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Making the Designs to power itself through the USB — Parallax Forums

Making the Designs to power itself through the USB

ejwongejwong Posts: 21
edited 2011-09-17 23:04 in General Discussion
as the title says, having an external powersupply is a little bit costy, so is it possible to supply the parallax kits through the USB input?

Edit: okay i`ve been reading through the forums and saw some threads about hacking the USB to power the kits, well why not just include a jumper to automatically do it? is the extra two pins such a costy way to implement it?

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-08-25 19:28
    The USB power situation isn't designed for use as a "bench supply".
    A jumper or a switch could be placed, include a picofuse (which could be jumpered, too), etc., that's not rocket science.
    Flip that switch, if you can take the hit; move that jumper, if you're big enough.
    The trouble is that someone will do something boneheaded and take his USB down URL="http://www.youtube.com/watch?v=r0yXqU-w9U0"]as in ''He's dead, Jim''[/URL and then great wailing and gnashing of teeth will ensue.
    ("I did everything right, and nothing wrong, and now my USB is dead! Dead. Do you hear me?! Dead! My hands are clean, it's your fault! Boo hoo hoo...)
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-09-11 08:03
    Here's an informative article on USB Power.
  • BeanBean Posts: 8,129
    edited 2011-09-12 10:31
    On my USB powered propeller mini development board, I used a PTC resettable fuse because I did exactly that (blew up a USB port). After using the PTC I could create a dead short without harming the USB port.

    Bean
  • john_sjohn_s Posts: 369
    edited 2011-09-17 23:04
    Interesting observations and a question - there must be a reason that stops pc manufacturers (other than $) to NOT implement a PTC fuse on every usb port?
    I successfully blew up an usb chip on dell's mobo when re-connecting my usb powered camera made by ms. Quite the same damage was done to another mobo years ago when connecting logitech b/w cam that was stealing power from keyboard's connector.

    I guess they do not care to make any kind of built-in protection into peripheral devices or motherboards at all. User beware or plain poor engineering?
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