[volt-nuts] Traveling Standards

[Alan Scrimgeour]

Has anyone tried mounting these 'built in heater' references in a silvered 
high vacuum tube for thermal insulation?
It should save a lot of power and so make battery powering easier. In fact 
you may have to keep the leads short to stop it overheating just from the 
non-heater based dissipation of the reference.
Should sort out any variation due to humidity and atmospheric pressure too.

Scrim


----- Original Message ----- 
From: "Andreas Jahn" <Andreas_-_Jahn at t-online.de>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Friday, August 26, 2011 10:33 PM
Subject: Re: [volt-nuts] Traveling Standards


>
>>Any benefit in switching to a precision current source instead of the 
>>resistor?
>
> Hello Randy,
>
> the only benefit of a current source that I see is that you can use
> a lower supply voltage for the whole cirquit.
> I use currently 9.35V for the LM399s.
> So for me the use of a current source is mandatory.
> But with 15V I would not do that.
>
> With a current source instead of using one precision resistor
> you will have to use at least two.
> And you will have to find out how you can move the "hand adjustment" off
> your cirquit with some decoupling capacitors without generating 
> oscillations.
>
> With the LM399 and a resistor its easy. At the heater I use 100nF directly
> at the pins and 47uF not far away. At the output you will have to use 
> 100nF too.
>
> The resistor will not be sensitive for RF or common mode voltages.
> The voltage regulator should be decoupled too at input and output.
>
> With best regards
>
> Andreas
>
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