Hello to all,
I decided to make power supply for my OpAmp:
https://www.diyaudio.com/forums/analog-line-level/352814-hifi-preamp-lme49720-amplification-10x.html
Simple solution is to use L7815 and L7915. I checked data sheet, some schematics and this is the result. The stabilisers are having 100uV noise. Will the coils + caps reduce it well?
Thank you for your tips, tricks and thoughts!
Milan
I decided to make power supply for my OpAmp:
https://www.diyaudio.com/forums/analog-line-level/352814-hifi-preamp-lme49720-amplification-10x.html
Simple solution is to use L7815 and L7915. I checked data sheet, some schematics and this is the result. The stabilisers are having 100uV noise. Will the coils + caps reduce it well?
Thank you for your tips, tricks and thoughts!
Milan

100µV of noise is not an issue when most opamps have pretty high PSRR, say 100dB.
So now I know what is PSRR, thanks for pointing it out!

I wouldn't put L1 in the cct there it actually defeats the regulators.
If you feel the need for inductors they would be better on the inputs to the regulators.
If they are very low resistance they could be used on the outputs of the regulators.
If you feel the need for inductors they would be better on the inputs to the regulators.
If they are very low resistance they could be used on the outputs of the regulators.
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Re-check pinout on LM79xx. It is NOT same-as the LM78xx part.
1 is gnd 2 is input 3 is output.
I would better place T2 commom mode choke before power transformer (in primary circuit).
But if there will be RC snubbers across secondary windings then it is ok.
I'm not sure about 0.1mV AC noise from 7815/7915. It seems to me it is little more (plus newby hands).
But if there will be RC snubbers across secondary windings then it is ok.
I'm not sure about 0.1mV AC noise from 7815/7915. It seems to me it is little more (plus newby hands).
Re-check pinout on LM79xx. It is NOT same-as the LM78xx part.
I am very glad you pointed it! 😉
I would better place T2 commom mode choke before power transformer (in primary circuit).
But if there will be RC snubbers across secondary windings then it is ok.
I'm not sure about 0.1mV AC noise from 7815/7915. It seems to me it is little more (plus newby hands).
Perhaps I could have a two! before primary and after secondary.

I have to say I am little bit obsessive when it comes to noise.
The NJR has interesting low noise stabilizers, but not one for negative voltage at mouser.com
NJR Distributor | Mouser Europe
Nothing 🙂
I want to make more simple PSU. I like creating something new

Nothing 🙂
I want to make more simple PSU. I like creating something new![]()
OK, fair enough!
Jan
Double up on the caps and place either a 5-10R resistor, or a L between the existing and the new ones.
Double up on the caps and place either a 5-10R resistor, or a L between the existing and the new ones.
I like the idea about bigger caps. And where I should add resistor? In series for + and - rail?
Some people say LM317 & 337 are quieter, but usually I find 79xx series regulators or zeners with transistors inside appliances.
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