[Elecraft] [OT] dual-voltage electronics (charger units)

[Guy Olinger K2AV]

Dual-voltage is really an analog/transformer based concept.  When one
can get a smart switching power supply the size of a dime that time
slices the incoming voltage with just enough varying width to keep a
capacitor charged to a given voltage, the only real concern is making
sure the components are able to withstand 700-800 volts peak to peak
(2.8 times whatever) on the input side and and able to do the current
on the output side.  The more voltage on the input, the narrower the
conduction slice. Since the gate is either on or off, it doesn't have
partial conduction resistive loss, and doesn't have that heat load.

Doing high voltage to low voltage is really miniature these days
depending on the current draw.

I'd take it apart anyway  : >)

73, Guy

On Tue, Mar 23, 2010 at 10:33 AM, Phil Hystad <phystad at mac.com> wrote:
> An off-topic question.
>
> Most electronics these days have dual-voltage chargers.  For example, my iPhone, my B&N Nook, and my laptop are all dual voltage.  Thus, when in a 220 volt AC location, all you need to do is plug the unit in using an adapter common to that location (I was in Paris last week making use of these dual-voltage characteristics so this prompted the question).
>
> So, what is the technology of these dual-voltage chargers?  I am asking because they are getting pretty small.  The unit for my iPhone is just a little plastic wrapped container about 1 inch square.  My Nook charger is even smaller in that it is only about 5/8 inch thick by 1 1/4 inch long.
>
> Both of these units are USP interfaces so I figure 5 volts charging and I know the Nook charger delivers a little more then the 500 mA maximum of a typical USB.
>
> Are these transformer plus rectifier and voltage regulator or are they some kind of switcher, or maybe just a rectifier diode and voltage regulator.  They do heat up so there is something there absorbing a bit of energy.
>
> Maybe I need to cut one open but I am not wanting to do that if I can get the answer here.
>
> Thanks,
> 73, phil, K7PEH
>
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