CA3046 replacemnt ?

[harry bissell]

No No NO!!! You glue an LM399 Temp Stabilized Zener Diode to the top of it,
with the plastic case removed. This has the heater and control circuit
attached to the top of the can (if I remember right). Clip off the zener
leads and just use the heater.

The resulting assembly MUST be shielded from air drafts or performance is
worse.

It would be better if you had a dual tranny in a TO46 can (small) that
would be a better mechanical fit for the LM399.

I've experimented trying to use this as a heater/sensor for the LM3046. It
didn't work well because of air drafts which made the heater in the 3046
drift... actually made the changes worse (dumb idea).

There was an old (now long lost) Idea for Design or Design Idea that used
the LM399 and a power tranny to be a temp control oven for a small crystal.

Use the LM399 its a winner.  :^) Harry

Paul Maddox wrote:

> MC,
>
> >If you look at the 3046 specs you can see that the bipolar parameters
> >indicate the transistors being crap. rbe and hfe @ large currents.
> >This will normaly make the expo converter going flat.
> >Extra circuitry can measure this and compensate via feedback loop,
> >but it would be better to use better npn right from the start.
> >
> >But since the 726 isn't any more we don't have that option.
> >
>
> Could use the LM394, and a stick a regulator on top, 7805 and give it a
> fixed load..
>
> Paul
>
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