Not just semi-OT, Rodrigo!
Have you considered the possibility that the wierd component might be a
FUSE?
Proceed with caution.
Dick
----- Original Message -----
From: Rodrigo Ventura <yoda_at_isr.ist.utl.pt>
To: <classiccmp_at_classiccmp.org>
Cc: Tony Duell <ard_at_p850ug1.demon.co.uk>
Sent: Friday, September 01, 2000 6:11 PM
Subject: Ni-MH pack topology [semi-OT, I know, sorry...]
>
> 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 - 19:38:22 BST