faunt@spar.UUCP (05/12/87)
I wish to use the AC adapter for my portable CD player to charge a set
of nicads in the battery case of the player since I want to use the
player on the aircraft while travelling without spending a fortune on
disposable batteries, but would rather not carry a separate charger.
I figure I have 9V (more or less) DC on a plug and an identical plug
connected to the 6 C cells in the battery case. All I need, I think,
is a current regulator between a pair of jacks. I'm considering using the
Radio Shack high capacity nicads, which suggest charging at 200 ma for
14 hours for a full charge. I've not measured the actual voltage
output of the AC adapter at a 200ma load, but I suspect it's at or
over 9V. I guess I could, perhaps, use a "universal" adapter that
might provide 12v for charging, but that would require making sure
that the switch was in the 9V state for operating the CD player, and
would be less than foolproof. The battery pack would actually be
8.4v, of course. It's been a while since I looked at this kind of
analog circuitry, so I'm not sure if this would work. Would one (or
more) of you nicad and analog circuit experts out there think about
this, and let me know if this makes sense, and point me at references
for this stuff (or send a design).
Thanks
...!ihnp4!{hplabs|decwrl}!spar!faunt faunt@spar-20.arpa