Electronics > Beginners
Negative version of LP2951 LDO
exe:
My friends, did we already established that regulation is actually required? A good opamp has quite good PSRR, so regulation might not be even needed.
Probably, regulation itself is not even needed. What needed is something to remove ripple. So, consider a capacitor multiplier as a regulator: https://en.wikipedia.org/wiki/Capacitance_multiplier . Or may be just a simple RC-filter (just don't make R too big).
MagicSmoker:
--- Quote from: exe on September 15, 2019, 09:12:34 am ---My friends, did we already established that regulation is actually required? A good opamp has quite good PSRR, so regulation might not be even needed.
Probably, regulation itself is not even needed. What needed is something to remove ripple. ...
--- End quote ---
Yep, see my post on the previous page...
--- Quote from: MagicSmoker on September 10, 2019, 02:54:22 pm ---...the regulation of the supplies doesn't need to be particularly good; just try to keep the ripple to a minimum.
--- End quote ---
...saying the exact same thing as you. 8)
ZeroResistance:
--- Quote from: Mp3 on September 14, 2019, 10:48:09 pm ---Hi, i know this might not be exactly what you want (i dont know exactly what you want) but i recently used this with a headphone amplifier which needed a bipolar power supply. It was cheap and does the job. I attached a female DC barrel plug extender to the Vin / GND and use a plain center positive 12v dc supply. Negative and positive voltage could be a little better matched (getting something like -14.75 and +14.9) but for the price it does the job.
https://www.amazon.com/gp/product/B0752CK8DK/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
I did not feel comfortable making a rail divider on this amp so i got that while i await delivery of a pcb to build a bipolar psu.
--- End quote ---
Nice find! I see that its a switched inductor topology. How did you filter out the noise that thing is putting out?
Currently I've opted for a switched capacitor charge pump for generating the -ve supply rail.
ZeroResistance:
--- Quote from: dmills on September 14, 2019, 11:09:27 pm ---
--- Quote from: ZeroResistance on September 14, 2019, 05:48:05 am ---I'm limited by my input voltage that is going to be 9V dc.
--- End quote ---
So why are you bothering with a voltage regulator at all?
9V (Or even +-9V, so 18V is well within the ratings of most sane audio opamps (+-15 to 18V is what most pro gear goes for), so adding a regulator will just cost you precious supply voltage and headroom, run off the raw rail (well decoupled!).
Regards, Dan.
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The reason for me going for regulators, what the adaptor which I was getting the supply from is a switching type, and my thinking was the regulators would attenuate the switching noise, and provide a cleaner source of power for the audio analog circuitry.
ZeroResistance:
--- Quote from: schmitt trigger on September 15, 2019, 12:01:49 am ---I have to ask,9 volts, from a battery?
If so, a linear voltage regulator is very wasteful.
And one of the primary reasons to use a regulator, ripple reduction, is not required with batteries.
--- End quote ---
No its not a battery, its a 9V adapter.
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