WEIRD
PSRR is worse below 10V.
All the performance specs are at 10V. A data sheet is kind of like an advertisement. You show the product in its best light and hide any warts. What do want to bet that several parameters are worse at 8 volts maybe even noise.
What kind of input decoupling did you have for the regulator while running on batteries? Any chance that more RF noise was getting into the refence input while on batteries.
Batteries generate noise when current is pulled fron them. Maybe they were not queiter than your other supply voltage to the regulator at high frequencies where the PSRR is much worse than at DC.
PSRR is worse below 10V.
All the performance specs are at 10V. A data sheet is kind of like an advertisement. You show the product in its best light and hide any warts. What do want to bet that several parameters are worse at 8 volts maybe even noise.
What kind of input decoupling did you have for the regulator while running on batteries? Any chance that more RF noise was getting into the refence input while on batteries.
Batteries generate noise when current is pulled fron them. Maybe they were not queiter than your other supply voltage to the regulator at high frequencies where the PSRR is much worse than at DC.
Attachments
Re: Even powering a reference with a battery will yield noise
BTW my post was to demonstrate not the difference in noise percepted with the MAX6250 vs. LT1021-5 (or LM329) but the difference in <B>SOUND</B> (more analog like, less fatigueing, more smooth, plastic etc ....) I have no idea what specs in the datasheet are responsible for this. And also it was a big surprise the reference for the system has such a impact on the sound.
Yeah, yeah, put the whole thing in liquid nitrogen or perhaps liquid helium. Come on; keep it practical for home use, not laboratory or deep spacejackinnj said:
BTW my post was to demonstrate not the difference in noise percepted with the MAX6250 vs. LT1021-5 (or LM329) but the difference in <B>SOUND</B> (more analog like, less fatigueing, more smooth, plastic etc ....) I have no idea what specs in the datasheet are responsible for this. And also it was a big surprise the reference for the system has such a impact on the sound.
I have no idea what specs in the datasheet are responsible for this
That was the point of the technical disscussion to explore this in detail. Perhaps some more detail on how you baised the reference in normal use, as well as the filter and voltage regulator circuit would be helpful. I don't think everyone wants to pay thirty clams for a refence. Maybe the LT1027 sounds as good for much less money and even further tweaking of the circuit could yield even better sound. Power supplies have a profound influence on the sound of a circuit and we are very interested in your findings.
H.H.
That was the point of the technical disscussion to explore this in detail. Perhaps some more detail on how you baised the reference in normal use, as well as the filter and voltage regulator circuit would be helpful. I don't think everyone wants to pay thirty clams for a refence. Maybe the LT1027 sounds as good for much less money and even further tweaking of the circuit could yield even better sound. Power supplies have a profound influence on the sound of a circuit and we are very interested in your findings.
H.H.
LM385 & ICL8069 Voltage references
I bought some LM385 for a good price. Think it was 20 of them.
Still have some of them left.
It is 1.24v, but can be adjusted upto 5.3v.
How about ICL8069. A 1.2 v ref.
I see www.elfa.se have now gotten a TO92 version.
This is better priced than the TO52.
-------------------
BurrBrown, BB
have some references REF02
AnalogDevices, AD
has the REF43
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For a precision voltage regulator does not get any more precision, than what the reference has.
Very probably slightly worse.
When comparing noises (and such) in 2.5ref to a 5.0ref,
you should double the uV-noise for the 2.5ref.
Because the 2.5, will need twice as much gain
to achieve same output voltage.
Same goes of course, when comparing 1.25vref to a 10.0vref
The noise for 1.25 should be taken 8 times, to get a comparision.
-----------------------
halojoy - doing his math
I bought some LM385 for a good price. Think it was 20 of them.
Still have some of them left.
It is 1.24v, but can be adjusted upto 5.3v.
How about ICL8069. A 1.2 v ref.
I see www.elfa.se have now gotten a TO92 version.
This is better priced than the TO52.
-------------------
BurrBrown, BB
have some references REF02
AnalogDevices, AD
has the REF43
-------------------------------------------------------
For a precision voltage regulator does not get any more precision, than what the reference has.
Very probably slightly worse.
When comparing noises (and such) in 2.5ref to a 5.0ref,
you should double the uV-noise for the 2.5ref.
Because the 2.5, will need twice as much gain
to achieve same output voltage.
Same goes of course, when comparing 1.25vref to a 10.0vref
The noise for 1.25 should be taken 8 times, to get a comparision.
-----------------------
halojoy - doing his math
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