Don Foreman wrote:

On Tue, 21 Mar 2006 11:00:35 GMT, Gunner
wrote:


On Tue, 21 Mar 2006 09:50:34 GMT, "Karl Vorwerk"
wrote:


I had one when I was a kid but never had the fancy batteries for it.
Karl


All mine take D batteries, or self charge (dosimeters) using the
reader which uses..a D battery.

Gunner


Anybody know how these work? Is there a solid-state replacement for
a GM tube that works on low voltage?


I recall pocket dosimeters which had a thin conducting vane in them
which, when charged to a moderately high voltage got repelled from a
like charged stationary vane and sprang away from it. The dosimeter
module was transparent so you could see the vanes and was filled with a
gas similar to a geiger counter tube. When ionizing radiation made the
gas conductive the charge on the vanes was leaked off and they moved
closer together. How close they got was a measure of the total radiation
received since they'd been given a "full charge". (Thus, they were fail
safe if the charge leaked off through defective insulation or moisture.)

Back in the "Duck and cover" days, circa 1950, I remember building a
radiation monitor which was nothing more than an NE-51 neon bulb biased
at just below it's firing voltage. Radiation would make it discharge and
produce "clicks" in a pair of high impedance headphones connected to it.
I could set it off with an old wind up alarm clock which had a
"radium" dial and hands.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."