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Re: [Electronics_101] Re: Building a Quad/Octo/Dozen USB 1amp charger

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  • Charles Carroll
    ... Yeah you have the brains for sure. Me I will be working off templates other smart people design with small tweaks standing on shoulders of giants and all.
    Message 1 of 33 , Jan 1, 2012
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      On Sun, Jan 1, 2012 at 4:51 PM, Stefan Trethan <stefan_trethan@...>wrote:

      > **
      > I would not want to be the engineer who has to actually make this.
      > Wait... I am the engineer who would actually have to design this, damn!
      Yeah you have the brains for sure. Me I will be working off templates other
      smart people design with small tweaks standing on shoulders of giants and

      > It is tricky enough to get a power supply to make a narrow range of
      > voltages and currents while fulfilling all the requirements (such as
      > LOW COST, efficiency, LOW COST, standby power consumption, LOW COST,
      > safety, LOW COST, emc, LOW COST, oh, and CHEAP!).

      Well once we made the MegaDC power box i.e. say 36v and we standardized it
      and standardized the smart plug where all DC devices (from phone to laptop
      to tablet to powered speakers, etc.) then cheap comes. Cheap comes when you
      can manufacture millions and billions not thousands. Standardization helps
      achieve cheapness. Look at how cheap PCs and Laptops became compared to 2
      decades ago and Flat Monitors and Printers. WinTel standardization helped
      because high volume sales leads to cheap manufacturing and of course
      manufacturing by robots (and people in very poor countries with low wages,
      unsafe conditions, and anti-environmental policies/non policies is the ugly
      side of cheap hardware).

      > Making several voltages "on demand" is not a reasonable idea. What
      > could work is using a relatively high voltage, say 48V like used for
      > power over ethernet (yet another grand idea abusing data connectors).
      > It could be transmitted over short distances using reasonably thin
      > wires, with DC/DC converters on the device end.
      Why are smart plugs such a bad idea they could make the request for n volts
      at say n amps and the BIG DC BOX at panel box could send what they need.
      Such a smart power supply capable of putting out dozens of different volts
      and currents would need a very good design but could get cheap when the
      power companies, best buy, Walmart offered them to just plug into a wall or
      breaker panel. And then we would have one bulky smart power supply under a
      table, in the basement and no dozens of transformers around the house. No
      need to use Ethernet one could make a new "end' for some Romex style cable
      could be called DCRomex*

      They say all progress is made by unreasonable men a Smart DC box that
      supplied various power to various devices with not transformers at the
      device level would be hailed by consumers as the be all end all. install
      one oversized smart DC power box and eliminate dozens of transformers and
      trips to store to replace broken or missing ones. One DC smart power supply
      and plugs to rule them all. My QuadFast charger would just use a smart plug
      and ask for 5v 24amp (2 amps per each plug) max and the DC box would
      provide it.

      * AC Romex should have had standardized ends rather than forcing splices
      years ago from my viewpoint. Some kind of ends that the 2 wires could not
      be plugged in wrong to outlets and fans, etc. Think the kind of clever
      idiot proof connectors that could not be put on the wrong side ever. A lot
      of electricians would not be charging people a lot to put in a new outlet
      if such romex ends existed and outlets and ceiling fans were installable
      safely by laymen without having to read manuals instead they could focus on
      reading Electrical codes and inspectors would be getting a ton more
      business and electricians would focus on inspecting whether something was
      to code rather than charging to put in ceiling fans, smoke detectors,
      additional convenience outlets, etc.

      [Non-text portions of this message have been removed]
    • DJ Delorie
      ... Any device that looks for that, has negotiated for the power, and is a smart device in my book. In theory, if it doesn t see the short, it should choose
      Message 33 of 33 , Jan 4, 2012
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        I wrote:
        >> Smart devices use transistors (or other circuits) to keep the
        >> high-current parts of the circuit disconnected until the power
        >> requirements are negotiated.

        jong kung <jongkung01@...> writes:
        > Didn't ST post that if the middle two connectors (data wires) are
        > shorted, the USB power is known basically a dumb charger and no
        > negotiations will happen ?

        Any device that looks for that, has "negotiated" for the power, and is a
        smart device in my book. In theory, if it doesn't see the short, it
        should choose not to draw as much power since it doesn't know that the
        thing it's plugged in to is a "dumb charger".
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