Re: A dSLR's fastest shutter-speed is really no faster than its flash-sync speed.

On Mon, 09 Jul 2007 11:50:05 -0700, SMS wrote:

This demonstrates a complete lack of understanding of how USB power is
implemented. You get a guaranteed _minimum_ of 500mA _per port.

Wrong. That's just what the USB spec. assumes will be the
minimum. But there are USB ports that provide less. And you have
yet to back up your claim that most USB ports provide 1000mA. If
that was the case, there would be no need for USB devices, such as
Energizer's charger to drop down from drawing 500ma to only 100ma
when it has to share the USB with other devices. If every USB
socket is attached to a unique USB port, there would be no problem.
But that's not the case, and though you many not be able to tell by
looking at the connectors, they may be daisy-chained, sharing power
and bandwidth. Do you really think that a low powered USB mouse or
USB keyboard would need a dedicated USB port capable of providing at
least 500mA to only that one device?


In reality there is always some margin well over 500mA before shutdown.
They have do do this just for surge currents.

Chargers don't have small, temporary surges. They operate for
many hours, drawing current at a very uniform rate. If it was
otherwise, the faster charging Energizer USB charger wouldn't be
limited to being able to charge only two AA cells, and the Ultralast
charger that can charge up to 4 AA cells wouldn't charge so much
more slowly. Its charge rate, however, is still unknown. You only
speculated that it is slow, adding that the package provided few
details.


By the way, here's the data *** for the Energizer 2 cell USB charger
that was referred to:
"http://www.energizer.com/usbcharger/download/CHUSB_E_F_S.pdf";.
It does indeed state that to charge two 2500mAH batteries it will take 5 hours.
However _no where_ does it state what was claimed regarding multiple
devices using the USB ports reducing the charge current. If Eveready
ever actually made such a ridiculous statement then they realized their
mistake and withdrew it, but I highly doubt that they ever wrote
anything like that, it's probaly just another fabrication by the poster
in question. The only reduced current would _ever_ happen is if the
charger was plugged into an unpowered USB 1.1 hub that was shared with
other devices; every port on a notebook or desktop PC can supply 500mA
minimum. USB 2.0 hubs are always powered and can supply 500mA per port.


No need to foam at the mouth, dog. What you called a data ***
is NOT the data *** for Energizer's charger. It's the Duo
Charger's manual, printed in English, French and Spanish. What I
stated was copied from the Product Data*** (CHUSB.PDF), which I'll
paste below, again, since you didn't have the decency to quote it.
It was downloaded within the last 24 hours, so you can still
download it, and you have once more been proven to be a hot air
blowhard, since what I posted has *not* been withdrawn by Energizer,
nor was any part of it fabricated. Fabrication and wild speculation
remain your specialties, not mine.

You've also posted more of your bogus nonsense with the assumption
that the problem is in any way related to USB 1.1 ports or hubs.
Nowhere does Energizer have any caveats about using USB 1.1 vs USB
2.0, it only states that their charger can drop to a very slow
charge rate if other USB devices are used. Is Energizer fabricating
a non-existent possibility? Here's my quote, that you referred to :

Energizer also makes a USB charger that's powered through the USB
port, and it probably charges much faster than the Ultralast, taking
only about 5 hours to charge 2,500mAh NiMH cells. But because it's
limited to the USB power supply, it can only charge one or two NiMH
cells at a time. Energizer's Product Data*** also warns that :

Multiple devices using the USB ports will greatly reduce charge
current to a slow charge. The AC adapter will always provide a
quick charge current.

To provide greater context, here's the more complete quote, again,
copied from the Duo Charger (CHUSB) Product Data*** :

Product Detail:
Designation: Duo Charger
Color: Black and Green, Blue or Magenta
Capabilities: 1 to 2 "AA" Note: when charging a single
1 to 2 "AAA" battery, use bay (1) only
Charging Current: USB Quick Charge 1-2 "AA-AAA" 550mA
USB Slow Charge 1-2 "AA-AAA" 125mA
NOTE: Quick charge current depends on the power
output of the computer USB. Multiple devices using
the USB ports will greatly reduce charge current to a
slow charge. The AC adapter will always provide a
quick charge current.

Trickle Charge: 20-60mA
Shutoff Mechanism: Delta V, Max Voltage and Timer Control
Delta V Detection 10mV per cell
Max Voltage 1.65V per cell
Max Timer Control Quick Charge "AA" 5.5 hours
Quick Charge "AAA" 1.5 hours
Slow Charge "AA" No Timer
Slow Charge "AAA" 10 hours
Charger Input: Quick Charge DC 5V 500mA
Slow Charge DC 5V 100mA
AC Adapter Input: 100-240V AC 50/60Hz 150mA
AC Adapter Output: DC 5V, 500mA
Weight (charger): 68 grams (2.4 oz.)
Dimensions (mm): 33 x 101 x 40 (H x L x W)
Safety Features: Delta V Charging Cut Off
Max Voltage Shutoff
Reverse Polarity Protection
Primary Battery Detection

Your posts often contain some minor pieces of misinformation or
deception, but this post of yours went *way* beyond merely pathetic.


I humbly suggest that you be more discerning in the future when
looking for someone with a scientific and technical background.

You? Humble? <g>

(I couldn't honestly type "Don't make me laugh.")

.