On Sep 24, 9:36 pm, clare at snyder.on.ca wrote:
Well, I've worked on an old battery set that, like a car radio of the
time, had a multivibrator to make the high plate voltages from a lower
battery voltage. IIRC the main battery was 12 volts. Most of the
"valves" or vacuum tubes ran on either 12 volts or six (2 in series)
but the rectifier has a 1 or 2 volt filament. It used an "ignition"
battery - one of those that used to run doorbells, fencers, and
battery ignitions on some stationary engines years ago.

Again, you're mixing things up. Rectifier tubes along with battery run
filaments just doesn't make sense. Like saying a gas cap for an
electric car. Or an extension cord for natural gas. You're mixing
metaphors!

2V filament tubes were designed for use with lead-acid cells. (Each
cell is 1.9 to 2.0V under discharge).

Ignition batteries (aka "Number 6 cells") are 1.5V. There are 1.5V
tubes used in portable radio equipment from the 30's/40's/50's,
because if you're carrying something around you do not want to carry
around a sloshy heavy lead-acid cell (this was of course the days
before sealed cells and gel-cells) but a lighter and more portable (if
less economical) carbon-zinc cell.

It was called
the "F"ilament battery. I think it was some sort of "farm" radio.

Lots of farm radios. All used 2V tubes and a single-lead-acid cell for
the filament, or 6V tubes and three lead acid cells in series for the
filament, or occasionally some weird funky combination.

Ah, ignition cells. I remember cutting them open with a hacksaw when I
was six years old to get the carbon rods out to try to make carbon arc
lamps with hacked up extension cords. They kinda sorta worked. I can't
believe I survived being six... or seven... ("geez, why did all my
solder disappear in a bright blue flash when I touched it with the
soldering iron") or eight... ("I'll just hold onto this antenna wire
as I climb around on the roof of the house") or nine... ("Wowza, maybe
I should let the power supply discharge before I touch the 800V B+")

The kids electricity books of the time actually *did* tell you to cut
open batteries to get the carbon rods. And I'm not particularly old!
(OK, the books were a little dated by the time I found them, and maybe
they weren't aimed at six year olds...)

Tim.