Dear list, Looking forward to apply the oven configuration of the 10811 oven oscillator - that is working so well - could you please help me identifying the appropriate references for the active parts : Q7 and Q8 heating darligntons PNP Q4 driving transistor PNP U1 and U3 op amps From the schematic on fig 8-15 on page 64 of the HP manual. Thx very much, Gilles.

Gilles, what manual you refer? (Part number) Heating transistor are NPN.TO220 similar to TIP120 Driver is Q6 and NPN similar to 2N3904 U1 is LM2904N U3 is uA208M Luciano Da "time-nuts" time-nuts-bounces@lists.febo.com A time-nuts@lists.febo.com Cc Data Tue, 10 Sep 2019 17:54:17 +0200 Oggetto [time-nuts] Hp10811 parts ref Dear list, Looking forward to apply the oven configuration of the 10811 oven oscillator - that is working so well - could you please help me identifying the appropriate references for the active parts : Q7 and Q8 heating darligntons PNP Q4 driving transistor PNP U1 and U3 op amps From the schematic on fig 8-15 on page 64 of the HP manual. Thx very much, Gilles. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.

Luciano, References of the manual is the following: MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003 Dated August 1980. Thanks very much for your reply (indeed npn and Q6...!) Looking for a replacement for UA208 (obsolete) hard to find, as well as LM208 => would NTE928 or ECG928 be ok ? Best, Gilles. Envoyé de mon iPad > Le 10 sept. 2019 à 20:29, "timeok@timeok.it" <timeok@timeok.it> a écrit : > > > Gilles, > > what manual you refer? (Part number) > > Heating transistor are NPN.TO220 similar to TIP120 > > Driver is Q6 and NPN similar to 2N3904 > > U1 is LM2904N > > U3 is uA208M > > Luciano > > > Da "time-nuts" time-nuts-bounces@lists.febo.com > A time-nuts@lists.febo.com > Cc > Data Tue, 10 Sep 2019 17:54:17 +0200 > Oggetto [time-nuts] Hp10811 parts ref > Dear list, > Looking forward to apply the oven configuration of the 10811 oven oscillator - that is working so well - could you please help me identifying the appropriate references for the active parts : > Q7 and Q8 heating darligntons PNP > Q4 driving transistor PNP > U1 and U3 op amps > From the schematic on fig 8-15 on page 64 of the HP manual. > > Thx very much, > Gilles. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

LM108, 208, and 308s were the same pinout and I believe different quality specs. Attached the pdf. Seems the ICs are available in the $15 range. Sure they can be found cheaper. Regards Paul On Wed, Sep 11, 2019 at 9:21 AM Club Internet <clemgill@club-internet.fr> wrote: > Luciano, > References of the manual is the following: > MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003 > Dated August 1980. > > Thanks very much for your reply (indeed npn and Q6...!) > Looking for a replacement for UA208 (obsolete) hard to find, as well as > LM208 => would NTE928 or ECG928 be ok ? > > Best, > Gilles. > > Envoyé de mon iPad > > > Le 10 sept. 2019 à 20:29, "timeok@timeok.it" <timeok@timeok.it> a écrit > : > > > > > > Gilles, > > > > what manual you refer? (Part number) > > > > Heating transistor are NPN.TO220 similar to TIP120 > > > > Driver is Q6 and NPN similar to 2N3904 > > > > U1 is LM2904N > > > > U3 is uA208M > > > > Luciano > > > > > > Da "time-nuts" time-nuts-bounces@lists.febo.com > > A time-nuts@lists.febo.com > > Cc > > Data Tue, 10 Sep 2019 17:54:17 +0200 > > Oggetto [time-nuts] Hp10811 parts ref > > Dear list, > > Looking forward to apply the oven configuration of the 10811 oven > oscillator - that is working so well - could you please help me identifying > the appropriate references for the active parts : > > Q7 and Q8 heating darligntons PNP > > Q4 driving transistor PNP > > U1 and U3 op amps > > From the schematic on fig 8-15 on page 64 of the HP manual. > > > > Thx very much, > > Gilles. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

Am 11.09.19 um 08:33 schrieb Club Internet: > Luciano, > References of the manual is the following: > MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003 > Dated August 1980. > > Thanks very much for your reply (indeed npn and Q6...!) > Looking for a replacement for UA208 (obsolete) hard to find, as well as LM208 => would NTE928 or ECG928 be ok ? > You can also search for LM108 (premium version) and LM308. The LM308 is the base version, worse offset/temp. specc'ed etc, but may be good enough and from same production, just not cherry-picked. regards, Gerhard

