I have an old Keithley 602 meter that uses a single Hg cell for the ohm
meter function. There are not many alternatives that matched the stability
of the mercury cells.
I don't see why they could not just put a core charge on the cells that
would make it desirable to recycle them. Or require a trade in to get a new
battery.
I also have an ultrasonic corona detector that used a multi cell battery
(8.4 volts) that I can't get any more.
Regards,
Tom
----- Original Message -----
From: "J. Forster" <j...@quikus.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Thursday, July 11, 2013 2:15 PM
Subject: Re: [time-nuts] Lead acid battery noise levels
Yeah! In spades. And there really are no good substitutes. I have a number
of instruments from ESI, GR and others that are pretty much doorstops w/o
them.
The solution the camera people use, the silver cells, are not available in
the larger sizes for instruments AFAIK.
-John
===============
But Hg batteries are So Moot! We're simply not allowed to have them or
make them. Nanny won't have them in the house.
I have a couple of Accutron clocks that would love to see a mercury cell.
ed breya
Second attempt at emailing again:
NiCd batteries should have the lowest noise for their size due to low
resistance, but if you look at ever-lower frequency, the Hg should be
superior since it has the most stable voltage with time and
temperature. Drift (including self-discharge) and temperature
variation response can appear as very low frequency noise independent
of the other noise sources and operating conditions. Hg batteries are
so stable that they were commonly used as voltage references or to
power small circuits without any additional regulation needed.
Ed
>Mike Feher wrote:
A long time ago, when I was concerned about a phase noise issue, I found
an
old NBS article. It was on measuring phase noise and included a
schematic of
an ultra-low noise amplifier. In that amplifier they used Mercury
batteries.
I also glanced at the referenced article, stating NiCad is the lowest
noise,
and, NiCads were available for a long time, yet they used Mercury.
Regards
- Mike
>
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Ghost in the Shell
Dr. Don Latham AJ7LL
Six Mile Systems LLP
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