Author Topic: How apropriate would an LM308HZ be as a reference amplifier?  (Read 1457 times)

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Offline IconicPCBTopic starter

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Please comment
 

Offline Edwin G. Pettis

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Re: How apropriate would an LM308HZ be as a reference amplifier?
« Reply #1 on: June 28, 2018, 03:06:34 am »
The LM308A was used in the 731B among others, it isn't the lowest in noise but not bad, a LT1012 would be a good upgrade.
 

Offline IconicPCBTopic starter

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Re: How apropriate would an LM308HZ be as a reference amplifier?
« Reply #2 on: June 28, 2018, 03:21:37 am »
Thanks Edwin,

Have been looking to purchase a handfull.

LM308HZ NOS available in quantities of 10 pcs for a princely sum of AUD0.28

EDIT: each
« Last Edit: June 28, 2018, 03:23:15 am by IconicPCB »
 

Offline David Hess

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Re: How apropriate would an LM308HZ be as a reference amplifier?
« Reply #3 on: June 28, 2018, 03:26:25 pm »
Besides its unusually low input bias current, the 308 was the choice for precision during the 301A/741 era before dedicated precision amplifiers became available and inexpensive.  Sometimes users graded them for offset voltage drift or used them with an oven.

The LM308A was used in the 731B among others, it isn't the lowest in noise but not bad, a LT1012 would be a good upgrade.

And the LT1008 is a direct upgrade of the LM308.  The LT1012 and LT1097 are the same parts with some pinout and function differences.

The input bias current of the original LM308 (1.5nA typical) which lacks input bias current compensation is actually high enough that modern precision parts like the LT1001 and OP-07 would likely perform better due to lower noise and even better precision.  Just watch out for pinout differences in compensation and nulling.

 

Offline Gyro

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Re: How apropriate would an LM308HZ be as a reference amplifier?
« Reply #4 on: June 28, 2018, 03:38:53 pm »
There's probably something to be said for having those 308s in the nice hermetic 'H' packages, but that might be offset by the Thermal emf of the Kovar leads.
« Last Edit: June 28, 2018, 03:40:33 pm by Gyro »
Best Regards, Chris
 

Offline RobK_NL

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Re: How apropriate would an LM308HZ be as a reference amplifier?
« Reply #5 on: June 28, 2018, 06:42:05 pm »
If you could get a couple of LM121's to go with them ...
http://www.ti.com/lit/an/snoa655b/snoa655b.pdf
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