I want to make some good ( better then the ones I made) Vrefs. Better as in longtime stability and tempco. Just for fun. The ones I made upto now have a short time drift of 1 to 3 ppm, longtime ?? They are on for a month now, and begin to stabilize. I have the schematic from Warren that uses the 1n825, i can buy that from Farnell. I have a schematic that uses a LT1021B, also for sale at Farnell. But I have read about LM199/299/399 that is temperature controlled LTZ1000 that should be very good and VRE4100 but non of those sold by Farnell. What is the best option ? I am not a company so I can not order evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay acount because I do not like auctions and bidding. Fred PA4TIM

In my opinion LTZ1000A seems to be the best option (this is not only my opinion...), but suggestion of Warren using aged 1N825 is also very attractive, especialy when you can buy it by $1 piece. Look here: http://www.ebay.com/itm/1N825-6-2-Volt-Temperature-Comp-Reference-Diode-/270812844833?pt=LH_DefaultDomain_0&hash=item3f0db41321#ht_928wt_1061 I confess I bought 30 pcs from this source. 2011/9/30 Fred Schneider <pa4tim@gmail.com> > I want to make some good ( better then the ones I made) Vrefs. Better as in > longtime stability and tempco. Just for fun. > The ones I made upto now have a short time drift of 1 to 3 ppm, longtime ?? > They are on for a month now, and begin to stabilize. > I have the schematic from Warren that uses the 1n825, i can buy that from > Farnell. > I have a schematic that uses a LT1021B, also for sale at Farnell. > But I have read about LM199/299/399 that is temperature controlled > LTZ1000 that should be very good and VRE4100 but non of those sold by > Farnell. > What is the best option ? I am not a company so I can not order > evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay acount > because I do not like auctions and bidding. > > Fred PA4TIM > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- Zbyszek

Fred Schneider <pa4tim@gmail.com> writes: > I want to make some good ( better then the ones I made) Vrefs. Better as in longtime stability and tempco. Just for fun. > The ones I made upto now have a short time drift of 1 to 3 ppm, longtime ?? They are on for a month now, and begin to stabilize. > I have the schematic from Warren that uses the 1n825, i can buy that from Farnell. I am trying this too - it is not easy, the diodes I have are quite drifty and it is hard to identify the zero-TC current. I have 20 pieces that have had a few days burn-in so far. I need to work on my technique. > I have a schematic that uses a LT1021B, also for sale at Farnell. > But I have read about LM199/299/399 that is temperature controlled > LTZ1000 that should be very good and VRE4100 but non of those sold by > Farnell. > What is the best option ? I am not a company so I can not order > evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay > acount because I do not like auctions and bidding. You can buy LTZ1000 (and LM399) direct from the Linear web site. Gauranteed Genuine! I just bought two, arrived yesterday. :) I am a company, but I doubt that matters much in this case. -- John Devereux

Hello Fred, do you want to have a stable voltage (calibrator) or do you want to use this reference with an ADC for precise measurements? I tried many 5V-references for an 24Bit LTC2400 ADC. >From LT1027, LT1021 and LT1236 the LT1027 is the best. Similar performance I have found with a MAX6250A but my device seems to have some popcorn noise of around 1-2 ppm. I use a simple NTC temperature sensor to do a 3rd order polynomal compensation of the tempco of the reference. (see picture on 09.09.2011 in this list). I use LT1027CCN8-5 references and the stability after ageing is mainly determinded by relative humidity. (0,4 ppm / % rH) after having calculated the tempco out of the reading. Ageing is less than humidity influence during the last year. The references are now running since 3 years. To get humidity factor off I buyed 2 hermetically tight VRE3050AS from Digikey. But with my 2 devices have horrible noise (factor 3-5 over LT1027). Hysteresis I have measured on the first of the 2 VREs and found 4-5ppm compared to the LT1027 with about 1-2ppm. With best regards Andreas ----- Original Message ----- From: "Fred Schneider" <pa4tim@gmail.com> To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> Sent: Friday, September 30, 2011 9:49 AM Subject: [volt-nuts] Best Vref part ? >I want to make some good ( better then the ones I made) Vrefs. Better as in >longtime stability and tempco. Just for fun. > The ones I made upto now have a short time drift of 1 to 3 ppm, longtime > ?? They are on for a month now, and begin t ostabilize. > I have the schematic from Warren that uses the 1n825, i can buy that from > Farnell. > I have a schematic that uses a LT1021B, also for sale at Farnell. > But I have read about LM199/299/399 that is temperature controlled > LTZ1000 that should be very good and VRE4100 but non of those sold by > Farnell. > What is the best option ? I am not a company so I can not order > evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay acount > because I do not like auctions and bidding. > > Fred PA4TIM > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

