[GreenKeys] New 60ma current loop driver board design

[drlegendre .]

Gil said:

"I suppose we need to add some brass and tung-oiled cherry to the bot :)"

Just put some gears on it.. ;-)

Ed said:

"ok so what I experience is the port at it its limit then... it will not
get better.. Ok ! "

@John

So how is it then, that "dumb" USB-powered devices, such as these little
USB fans & lamps, can pull a current from the USB port without sending any
sort of request-to-enable signal? I was always under the impression the the
+5V was available at all times, on the port - 500mA for 2.0, (less) for 1.X
and (more) for newer 3.X specs?

And if the USB port doesn't supply constant power, how does the USB-powered
device make that request without a power source?

This is genuinely confusing.








On Fri, Oct 28, 2016 at 10:53 PM, Ed Sharpe Archivist for SMECC via
GreenKeys <greenkeys at mailman.qth.net> wrote:

> ok so what I experience is the port at it its limit then... it will not
> get better.. Ok ! Thanks Ed#
>
>
>
> In a message dated 10/28/2016 5:41:21 P.M. US Mountain Standard Time,
> radioengr at gmail.com writes:
>
> On 10/28/2016 10:54 AM, Ed Sharpe Archivist for SMECC via GreenKeys wrote:
> > OT  sortta  USB power related... .. how can I make my USB charge my cell
> > phone... faster.... seems computer is slowest form of charging...
> thx...ed#
>
> That's because it is the slowest form of charging. USB ports are current
> limited to 500mA (or 900mA for USB 3.0) to protect your computer.  The
> Apple 'USB' charger that I use provides 2000 mA.
>
> USB type C (USB-C) provides up to 100 watts on the connector...
>
> There is all kinds of USB.
>
> Rob.
>
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