Very low ref voltage

[SoothSayer]

A 1-volt reference is pretty useless for calibrating thermocouple
instrumentation.

The most accurate and stable voltage reference that I know of is only
about 500-700uV, which is inconvenient in some ways, but worth working
with in some cases.

Hey, I can now generate ratios of AC voltages on my bench with a
digitally selected resolution of 0.01ppm. Happy happy, joy joy.

A current shunt bearing the dissipation of being used like a little
'crystal oven', will constantly drop the same voltage and that can be a
good, low reference for your probe calibration session.

Likely not for his needs.

The noise floor simply becomes too 'everpresent'. It's like the cosmic
background. You keep trying to fix your circuit, when your reference
choice was the problem the whole time.

Gotta chill it all and put it in a cage, and make the room a cage as
well. Maybe then.

 

[Spehro Pefhany]

A current shunt bearing the dissipation of being used like a little
'crystal oven', will constantly drop the same voltage and that can be a
good, low reference for your probe calibration session.

Likely not for his needs.

The noise floor simply becomes too 'everpresent'. It's like the cosmic
background. You keep trying to fix your circuit, when your reference
choice was the problem the whole time.

So, about how much noise is there in a 10 ohm Thévenin-equivalent
divider, assuming, say, a 10Hz bandwidth and lab environment, relative
to the ~10uV resolution he wants?


Best regards,
Spehro Pefhany

 

[WoolyBully]

So, about how much noise is there in a 10 ohm Thévenin-equivalent
divider, assuming, say, a 10Hz bandwidth and lab environment, relative
to the ~10uV resolution he wants?


Best regards,
Spehro Pefhany

PARDon me, but ha ain't gonna get high resolution accurately and
consistently if he makes bad decisions about references.

 

[Fred Abse]

So, about how much noise is there in a 10 ohm Thévenin-equivalent
divider, assuming, say, a 10Hz bandwidth and lab environment, relative to
the ~10uV resolution he wants?

Thermal noise in a 1 Hz B/W is -174dBm, IIRC. Figure it from that.

 

[Fred Abse]

Thermal noise in a 1 Hz B/W is -174dBm, IIRC. Figure it from that.

That's at 290K, BTW

 

[Fred Abse]

Amazing they don't charge $100 for the part if they have to
test each one for 1000 seconds.

I assume that was tongue-in-cheek.

 

[Chieftain of the Carpet Crawlers]

I assume that was tongue-in-cheek.

Only perform bench experiments while keeping one hand behind your
back... :-0

Hand-in-pants.

1000 seconds is a long time. you could be accused of doing something
else.