RE Brooke Clarke and Warren S posts: > Message: 6 > Date: Sat, 29 Nov 2008 08:24:43 -0800 > From: Brooke Clarke <[EMAIL PROTECTED]> > 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" <[EMAIL PROTECTED]> > 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 _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
