I was wondering whether anyone here could help me on this one:
I have a battery pack of a mobile phone I'd like to replace for a set
of AA Ni-Cad batteries (reason: cheaper!). The mobile phone even has
the necessary mechanical/electrical pieces necessary for the mobile to
work with 4 AA batteries. The question is a couple of extra small
terminals the pack provides. I dismantled the pack and I found out
that one of them was connected to the pack (-) terminal, and the other
one was connected to a weird component, which is connected to the (-)
terminal. My question is: *what* weird component is that?
Some clues: It looks like a common 1N4148 diode: glass
capsule, two small copper-color cylinders, and something really small
in between. However, it is not a (common) diode! However, I suspected
it were a zenner pair (in series, symmetric polarity), and therefore I
tryed to measure the zenner voltage by connecting the component in
series with a 1K resistor, to a variable voltage power supply. In
fact, varying the voltage does not affect the voltage drop across the
component, remaining at 9.1V. At this time I was pretty sure it was a
zenner pair, maybe for protection or something like that.
However, the mobile does not charge the batteries (and does
not recognize their presence) if this component is removed! The mobile
charger has about 7V (open circuit), so I was expecting the supposedly
zenner pair to be "open". What I did was to measure the extra pin
voltage: without the component it measures about 2.5V, *with* the
component it drops to about 1.2V. So the component cannot be a zenner
pair. And this was the time I had the idea to post this message...
Thanks for any help/clues/(flames?) given!
Cheers,
--
*** Rodrigo Martins de Matos Ventura <yoda_at_isr.ist.utl.pt>
*** Web page: http://www.isr.ist.utl.pt/~yoda
*** Teaching Assistant and PhD Student at ISR:
*** Instituto de Sistemas e Robotica, Polo de Lisboa
*** Instituto Superior Tecnico, Lisboa, PORTUGAL
*** PGP fingerprint = 0119 AD13 9EEE 264A 3F10 31D3 89B3 C6C4 60C6 4585
Received on Fri Sep 01 2000 - 19:11:22 BST