Re: AppleWorks 3 + RamFactor + RamWorks 3 = what?

["Michael J. Mahon" <mjmahon@aol.com>]

Hugh Hood wrote:

> Anyway, here is something for you educated electronic types to elaborate on.
> While the RamFactor is a 5 volt card, the RamCharger battery backup unit
> uses an _8 volt_ battery. I remember back in the day having to look through
> several electronics catalogs to find one of that voltage. There were plenty
> at 6 volts and 12 volts, though.

Since battery voltage is not constant as it discharges, many battery
powered systems use a voltage regulator to create a stable power supply.
8v is about the lowest battery voltage that could be used with older
linear regulators to produce a stable 5v supply, since as it discharged
it would be expected to drop to a little over 6v.

A higher voltage battery could be used, but would increase the power
dissipation of the regulator--for example a 12v battery would more than
double the dissipation (12v-5v = 7v while 8v-5v = 3v, with dissipation
in the regulator proportional to voltage drop * constant current).

> Finally, here are a few of my observations on the RamFactor/RamCharger
> combo:
>
> (i) At its 5 megabyte maximum size, it was great having an instant-on Apple
> IIe with immediate access to all my main programs, including AppleWorks with
> tons of TimeOuts;
>
> (ii) The RamCharger battery backup was _not_ perfect. On occasion, it would
> lose everything, and I'd have to restore the entire 5 megs from floppy
> backups. It didn't happen often, but I'll bet it happened at least twice a
> year.  And I tried several different card/backup combinations, since we had
> multiple IIe's with that setup.
>
> BTW, I thought the suggestion posted about using a wall wart of some type
> plugged into a UPS would be a better solution than the RamCharger for the
> RamFactor. The UPS's I've used over the years have never let me down.

I'm guessing that even a couple of milliseconds interruption in battery
power to the RamCharger (because of any connector glitch) would cause
loss of data (because of loss of DRAM refresh), while a UPS and a wall
wart would be safe against all connection glitches *except* the actual
connection of the external supply to the RamCharger.  The typical
"barrel" connector used on wall warts is a very "noisy" connector if it
is even slightly rotated.

The cure for most such connector problems is a large capacitor soldered
to the RamCharger across the external power supply connector.

-michael

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