True for new buildings, but I live in house from 1956 - I do not have a neutral. It was me who did the whole electricity for the house so I have some idea😉
Ah OK, so you belong to the "very old systems" 🙂
I´m stll using my balanced AC system with a 2 x 115V transformer to avoid DC and add some filtering. Works fine.
William
I´m stll using my balanced AC system with a 2 x 115V transformer to avoid DC and add some filtering. Works fine.
William
Anyway, I am a bit puzzled. I am getting the same result as this guy here:
Mains DC and Transformers
when I use only diodes - trafo is still humming. It seems though that this is being used in commercial equipment! I will try with caps next, as described in above link.
Mains DC and Transformers
when I use only diodes - trafo is still humming. It seems though that this is being used in commercial equipment! I will try with caps next, as described in above link.
No, this keyword I don't read. OTOH - if there are no "Neutral" mains connector at your home, means this for me at the same time, that there is no "safety earth" in use. Otherwise there must be a "Neutral" mains connector present.
Do you create your balanced AC system with help of an isolating transformer?
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There is safety earth, but no neutral. And you are right, I don't see how this is related to this topic.
With sadness in my eyes, I can report that neither method works for me. The next thing to try is post 14 from this thread:
http://www.diyaudio.com/forums/solid-state/39895-transformer-making-noise-how-cure-2.html
before I start assuming it's not a problem with DC.
http://www.diyaudio.com/forums/solid-state/39895-transformer-making-noise-how-cure-2.html
before I start assuming it's not a problem with DC.
Ask your self the question(s)
How do you know you have DC Offset
How do you know the hum is caused by natural transformer noise with perfect mains
How do you know you have DC Offset
How do you know the hum is caused by natural transformer noise with perfect mains
I will, thanks. How about simply two elcos of 400V 560uF in parallel? If there is higher DC then 2X forward voltage, that should take care of it for sure? I got two from a switcher PS.
Hi,
the elcos only need to be 16V or so. They will never see more than 1,4 volt if you use two diodes. And even if you don´t the voltage is very low if the capacitance is high enough.
Read post #16 from the thread mentioned above, here everything is mentioned correctly.
William
the elcos only need to be 16V or so. They will never see more than 1,4 volt if you use two diodes. And even if you don´t the voltage is very low if the capacitance is high enough.
Read post #16 from the thread mentioned above, here everything is mentioned correctly.
William
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I meant without the diodes - just two caps in parallel. Then I remembered that they are rated 420VDC for forward voltage only😉
Hi,
even without diodes the voltage over the caps only depends on the current that flows and the inner resistance (ESR?) of the caps. Normally it should be very low (lower than 1 Volt).
William
even without diodes the voltage over the caps only depends on the current that flows and the inner resistance (ESR?) of the caps. Normally it should be very low (lower than 1 Volt).
William
OFFTOPIC: can anyone drive me to where my problem is discussed?
A buzz in the output, that comes and goes, clearly due to an external source, from outside of the place (maybe some neighbors' appliance).
My set is an amp with built-in mixer, and this bothers me a lot while using the microphones.
I have noticed that earth settings are very important in this case, and I need to review my setup.
Thanks a lot.
A buzz in the output, that comes and goes, clearly due to an external source, from outside of the place (maybe some neighbors' appliance).
My set is an amp with built-in mixer, and this bothers me a lot while using the microphones.
I have noticed that earth settings are very important in this case, and I need to review my setup.
Thanks a lot.
A little safety warning
It seems a little safety warning is in order.
Potential very dangerous... don't even think about it !
Suitably rated diodes are the circuits safegaurd. It MUST be safe under all conceivable conditions, fault or otherwise. What about startup. What about one cap changing value or going high ESR ?
It must have been linked to several times but this covers it all,
Mains DC and Transformers
It seems a little safety warning is in order.
Potential very dangerous... don't even think about it !
Suitably rated diodes are the circuits safegaurd. It MUST be safe under all conceivable conditions, fault or otherwise. What about startup. What about one cap changing value or going high ESR ?
It must have been linked to several times but this covers it all,
Mains DC and Transformers
It does not work for me, with or without caps (in series). With snubber on both secondaries, it gets even worse!
I will try to put two dc blocker sets now, that should block up to 3V I guess.
Why are we all assuming that everyone has DC < 1.4V on the line? It could be much worse in my case.
Well, I removed all filters and snubbers, and hum has gone down significantly😉
If add/remove them few more times, it might be completely gone😉
It seems I do not have any DC at mains after all. The faint "purrr" I hear is probably due to PCB being too close to toroid. It might make sense to separate them with steel plate, but that's a project for New Year. Speaking of which, marry Xmas and Happy New Year everyone
If add/remove them few more times, it might be completely gone😉
It seems I do not have any DC at mains after all. The faint "purrr" I hear is probably due to PCB being too close to toroid. It might make sense to separate them with steel plate, but that's a project for New Year. Speaking of which, marry Xmas and Happy New Year everyone
OFFTOPIC: can anyone drive me to where my problem is discussed?
A buzz in the output, that comes and goes, clearly due to an external source, from outside of the place (maybe some neighbors' appliance).
My set is an amp with built-in mixer, and this bothers me a lot while using the microphones.
I have noticed that earth settings are very important in this case, and I need to review my setup.
Thanks a lot.
I had a similar issue with a power amp and the cause was incorrect grounding. It took a lot of thinking over what was happening but eventually a 100% fix was found. As the mains "quality" varied a very noticeable buzz appeared on the audio output. A scope check showed the presence of tiny pulses of data on the mains when this occured... some form of mains signalling somewhere and always at the same times of day. Its a residential area and I've no idea what they were unless possibly generated by the electric company (they were looking at developing broadband via mains wiring but it never came to anything).
You would have to read all this starting around post #8
http://www.diyaudio.com/forums/solid-state/101321-3-stage-lin-topology-nfb-tappings.html#post1617990