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STARLET
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STARLET.BTT
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2000-06-30
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STARLET Battery Recharging Date:06-05-1987 20:18:58
By LOU GENCO
The NEC Starlet has a tendency to drain its C-cells rapidly, even when
turned OFF. Several suggestions were given here to help reduce power
drain.
These suggestions require disconnecting one of the C-cells (with the little
red ribbon in the battery compartment), turning OFF the backup battery, or
some combination of the above. The problem is more apparent with NiCads
than with other battery types because of their lower amp-hr capacity.
--
I thought there might be a way to construct an internal recharging
circuit for the NiCads, but they require around 6 VDC, and the Starlet AC
adapter supplies 9 VDC. Also, loading the AC adapter with both a
recharging
task and the normal "working" load might cause eventual failure. Finally,
I
didn't want to mess up the nice wiring job NEC did inside the Starlet.
--
I eventually constructed an inexpensive portable external recharger that
recharges my GE NiCads at 110 ma, 1.25 v/cell. If you want to try it, you
will need the following parts (available at Radio Shack): Two double C-cell
battery holders; One 1N914 (or equivalent) diode; One coaxial connector (a
jack to fit the power supply plug); A 1/2 watt resistor (about 300 ohms); A
LED (optional)
--
Glue the C-cell holders back-to-back. Trim the power leads, and solder a
red wire from one holder to a black wire (wire the two holders in series).
Connect the remaining black (-) and red (+) wires as in the following
schematic:
--
+ |------------------|<--------|<-------/\/\/\/------------->
| D1 LED (and/or) R1 To sleeve
_|_
_
___
_
___ Battery holder
_
___
_ To post
- |---------------------------------------------------------->
=
The current limiting resistor (R1) should be chosen to allow 80-100 ma
charging current to the GE NiCads. Empirical determination with a
milliameter or VOM is fine. I replaced the resistor with a LED that
dropped
the current sufficiently, and allowed a positive visual signal when the
batteries were charging. (I had the LED in my junk box, and don't know the
specs).
--
I then encased the wires, diode and connector in potting compound (leaving
the LED peeking out), and affixed the whole thing to the top of the C-cell
holder. The unit is very light and small, fits in my travel case, and
appears to work well. Unfortunately, one must remove the C-cells from the
Starlet to recharge them; and simultaneous battery recharging and Starlet
usage is not possible.
--
So far, the set-up has worked, and hasn't blown either my batteries or
my AC converter; however, the usual disclaimers apply ... I am not
responsible for damages to your equipment if you try this thing.
--
I think the same circuit could be put on a piece of perfboard and connected
internally to the Starlet's power-in jack, so there might be a more
portable
option ... but I didn't want to overload the power supply. I'd appreciate
any notes from adventuresome folks who try the internal version. Trickle-
charging the NiCads while working on the Starlet would be a nice feature!
--
Lou Genco