Re: looking for good cordless phone sets

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Dave Houston" <nobody@xxxxxxxxxxxx> wrote in message
news:45dda753.147563890@xxxxxxxxxxxxxxxx
> "Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:
>
> >So how do the plug-in AA chargers avoid thermal monitoring or am I just
not
> >seeing those thermal detectors/protectors either?  I have *lots* of those
> >that I'm willing to cut open because I own a Nikon Coolpix battery hog
> >camera that only runs well on nearly-new NiMh's.  Lots of hi-cap NiMH
cells
> >came with free chargers so I have a box full.
>
> I'm not an expert but there are several methods for recharging NiMH cells.
> Google on "NiMH thermistor" and you'll find app notes from various chip
> manufacturers (e.g. Linear, Maxim) that provide details on their dedicated
> chips.
>
> When higher capacity NiMH cells appeared a few years ago there was a guy
on
> the RemoteCentral forums who proposed manufacturing higher capacity
battery
> packs for the Prontos. I researched it and pointed him to the resettable
> thermal fuses and thermistor he needed. (He had thought the thermistor in
> his original battery pack was a diode as it used the same DO-41 glass
case.)
> Interestingly, he found he needed to sell the battery packs for about $15.
>
> While I have a Sony BC-CS2A charger for the individual cells I use in my
> camera I've never taken it apart (it's not readily apparent how to open
it)
> to see which method it uses. It's limited to NiMH cells. There's a small
> aperature that might have a temperature sensor behind it. I found specs on
a
> different Sony NiMH charger (Sony BCG-34HRMD) that says it monitors
voltage
> and temperature.

I have a Sony BCG-34HC that I just took apart.  It had tamperproof slotted
screws securing the case.  If other manufacturers are any indicator, they've
probably gone to some sort of press-fit assembly method.  The tamperproof
screws tell me they don't want people going in there!

Anyway, on the circuit board, there are two components directly mid-center
of each of the two battery compartments labelled RT1 and RT2.  They are
glassy looking and pinch at the center like an hour glass.  Dead center on
the board is a yellow something labelled Y1 that looks like a ceramic
capacitor, at has markings that look like a tiny copyright symbol and the
lettering 8.00S.  Both components are far away from other circuitry.  I
suspect the RT1/2's are the thermal detectors/protectors.  Not sure what the
Y1 is doing there, but I assume it's an oscillator of some sort if they're
using standard board markings.

--
Bobby G.