[time-nuts] Lead acid battery noise levels

[Bob Camp]

Hi

Ok, let's put some numbers on this:

1) The original post was about an OCXO (as opposed to a VCXO or VCO).
2) One would *assume* that only stable OCXO's are of interest to this group… :)….
3) Single ovens with 1x10^-9 per percent delta V are "not so stable", parts with 1x10^-11 per percent are quite possible. 
4) Supply voltages around 12 volts are pretty common
5) < 1.0x10^-13 at one second is doing pretty good on an OCXO

From that one can do some math.

One percent of 12 volts is 120 mv. 
One mv will be < 1.0x10^-11 on the "not so stable" OCXO and < 1.0X10^-14 on the stable one.

Is your supply good to 1 mv? Most of my lab supplies are. If so, that's probably good enough. If you have a poor supply, many common 3 terminal regulators are amazingly stable under normal lab conditions. I *know* that my batteries aren't stable to 1 mv over days with an OCXO pulling current off of them. Regulator changes voltage with temperature? So do batteries and OCXO's and lab supplies. 

Bob

On Jul 11, 2013, at 3:39 PM, Max Robinson <max at maxsmusicplace.com> wrote:

> Ed.  I for one am getting all of your messages.  Perhaps your spam filter is taking them out for some reason.
> 
> Regards.
> 
> Max.  K 4 O DS.
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> ----- Original Message ----- From: "ed breya" <eb at telight.com>
> To: <time-nuts at febo.com>
> Sent: Thursday, July 11, 2013 11:39 AM
> Subject: Re: [time-nuts] Lead acid battery noise levels
> 
> 
>> Third 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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