[time-nuts] V standards

[WarrenS]

First off, it is good to remember we are mixing what can be done 
on the cheap at home with what can be done at Fluke with their resources.

Most of what that Geller's patent does is just provides a 
 source for some slightly less than near perfect parts 
all in one neat little package for a couple of dollars to 
those of us that don't already have them setting around.
It does NOT give better performance than a 
Perfect amp and perfect match resistors,

Second off you are not going to filter random "flicker noise with a 
RC, which is what limits the short term accuracy of most references.


WarrenS
*****************
RE Brooke Clarke and Warren SO posts:

> Message: 6
> Date: Sat, 29 Nov 2008 08:24:43 -0800
> From: Brooke Clarke <brooke at pacific.net>
> Subject: Re: [time-nuts] Voltage Standards
>
> Hi:
> Geller's patent 7382179 Voltage reference with enhanced stability  
> explains how
> he combines the AD587 voltage reference with the LM399 voltage  
> reference to
> obtain improved temperature stability.  The method can be used with  
> the LT1000.
> http://www.google.com/patents?id=v0GqAAAAEBAJ&dq=7382179
>
> Brooke Clarke
> http://www.prc68.com
> ------------------------------

Brooke, I read the patent with interest, and I cannot see how using  
the LM399 and AD587 together represents an improvement over just  
using a 399 and a chopper amp for the needed gain to get 10V (or  
whatever) out. Geller's external adjustment R chain will suffer  
tempco problems similar to a set of Rs used to gain-set the chopper,  
and making the chopper an integrator with a long TC should help with  
the 399's noise. Can anyone see where a further tempco improvement  
from using the AD587might come from?

> Message: 9
> Date: Sat, 29 Nov 2008 12:05:43 -0800
> From: "WarrenS" <warrensjmail-one at yahoo.com>
> Subject: Re: [time-nuts] Voltage standards
> .....clip
> The TC correction circuit I use is just two standard parts.
> A100K pot is placed between an added transistor's collector
> and ground with the pot's wiper going to the transitor's base.
> What that does when current is applied to the transistor is to make
> the collector voltage vary with temperature by an adjustable amount.
> This temperature sensitive voltage is then added with the trim voltage
> to the reference's trim input to cancel the 1st order temperature  
> drift.
> The results I got was a settable 4 degF wide ZERO TC,
> turnover point at any desired room temperature.
> The added parts fit on the small Geller's PCB.
> ...../clip
> WarrenS
> **************

Thanks for the input Warren -- I think your mod explanation is pretty  
clear -- and nice.

Dick Moore