[time-nuts] HP5065A C-field current voltage mod

Charles Steinmetz csteinmetz at yandex.com
Fri Sep 4 12:27:15 UTC 2015


Perry wrote:

>OK, but why?  The temperature would be stable so the resistorsand 
>reference diode wouldn't drift.

There is a LOT more to making a good temperature-controlled 
environment than hacking together a DIY oven.  That may be fine for 
stability of tenths of a percent (10e-3), but when stability of 
10e-13 is at issue it doesn't pay to start with 50ppm parts and put 
them in a DIY oven.  You need to start with low-tempco parts.

>What about newer reference's IC's such as REF 102?
>I don't want to re-invent thewheel, just learn what is better.

You need to spend time researching the tolerance, noise, and tempcos 
of two- and three-terminal voltage references.  The manufacturers 
have on-line selection guides that allow you to sort products by any 
parameter you choose.  Most distributors do, too.  Or, look at a 
reference that has done much of it for you -- I suggest the new, 
third edition of The Art of Electronics, which has table after table 
of the very information you are looking for.

Best regards,

Charles






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