I want it for two reaons, just make several for fun as experiment and indeed the best one as a ADC reference. Ok thanks, I will look if the sell the LT1027 too. But it is not heated, is a LM399 the only heated Vref ? Because for a LT1027 i have to make an oven. Fred PA4TIM Op 30 sep. 2011 om 23:50 heeft "Andreas Jahn" <Andreas_-_Jahn@t-online.de> het volgende geschreven: > Hello Fred, > > do you want to have a stable voltage (calibrator) or do you > want to use this reference with an ADC for precise measurements? > > I tried many 5V-references for an 24Bit LTC2400 ADC. > From LT1027, LT1021 and LT1236 the LT1027 is the best. > Similar performance I have found with a MAX6250A but > my device seems to have some popcorn noise of around 1-2 ppm. > > I use a simple NTC temperature sensor to do a 3rd order > polynomal compensation of the tempco of the reference. > (see picture on 09.09.2011 in this list). > > I use LT1027CCN8-5 references and the stability after ageing > is mainly determinded by relative humidity. (0,4 ppm / % rH) > after having calculated the tempco out of the reading. > Ageing is less than humidity influence during the last year. > The references are now running since 3 years. > > To get humidity factor off I buyed 2 hermetically tight > VRE3050AS from Digikey. But with my 2 devices > have horrible noise (factor 3-5 over LT1027). > Hysteresis I have measured on the first of the > 2 VREs and found 4-5ppm compared to > the LT1027 with about 1-2ppm. > > With best regards > > Andreas > > ----- Original Message ----- From: "Fred Schneider" <pa4tim@gmail.com> > To: "Discussion of precise voltage measurement" <volt-nuts@febo.com> > Sent: Friday, September 30, 2011 9:49 AM > Subject: [volt-nuts] Best Vref part ? > > >> I want to make some good ( better then the ones I made) Vrefs. Better as in longtime stability and tempco. Just for fun. >> The ones I made upto now have a short time drift of 1 to 3 ppm, longtime ?? They are on for a month now, and begin t ostabilize. >> I have the schematic from Warren that uses the 1n825, i can buy that from Farnell. >> I have a schematic that uses a LT1021B, also for sale at Farnell. >> But I have read about LM199/299/399 that is temperature controlled >> LTZ1000 that should be very good and VRE4100 but non of those sold by Farnell. >> What is the best option ? I am not a company so I can not order evereywhere. I can buy from R&S, Farnell and Conrad. I have no ebay acount because I do not like auctions and bidding. >> >> Fred PA4TIM >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

>I want it for two reaons, just make several for fun as experiment and >indeed the best one as a ADC reference. Ok thanks, I will look if the sell >the LT1027 too. But it is not heated, is a LM399 the only heated Vref ? >Because for a LT1027 i have to make an oven. > > Fred PA4TIM > Hello Fred, you are right: the LT1027 is not heated, so you will need some TC/temperature compensation. The only heated references that I know are - LM399 (used in most of the serious 6,5 Digit multimeters) - LTZ1000A (used in some 8,5 Digit multimeters) and the LT1019. But other guys have reported that the heater current on the LT1019 will shift the output voltage by about 1 mV so its not really usable. In the newer datasheets the heater is no longer specified. With best regards Andreas