behind the scenes: Working on the B revision voltage standard

[JohnnyBerg]

But....

Mmmm, LTZ1000A, LTC2057, ADA4077, ect. i wil remove them from my stock parts.

Yeah .. I know. My first job was at a compagny that was in the Dutch AEX. So no LTZ1000A etc, because of the risk that production would stop, because there where no parts.

Not as important for a small compagny, but hey .. I'm brainwashed 

And my Agilent 3458A, i will throw him out of the window. 

Where do you live, and when are you throwing it out? 

[dadler]

Are these new ones available yet?

[JohnnyBerg]

are these new ones available yet?

They have been send to the pcb fab. a week ago. I'll expect them next week.
They have to be assembled then, and 1000 hrs aging.

Besides this reference, I also have a new low cost version coming, for testing/calibrating multimeters up to 4000 counts.
It will have a 5.000V output, a 1.000mA current source and 2 precision resistors

And a version with 10.0000V output from 1 9V battery.

Top of the range will be the "ovenized" version. It has a temperature controlled oven that keeps the reference chip at a constant temperature of 54°C

Each reference will come with a datasheet and a calibration sheet.
I will offer calibration service as well, and one time free calibration with this one.

At this moment I am working on gear to characterize the references. I build a 10.000x (80dB) preamp to measure noise. That was a challenge on his own
Result gives very nice pictures:

scale is 1.5 µV/div, I am quite happy with 5.88µV pp noise 

[Andreas]

Hello,

minimum measurement time for 1/f noise (0.1..10Hz) is 10 seconds. So your 200ms (per div?) scale limits lower bandwidth.

And it seems that there is no upper bandwidth limit (10 Hz) in your amplifier. There are much higher frequencies with large amplitude within the signal.

With best regards

Andreas

[JohnnyBerg]

minimum measurement time for 1/f noise (0.1..10Hz) is 10 seconds. So your 200ms (per div?) scale limits lower bandwidth.

And it seems that there is no upper bandwidth limit (10 Hz) in your amplifier. There are much higher frequencies with large amplitude within the signal.

I know .. 

I am still struggling with the filtering in the preamp. And I'm fighting with LTSpice to get the right values.
Here's the first stage:

[blackdog]

Hi JohnnyBerg,

What about presenting your schematic of the filter...

Let us help 

Kind regarts,
Bram

[JohnnyBerg]

I did a quick and dirty adjustment, now it's more to standard



I trying to lay an egg about some kind of noise reduction, but I think 7,26µV pp is not that bad. And just within spec of the REF5025.

I have carefully laid out the new board, and I'm hoping for better results. Grounding was a real pain in the ass!

[JohnnyBerg]

Got notice that the boards are ready and shipped!

As a service, I got a photo from the shipped boards. Looks exactly like the design 

[blackbird]

Nice pcb

Gegroet,

[JohnnyBerg]

I ordered 2 batches with PCB's. One express, and one with normal shipment.
And guess what?
I received the normal shipment, and the Express are still in transit.

Anyhow, I can start assembling the first 60 boards .. whow ..

[blackdog]

Hi JohnnyBerg,

Tomorrow i will wait next to my mailbox 

Kind regarts,
Blackdog

[JohnnyBerg]

Haha .. be patient.

Need to assemble and 1000 hr burn in. This is a bit of work .. who ..

[blackdog]

Hi JohnnyBerg,

No problem to burn one in overhere...
The choice is yours, I will be patient:-)

Nice looking circuitboards!

Kind regarts,
Bram