[time-nuts] V standards

Richard Moore richiem at hughes.net
Sat Nov 29 20:58:53 UTC 2008


RE Brooke Clarke and Warren S 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




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