The LM208 is a single op-amp with low offset (<3mV) and low bias current. The NTE928 is a dual op-amp with <7mV offset. You may be able to live with the offset at the cost of degraded performance but the pin-out is not compatible. Look for a single op-amp with very low offset. I am not near a computer right now but there must be a ton of those at Digikey. Didier KO4BB On Wed, Sep 11, 2019, 9:21 AM Club Internet <clemgill@club-internet.fr> wrote: > Luciano, > References of the manual is the following: > MANUAL PART NUMBER 10811-90002 Microfiche Part Number 10811-90003 > Dated August 1980. > > Thanks very much for your reply (indeed npn and Q6...!) > Looking for a replacement for UA208 (obsolete) hard to find, as well as > LM208 => would NTE928 or ECG928 be ok ? > > Best, > Gilles. > > Envoyé de mon iPad > > > Le 10 sept. 2019 à 20:29, "timeok@timeok.it" <timeok@timeok.it> a écrit > : > > > > > > Gilles, > > > > what manual you refer? (Part number) > > > > Heating transistor are NPN.TO220 similar to TIP120 > > > > Driver is Q6 and NPN similar to 2N3904 > > > > U1 is LM2904N > > > > U3 is uA208M > > > > Luciano > > > > > > Da "time-nuts" time-nuts-bounces@lists.febo.com > > A time-nuts@lists.febo.com > > Cc > > Data Tue, 10 Sep 2019 17:54:17 +0200 > > Oggetto [time-nuts] Hp10811 parts ref > > Dear list, > > Looking forward to apply the oven configuration of the 10811 oven > oscillator - that is working so well - could you please help me identifying > the appropriate references for the active parts : > > Q7 and Q8 heating darligntons PNP > > Q4 driving transistor PNP > > U1 and U3 op amps > > From the schematic on fig 8-15 on page 64 of the HP manual. > > > > Thx very much, > > Gilles. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

Didier wrote: > The LM208 is a single op-amp with low offset (<3mV) and low bias current. Even 3mV offset is verging on horrible for a "precision" opamp these days -- it's hard to find any respectable opamp that doesn't do lots better. The secret sauce of the LMx08 series is the super-beta input pair, which matches FET opamps for input current but also holds that low (room-temp) input current over the full temperature range (the input current of FET opamps generally rises by at least 10x to more than 1000x at warmer to hot temperatures). There is no need for extraordinary measures -- there are a number of more modern opamps specifically designed to upgrade LMx08 sockets. The OP77 is one: <http://pdf.datasheetcatalog.com/datasheet/analogdevices/206654345OP77_c.pdf> The LT1012 and OP97 are two more. I've used both extensively, and finally settled on the OP97 for this sort of application: <http://pdf.datasheetcatalog.com/datasheet/analogdevices/140679914OP97_d.pdf> Best regards, Charles

Charles, Thank you for this very useful information ! My plan is to « clone » as close as possible the initial 10811 design, as it is well proven. Except changing the crystal and possibly use modern components if they bring any improvement, and adapting the « mass » to the crystal format and manufacturing it through 3D printing. Did anybody tried something similar ? Best, Gilles. > Le 11 sept. 2019 à 22:05, Charles Steinmetz <csteinmetz@yandex.com> a écrit : > > Didier wrote: > >> The LM208 is a single op-amp with low offset (<3mV) and low bias current. > > Even 3mV offset is verging on horrible for a "precision" opamp these days -- it's hard to find any respectable opamp that doesn't do lots better. > > The secret sauce of the LMx08 series is the super-beta input pair, which matches FET opamps for input current but also holds that low (room-temp) input current over the full temperature range (the input current of FET opamps generally rises by at least 10x to more than 1000x at warmer to hot temperatures). > > There is no need for extraordinary measures -- there are a number of more modern opamps specifically designed to upgrade LMx08 sockets. The OP77 is one: > > <http://pdf.datasheetcatalog.com/datasheet/analogdevices/206654345OP77_c.pdf> > > The LT1012 and OP97 are two more. I've used both extensively, and finally settled on the OP97 for this sort of application: > > <http://pdf.datasheetcatalog.com/datasheet/analogdevices/140679914OP97_d.pdf> > > Best regards, > > Charles > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.

