Voltage reference opamp

[fryingpan]

Are there any cheap, yet relatively low-noise, low drift parts that can be used to buffer a voltage reference? I don't need "precision instrumentation" stability but of course, what's the best bang-for-buck part?

[amptramp]

If you are using a single op amp anywhere, change it to a dual and use the second half as a buffer.  Be sure to isolate any outputs from each other if you are using multiple outputs so you don't get feedback through Vref.  The op amp output usually cannot handle capacitance to ground so use an R-C filter if you need one.

[antonis]

https://www.ti.com/lit/eb/slyc147a/slyc147a.pdf?ts=1621961252717&ref_url=https%253A%252F%252Fwww.google.com%252F

[fryingpan]

If you are using a single op amp anywhere, change it to a dual and use the second half as a buffer.  Be sure to isolate any outputs from each other if you are using multiple outputs so you don't get feedback through Vref.  The op amp output usually cannot handle capacitance to ground so use an R-C filter if you need one.

The thing is that I'm out of free opamps in my preamp so I might as well select a part for the job.

[antonis]

The thing is that I'm out of free opamps in my preamp so I might as well select a part for the job.

For high presicion (not ultimate) you can use a 5.6 V Zener diode (due to almost negligible temperature voltage variation)  as voltage reference on non-inverting pin of a general purpose op-amp..
Depending on actual Vref, you can implement a pot between Zener & op-amp unity gain buffer input (for lower than 5.6V needed) or a pot between out & inverting input (for Vref higher than 5.6V)

A combination of the above should be a nasty overkill..
(although strongly recommended..)

[antonis]

actually it depends how you are defining precision

In comparison with a current consuming (due to low value resistors) voltage divider..

On the other hand, I'm not sure about Zener's superiority in relation to metal-film resistors temperature stability..

[antonis]

@fryingpan: Get yourself a Weston cell and earn peace of mind..

[diffeq]

TLE2426.

[amz-fx]

There is a good reference on virtual ground circuits at:

https://tangentsoft.net/elec/vgrounds.html

Best regards, Jack

[fryingpan]

What about a TLE2021? It has low offset, low drift drift, lowish noise and it's not the cheapest, but still quite cheap.

The application is for the circuit described at the bottom of this page:

http://www.lynx.net/~jc/transferCurvature-TubeSimulation.html

[ElectricDruid]

LT1013 is a good low offset low drift op-amp that gets widely used in the synth world for control voltage (CV) processing. If you've got a 1V/oct pitch CV, that's only 83.33mV per semitone, and humans can hear (roughly) a variation of 6 cents, which means anything over a few mV of error is unacceptable (5mV is definitely audible).
It's not too expensive either.

[duck_arse]

http://pdf.datasheetcatalog.com/datasheet/stmicroelectronics/4467.pdf

https://www.taydaelectronics.com/tl431acl-tl431-precision-shunt-regulator.html

[Rob Strand]

What about a TLE2021? It has low offset, low drift drift, lowish noise and it's not the cheapest, but still quite cheap.

The application is for the circuit described at the bottom of this page:

http://www.lynx.net/~jc/transferCurvature-TubeSimulation.html

For that circuit, noise OK, but drift?     TL07x would do it.