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George wrote:
>John, Sanyo does not make a 4 or a 5 ma nicad. Perhaps they are 4.2 and
>7? I could use the 7's if that is what they are. I could also use the
>constant current source if the voltage is variable. Is it?
It's Sanyo's 12N-4000DRL and 12N-5000DRL packs (14.4 Volts)
in which they use their 4Ah and 5Ah D cells. My 95 catalog
lists 5000, 4400 and 4000 mAh D cells. Incidentally I can't
find a 4.2 Ah even though the 4000 is rated from 4Ah to max
4.6 Ah.
The AC based constant current chargers have been spoken for
but they *basically* work like this (I say basically because
AC can kill. I post this for entertainment purposes only!):
diode 2
AC ---- capacitor ----+----->!--------+
! pos
__!_ battery to
diode 1 / \ be charged.
! neg
AC--------------------+---------------+
The size of the capacitor and the voltage of the AC line
determine the charge rate (current). (The battery voltage
doesn't matter as long as it is small relative the AC voltage).
On 115 VAC the current will be about 50mA per 2uF.
For a 400mA charger I use 16 uF/ 350 VAC capacitors (surplus).
Such a charger weights nothing and takes very little room
but it's capable of 160 Volts on the output which can be
lethal. A refinement therefore would be to strap on a
voltage limiter across diode 1 but then heat management
rears it's ugly head and the danger pretty much remains
because _anything_ _can_ _fail_ _at_ _any_ _time_.
Always keep one hand deep in your pocket when dealing with high
voltages.
John
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