At 23:56 05/06/2004 +0100, Tony Duell wrote:
My dad had
(probably still has, knowing him) a big camera flash unit that
features one of these batteries. Big unit the size of a handbag with a
shoulder strap, with the accumulator in this, and flash gun on the end
of a
spiral cord. I was always fascinated with it as
a kid, so I guess that
places it earlier than the '70s...
These sort of units were quite common at one time (and often used
lead-acid 'wet cell' accumulators). Actually, I'd not be suprised if the
batteries were still available somewhere..
Sometimes there were 2 or 3 plastic balls of different densities inside.
They floated or sank depending on the density of the eletrolyte, which in
turn depended on the state of charge of the cell. Interesting idea.
Yep, his had the balls ... As a kid, I'd watch them when he had it on
charge to see if I could spot them moving! The battery was exposed on the
flash unit so you could monitor it's state as you used it.
Getting the HT for the 'electronic flash' tube
was something of an
entertainment before transistors (which took all the fun out of it, due
to the ease of making an oscillator that would run off a 6V battery).
Some manufacturers used a mechanical vibrator, like the one in a car
radio [1] to chop up the DC from a battery to feed it into a transformer.
Others used HV (250V or so) batteries. The Voigtlander Vitrona, one of
the first cameras to have built-in electronic flash, did this -- a
handle containing an HV battery plugged into the bottom of the cammera.
I remember, also as a kid, so mid to late 70's, pulling apart an old valve
radio I picked up at a jumble sale. Battery operated, with spaces for
about three different sort of huge batteries... I think one of those was
supposed to be an HV battery - I never came across one though.
[1] I am showing my age. This was how they got the HT
(B+) voltage for
valves (tubes) in car radios about 50 years ago...
-tony