You are very welcome, Gilles. One point of clarification, and one additional note: I mentioned the LT1012 and OP97 together, then said I've settled on the OP97 without further comment. My choice had nothing to do with differences between these two parts. As far as I can tell from using them extensively, there are no differences -- for all I know, they could be made using identical masks. I chose the OP97 for supply-chain reasons that won't be relevant to anyone else. Looking at the 10811A/B schematic, the bridge sampling resistors (R22, R23) are 1Mohm. This is what accounts for choosing U3 with extremely low input bias current. Note that the LT1012/OP97 are roughly 1000 times better than the LMx08 in this respect (pA for the LT1012/OP97, nA for the LMx08) as well as input input offset voltage (mV for the LMx08, uV for the LT1012/OP97). One thing to note when replacing an LMx08 with an LT1012/OP97: Notice C19 (0.01uF from Pin 8 to Ground). This is an *overcompensation* capacitor, used to slow U3 down for lower noise and better transient response of the oven control loop. The LT1012/OP97 use *Pin 5* for overcompensation instead of Pin 8, so C19 should be connected from Pin 5 to Ground. Best regards, Charles On 9/13/2019 11:17 AM, Club-Internet Clemgill wrote: > Charles, > Thank you for this very useful information ! > My plan is to « clone » as close as possible the initial 10811 design, as it is well proven. > Except changing the crystal and possibly use modern components if they bring any improvement, and adapting the « mass » to the crystal format and manufacturing it through 3D printing. > Did anybody tried something similar ? > Best, > Gilles. > > > >> Le 11 sept. 2019 à 22:05, Charles Steinmetz <csteinmetz@yandex.com> a écrit : >> >> Didier wrote: >> >>> The LM208 is a single op-amp with low offset (<3mV) and low bias current. >> >> Even 3mV offset is verging on horrible for a "precision" opamp these days -- it's hard to find any respectable opamp that doesn't do lots better. >> >> The secret sauce of the LMx08 series is the super-beta input pair, which matches FET opamps for input current but also holds that low (room-temp) input current over the full temperature range (the input current of FET opamps generally rises by at least 10x to more than 1000x at warmer to hot temperatures). >> >> There is no need for extraordinary measures -- there are a number of more modern opamps specifically designed to upgrade LMx08 sockets. The OP77 is one: >> >> <http://pdf.datasheetcatalog.com/datasheet/analogdevices/206654345OP77_c.pdf> >> >> The LT1012 and OP97 are two more. I've used both extensively, and finally settled on the OP97 for this sort of application: >> >> <http://pdf.datasheetcatalog.com/datasheet/analogdevices/140679914OP97_d.pdf> >> >> Best regards, >> >> Charles >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >

One more LMx08 equivalent: the most obvious of all, the LT1008. I didn't think about it earlier because I assumed it would have been discontinued long ago. The LT1008 was designed specifically to upgrade LMx08 sockets, so it uses Pin 8 for overcompensation -- just like the LMx08. It is one generation older than the LT1012/OP97, so its DC specs are not quite as good as theirs' (but still *much* better than the LMx08). If I were choosing an opamp for this type of circuit today, with a new PC layout, I would use either the LT1012 or OP97. On the other hand, if I were fixing an HP10811 that had a defective U3, I'd use an LT1008 to avoid the need to re-route any traces. Best regards, Charles On 9/13/2019 6:04 PM, Charles Steinmetz wrote: > You are very welcome, Gilles. One point of clarification, and one > additional note: > > I mentioned the LT1012 and OP97 together, then said I've settled on the > OP97 without further comment. My choice had nothing to do with > differences between these two parts. As far as I can tell from using > them extensively, there are no differences -- for all I know, they could > be made using identical masks. I chose the OP97 for supply-chain > reasons that won't be relevant to anyone else. > > Looking at the 10811A/B schematic, the bridge sampling resistors (R22, > R23) are 1Mohm. This is what accounts for choosing U3 with extremely > low input bias current. Note that the LT1012/OP97 are roughly 1000 > times better than the LMx08 in this respect (pA for the LT1012/OP97, nA > for the LMx08) as well as input input offset voltage (mV for the LMx08, > uV for the LT1012/OP97). > > One thing to note when replacing an LMx08 with an LT1012/OP97: Notice > C19 (0.01uF from Pin 8 to Ground). This is an *overcompensation* > capacitor, used to slow U3 down for lower noise and better transient > response of the oven control loop. The LT1012/OP97 use *Pin 5* for > overcompensation instead of Pin 8, so C19 should be connected from Pin 5 > to Ground. > > Best regards, > > Charles > > > On 9/13/2019 11:17 AM, Club-Internet Clemgill wrote: >> Charles, >> Thank you for this very useful information ! >> My plan is to « clone » as close as possible the initial 10811 design, >> as it is well proven. >> Except changing the crystal and possibly use modern components if they >> bring any improvement, and adapting the « mass » to the crystal format >> and manufacturing it through 3D printing. >> Did anybody tried something similar ? >> Best, >> Gilles. >> >> >> >>> Le 11 sept. 2019 à 22:05, Charles Steinmetz <csteinmetz@yandex.com> a >>> écrit : >>> >>> Didier wrote: >>> >>>> The LM208 is a single op-amp with low offset (<3mV) and low bias >>>> current. >>> >>> Even 3mV offset is verging on horrible for a "precision" opamp these >>> days -- it's hard to find any respectable opamp that doesn't do lots >>> better. >>> >>> The secret sauce of the LMx08 series is the super-beta input pair, >>> which matches FET opamps for input current but also holds that low >>> (room-temp) input current over the full temperature range (the input >>> current of FET opamps generally rises by at least 10x to more than >>> 1000x at warmer to hot temperatures). >>> >>> There is no need for extraordinary measures -- there are a number of >>> more modern opamps specifically designed to upgrade LMx08 sockets. >>> The OP77 is one: >>> >>> <http://pdf.datasheetcatalog.com/datasheet/analogdevices/206654345OP77_c.pdf> >>> >>> >>> The LT1012 and OP97 are two more. I've used both extensively, and >>> finally settled on the OP97 for this sort of application: >>> >>> <http://pdf.datasheetcatalog.com/datasheet/analogdevices/140679914OP97_d.pdf> >>> >>> >>> Best regards, >>> >>> Charles >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there.