You might find this interesting:
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
https://www.diyaudio.com/community/...-checked-to-see-its-stable-havent-you.191389/
Hi,
just read the whole thread. This gives another picture than reading it over time, while it developed. You may not like my conclusions. For me there are some points that would make me stop instantly and fix things, before I try anything else.
First, if your 15V regulators do not put out 15V at the positive and negative side, you need not to continue. A few fractions of a volt are acceptable, but not one Volt! So your regulator is defective and probably putting out all kinds of nonsense. Which makes anything else you do with it the same: Nonsense.
Fix the power supply, transformers can be broken, rectifiers leak and many parts you use are most suspect. If not fake, pulled from old boards and ages old.
All your (proven, thousands sold) new bought boards fail if you try them. Ask yourself what do you add from your side that may be the cause of failing. Do not only blame all of these products to be constructed wrong. Because that is what you did.
Next, you seem to wire the potentiometers away from the basic PCB. This is always a problem, screened wire or not.
Your surprising results make me think you do not know that there are linear and logarithmic pot's around, which have to be used differently? Would explain a lot.
Learn to use your tools. Your scope has so many functions, there is one correct setting and a thousand that may show funny results. A scope should tell you in seconds what problems your power supply has or at which point of your circuit the oscillations start. Only if you know how to use it, of course!
It seems to me you jump from one point to the next without understanding what you do. Like pulling out the caps placed the integrated circuits, which need to be there and never can do any harm. So you have not understood what they do.
You ask for advice but only follow your own, unfounded, spontaneous ideas. That is playing around. Working systematically means going from the start to the end, not jumping around.
I know that in may countries "trying until it half way works" is the way to go and even called "a job" or "profession". 3 people standing around a broken thing, discussing, poking and waiting for the magic idea that will fix anything.
Consider this system not to be the best way for fault finding. If you stick to this system, you probably build in new faults while you try to fix the primary ones. Even if anyone around you may work that way.
If you go a,b,c,d and so on with a problem, you can not miss a fault. Anything else is just lottery.
If you have read until here without getting emotional, congratulations! You may start all over and find out how easy to do electronics can be (if they are that simple as yours) and you follow the rules and laws of physic. If not, I'm sorry.
Good luck!
just read the whole thread. This gives another picture than reading it over time, while it developed. You may not like my conclusions. For me there are some points that would make me stop instantly and fix things, before I try anything else.
First, if your 15V regulators do not put out 15V at the positive and negative side, you need not to continue. A few fractions of a volt are acceptable, but not one Volt! So your regulator is defective and probably putting out all kinds of nonsense. Which makes anything else you do with it the same: Nonsense.
Fix the power supply, transformers can be broken, rectifiers leak and many parts you use are most suspect. If not fake, pulled from old boards and ages old.
All your (proven, thousands sold) new bought boards fail if you try them. Ask yourself what do you add from your side that may be the cause of failing. Do not only blame all of these products to be constructed wrong. Because that is what you did.
Next, you seem to wire the potentiometers away from the basic PCB. This is always a problem, screened wire or not.
Your surprising results make me think you do not know that there are linear and logarithmic pot's around, which have to be used differently? Would explain a lot.
Learn to use your tools. Your scope has so many functions, there is one correct setting and a thousand that may show funny results. A scope should tell you in seconds what problems your power supply has or at which point of your circuit the oscillations start. Only if you know how to use it, of course!
It seems to me you jump from one point to the next without understanding what you do. Like pulling out the caps placed the integrated circuits, which need to be there and never can do any harm. So you have not understood what they do.
You ask for advice but only follow your own, unfounded, spontaneous ideas. That is playing around. Working systematically means going from the start to the end, not jumping around.
I know that in may countries "trying until it half way works" is the way to go and even called "a job" or "profession". 3 people standing around a broken thing, discussing, poking and waiting for the magic idea that will fix anything.
Consider this system not to be the best way for fault finding. If you stick to this system, you probably build in new faults while you try to fix the primary ones. Even if anyone around you may work that way.
If you go a,b,c,d and so on with a problem, you can not miss a fault. Anything else is just lottery.
If you have read until here without getting emotional, congratulations! You may start all over and find out how easy to do electronics can be (if they are that simple as yours) and you follow the rules and laws of physic. If not, I'm sorry.
Good luck!
Pot quality and their short leads are paramount. What I don't really get is why all those jumpers...they don't make sense unless the circuit was multipurposed and thus the ground routing has a chance to be desastruous.I'd use bipolar or nonpolar caps for c13, c14.
Good opamps work with 1...5 v difference between rails if the headroom is ok.I've seen circuits supplied with +5/-15v working.
Good opamps work with 1...5 v difference between rails if the headroom is ok.I've seen circuits supplied with +5/-15v working.