On Sun, Aug 15, 2010 at 01:56:03PM -0700, Dick Moore wrote:
The 34401 uses a reference from the National LM199 family -- I suspect
they're selected in some first-order way to keep costs down. So using a few
LM399's, each with a little series resistance in parallel driving a
stable op-amp like an LT1150 chopper amp might be the best way to go. In my
experience, the LM399 aging curve tends to flatten out significantly after
about 10 hours of run time, so it doesn't take too long to get them pretty
stable, and then using two or three or four is cost effective and tends to
make a more stable system.
Do you think that controlling the temperature of LM399 by sensing his case
and using a PWM (or linear) control over the heater might improve his stability?
After all (ok, not quite) it's like to have an LTZ1000 that way...
The cost would be very different hovever and you may make batteries of 4
as you wrote.
Another thing to try at home.
Best regards,
Andrea Baldoni
On Sun, Aug 15, 2010 at 01:56:03PM -0700, Dick Moore wrote:
> The 34401 uses a reference from the National LM199 family -- I suspect
> they're selected in some first-order way to keep costs down. So using a few
> LM399's, each with a little series resistance in parallel driving a
> stable op-amp like an LT1150 chopper amp might be the best way to go. In my
> experience, the LM399 aging curve tends to flatten out significantly after
> about 10 hours of run time, so it doesn't take too long to get them pretty
> stable, and then using two or three or four is cost effective and tends to
> make a more stable system.
Do you think that controlling the temperature of LM399 by sensing his case
and using a PWM (or linear) control over the heater might improve his stability?
After all (ok, not quite) it's like to have an LTZ1000 that way...
The cost would be _very_ different hovever and you may make batteries of 4
as you wrote.
Another thing to try at home.
Best regards,
Andrea Baldoni
