AndrewT said:
They are in series with the film caps, the resistors to each rail and the caps tied to the ground plane.
Guess if I cook some type of scope, could may be able to measure which implimentation is the most stable. But since a lot of the ringing is in the megahertz range it may not hurt anything.
This is what this hobby is for me, a never ending quest to build the best. And it all starts with the power supply.
George
Re: Looks like it is missing a bypass cap
To "really" look at power supply performance you need to measure both phase and gain -- a good intro to this can be found on National Semiconductor's website, something like "Characterization of Low Dropout Regulators". LeCroy also has an apnote on characterizing power supply impedance. You shouldn't need a very high bandwidth scope for these purposes.
Audio Amateur, #1, 1983 had an article on characterizing power supply impedance -- but it required about $20,000 of HP equipment.
Panelhead said:
To "really" look at power supply performance you need to measure both phase and gain -- a good intro to this can be found on National Semiconductor's website, something like "Characterization of Low Dropout Regulators". LeCroy also has an apnote on characterizing power supply impedance. You shouldn't need a very high bandwidth scope for these purposes.
Audio Amateur, #1, 1983 had an article on characterizing power supply impedance -- but it required about $20,000 of HP equipment.
AndrewT said:
That particular chip gets close to the ad797 in terms of noise performance -- one very nice feature is that pin 1 in the SOIC version directly accesses the output -- meaning that the feedback resistor is on the same side of the chip as the input resistor.
I wonder if Walt Jung every stepped back from his statement (in "Picking Capacitors") that he wouldn't put a ceramic anywhere near an audio circuit -- in "Op Amp Applications Handbook" he recommends them on P87, but also suggests 10R inseries with the power supply pin to lower the Q of the resonant circuit formed by the cap, lead inductance etc.
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