC can take some time to reset).
Title: Re: Protecting the Computer's USB Port
Post by: innovatorsguru on Jan 01, 2020, 08:16 pm
If you are new in electronics, return/reverse supply and overcurrent is the most common problem to damage your valuable laptop or computer while playing with arduino. Sometimes laptop ports are not isolated, it will increase the risk of motherboard damage. I also damaged my Asus laptop.

The best way to solve this problem is to use a USB Hub. I prefer an external power USB hub on the computer and usb c hub with my laptop. (https://thebest4you.co/usb-c-hub-for-macbook-pro-thunderbolt-3/)
Title: Re: Protecting the Computer's USB Port
Post by: Paul__B on Jan 02, 2020, 11:28 am
I should point out that most inexpensive and many expensive "powered" USB hubs simply connect all 5 V lines - that is, the incoming one from the PC and the outgoing ports - directly together with the regulated 5 V from the attached power supply.  :smiley-roll:
Title: Re: Protecting the Computer's USB Port
Post by: jonnyuno on Apr 09, 2020, 09:09 pm
I was working on an energy consumption prototype using non invasive tru-hole current transformer connected to a ESP8266 and my computer USB port. Disconnected one of the power lines to measure in series the current.. Took a phone call and got back to the project 1/2 hr later did not remember it was on  and tried to untangle one of the mains wires, the hot came loose and touched the voltage divider on the breadboard, bright blue spark and a pop !. Nuked right tru and blew the ESP8266, 3.1 USB ports and the motherboard.  :o

Replacement cost -> $300 for the parts !!!.  :smiley-money:

Fear for plugging anything into a USB - >lifetime... all estimated potential energy savings by project, down the drain  :smiley-cry:  :smiley-cry:
Title: Remarkable!
Post by: Paul__B on Apr 10, 2020, 01:12 pm
You mean to say you actually touched any part of the contraption while it was plugged into the mains?  :smiley-roll:

Or just as foolish - you walked away from an experimental apparatus while it was plugged into the mains?  :smiley-roll:

You have a habit of running with knives perhaps?  :smiley-eek:
Title: Re: Protecting the Computer's USB Port
Post by: MarkT on Apr 10, 2020, 03:26 pm
USB ports should be fully short circuit protected.  What they don't protect against is excess voltage on the power or data lines.