Hi,
Can i also play?
This is a portable reference i am designing, is uses a LM399.
I've done my best to keep the noise low and the current to the heater as low as possible.
Therefore, I use three 9V batteries, it gives me a lower heater current and longer live of the batteries.
Only 2 euros each, for alkaline here in the Netherlands.
The corner of the filter is about 1 a 1,5 Hz, this is low enough to filter out most of the noise.
If you are calibrating a digital multimeter, choose the longest integration time, 1 to 2 seconds.
There are also elements for the protection of the circuit on the output circuit.
I now own a calibrated Agilent 3458a, later i wil show a short term plot of the portable reference.
Shoot at it!
Kind regarts,
Blackdog