You
can make a single-battery discharger (make a set) with Radio Shack
parts: single AA holder, two 10 ohm 1/4 watt resistors, one diode
(IN4004, or most any OK). parallel the resistors by twisting the
ends together (along with one end of the diode, so it is in series
with the paired resistors. Solder the battery holder red wire to the
end of the resistor-diode string so that the diode arrow points away
from the red wire, and toward the black wire that is attached to
the other end of the string. Current flows through the diode and
resistor parallel pair until voltage goes down to .5 volt, then it
stops (overnight is good). Store the NiCads this way (not in the
discharger), and recharge them shortly before use (they self-discharge
over time, and are dead in about 3-mos of storage, even if fully charged
at the beginning). Normal NiCads are 500mah, but you can get 750's, and
even 1000's - just remember to charge them proportionately longer!
If you make a pack, and can figure out how to charge them, Radio Shack
High-output NiCad D cells are unusual, in that they are not C cells in
the larger case, as most D NiCads are - their output is very high, and
a pack of 4 or 5 of them is still quite light...