0V reference

[Fred Bear]

Can anyone help with designing a 0V reference?
FB

 

[Rene Tschaggelar]

Can anyone help with designing a 0V reference?

The intended accuracy and drift ?


Rene

 

[Fred Bear]

Thanks for the reply, Rene.
100% accuracy, 0% drift - It is critical that this is a 0.0000V reference.
FB

 

[Fred Bear]

I was told that a resistor to ground would do it, with a capacitor to 0V to
stabilise the voltage. What values of resistor and capacitor would you
recommend for 1 amp?
Fred

 

[Slurp]

I was told that a resistor to ground would do it, with a capacitor to 0V to
stabilise the voltage. What values of resistor and capacitor would you
recommend for 1 amp?
Fred

For your quoted 0.0000V reference at 1A the resistor needs to be <100 micro
ohms. -- but is in conflict with your required 100% accuracy.

Ideally you need a 1 * 10 ^(-(infinity -1)) femto ohm resistor and an
(infinity - 1) Farad capacitor.

BTW - Do you know what the capacitance is between two pinheads 1 light year
apart?

Slurp

 

[John_H]

Can anyone help with designing a 0V reference?
FB

0V relative to what?

 

[Spehro Pefhany]

Thanks for the reply, Rene.
100% accuracy, 0% drift - It is critical that this is a 0.0000V reference.
FB

0.0000V is trivial. 0.0000000 is more difficult.



Best regards,
Spehro Pefhany

 

[Joerg]

Hello Spehro,

0.0000V is trivial. 0.0000000 is more difficult.

Nah, replace the bolts with marine grade stainless and give it some more
torque

Regards, Joerg

 

[Robert Obermayer]

Nah, replace the bolts with marine grade stainless and give it some more
torque

Nah, stainless is a bad conductor, worse then steel.
Copper is what you need
If its a audio application, you will need a 101%
super-duper-ultra-OFC-OMG-WTCF-STFU plated bolt made from 50 year old
5-times refined silver from a certain mine in england that was processed
by a tibetian monk.Othwerise it will sound rough, cold, shady and dark.

 

[John Fields]

BTW - Do you know what the capacitance is between two pinheads 1 light year
apart?

 

[[email protected]]

Hello Spehro,


Nah, replace the bolts with marine grade stainless and give it some more
torque

Even marine-grade stainless steel is stainless by virtue of a thin and
cohernet layer of chromium oxide - I don't know which one - which has
an appreciable electrical resistance.

My conductivity meter stopped using stainless steel electrodes - a bad
idea that I'd inherited - at the point where I could prove that the
oxide film had an appreciable electrical resistance by changing that
resistance by exposing the film to 2% aqueous sodium hydroxide (whose
conductivity the meter had to monitor, along with that of the tap water
that washed it away).

 

[martin griffith]

Can anyone help with designing a 0V reference?
FB

would -273.16 degrees C help?


martin

 

[Spehro Pefhany]

Hello Spehro,


Nah, replace the bolts with marine grade stainless and give it some more
torque

Lots of unpleasant ways for 100nV to crop up..


Best regards,
Spehro Pefhany

 

[Michael A. Terrell]

Nah, stainless is a bad conductor, worse then steel.
Copper is what you need
If its a audio application, you will need a 101%
super-duper-ultra-OFC-OMG-WTCF-STFU plated bolt made from 50 year old
5-times refined silver from a certain mine in england that was processed
by a tibetian monk.Othwerise it will sound rough, cold, shady and dark.

You left out "Dank" ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Joerg]

Lots of unpleasant ways for 100nV to crop up..

Well, guys, this was meant as a joke...

Ok then, how 'bout a nice thick gold plating on everything? Of course
only gold mined from a particular mine here in California in 1850.

Regards, Joerg

 

[Rene Tschaggelar]

I was told that a resistor to ground would do it, with a capacitor to 0V to
stabilise the voltage. What values of resistor and capacitor would you
recommend for 1 amp?

A reference has never 1 amp. References just
supply the voltage, not power. Lookup
"supply" or "voltage regulator"

Rene

 

[Spehro Pefhany]

Well, guys, this was meant as a joke...
;-)

Ok then, how 'bout a nice thick gold plating on everything? Of course
only gold mined from a particular mine here in California in 1850.

How pure? Gold-copper doesn't have much thermocouple voltage, but a
couple tenths of a degree C would be enough to swamp 100nV. Galvanic
action might be possible too.

Of course the advantage of selling such a 'reference' to
unsophisticated customers would be that few would be able to test it
sufficiently accurately to complain.



Best regards,
Spehro Pefhany

 

[Pooh Bear]

A reference has never 1 amp. References just
supply the voltage, not power. Lookup
"supply" or "voltage regulator"

In that case the reference has appreciable resistance / impedance.

An ideal reference would have zero impedance and laugh at an Amp.

Graham

 

[Pooh Bear]

Can anyone help with designing a 0V reference?

You've been looking at some schematics that have 0Vref on them haven't you ? (
blushes )

Graham

 

[Rene Tschaggelar]

Rene Tschaggelar wrote:



In that case the reference has appreciable resistance / impedance.
An ideal reference would have zero impedance and laugh at an Amp.

An ideal reference yes, but actual references
only supply a few mA at close to zero ohms

Rene