The RefAmp & General Stuff on Temperature Compensated Avalanche / Zener Diodes

[quantumvolt]

Open thread to supplement the LTZ1000 and LM399 threads.

I thought it would be nice to start with some pictures from the 1960-70s.


The RefAmp topology:




HP RefAmp - used at least as early as 1963:






Fluke RefAmp - first use by Fluke seems to be in 1971:




For more modern canned devices there are plenty of pictures on the web.


Two schematics showing the basic configuration for an adjustable amplified voltage reference based on the RefAmp:

HP 3450A:




Fluke 731A:

[wiss]

The ref-amp was used in the fluke 341a as well, dating to -68 or -69 (?)

[quantumvolt]

The ref-amp was used in the fluke 341a as well, dating to -68 or -69 (?)

That is correct! I did not know. And the reference schematic is all discrete components and very similar to the HP 3450A over (the refamp as reference and error amplifier, a high gain differential amplifier, and a series regulator element).

Thank you very much for this info. I am sorry I didn't see it before now.

Since the manual I found on the web for Fluke 341A is dated 1969, and the Fluke 731A manual (I have) is from 1971, I know that Fluke had experience making voltage reference boxes before the (somewhat helpless) 731A.

Fluke 341A (attachment below):