Re: [time-nuts] Hp10811 parts ref

[Didier Juges]

The actual offset value in this application is somewhat irrelevant.
Temperature stability of the offset voltage and bias current is. The 10811
met it's specs with the LM208 so there is no need to get a substantially
better part even though as you pointed out it is easy. My point was not to
use anything worse like what was suggested by the op.

Didier

On Wed, Sep 11, 2019, 3:48 PM Charles Steinmetz 
wrote:

> 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
>
>
>
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Re: [time-nuts] Hp10811 parts ref

[Charles Steinmetz]

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  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:




The LT1012 and OP97 are two more.  I've used both extensively, and
finally settled on the OP97 for this sort of application:




Best regards,

Charles



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Re: [time-nuts] Hp10811 parts ref

[Gregory Beat via time-nuts]

It has been 17 years since Steve Smith, G8LMX (Nottingham, UK) has taken 
time-nuts on his ‘Fantastic Voyage’ inside the dual oven of the HP 10811.
https://www.realhamradio.com/GPS-oven-journey.htm
I believe the challenge will be sourcing Quality Components properly 
characterized to operate at your designed temperature.
Surface Mount component advances, over the past 25 years, have reduced 
component size this reduction may introduce new issues to be addressed.

greg
==
Date: Fri, 13 Sep 2019
From: Club-Internet Clemgill 
To: 
Subject: Re: [time-nuts] HP 10811 parts ref

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. 

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Re: [time-nuts] Hp10811 parts ref

[Charles Steinmetz]

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  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:



The LT1012 and OP97 are two more.  I've used both extensively, and finally 
settled on the OP97 for this sort of application:



Best regards,

Charles



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Re: [time-nuts] Hp10811 parts ref

[Club-Internet Clemgill]

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  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:
> 
> 
> 
> The LT1012 and OP97 are two more.  I've used both extensively, and finally 
> settled on the OP97 for this sort of application:
> 
> 
> 
> Best regards,
> 
> Charles
> 
> 
> 
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> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
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Re: [time-nuts] Hp10811 parts ref

[Gerhard Hoffmann]

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





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Re: [time-nuts] Hp10811 parts ref

[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 ?

Best,
Gilles.

Envoyé de mon iPad

> Le 10 sept. 2019 à 20:29, "tim...@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-boun...@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.
> 
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Re: [time-nuts] Hp10811 parts ref

[tim...@timeok.it]

   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-boun...@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.

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[time-nuts] Hp10811 parts ref

[Gilles Clement]

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.

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