24-05-2020, 08:57 AM
(This post was last modified: 24-05-2020, 09:02 AM by ppppenguin.)
In the days when there were lots of TVs with halfwave rectifiers. DC on the mains must have been quite severe. The power network people must have cared but couldn't do much about it. Customers wouldn't have noticed anything back then. The power network people don't like waveform distortion. 3rd harmonic current is nasty because it gives a lot of excess neutral current in 3 phase systems.
How do DC removers work? I don't think you could readily put a great big capacitor in series with the mains. Can you measure DC on the mains with just a DC voltmeter? Decent DMMs should withstand the 230VAC but will the result make sense?
Old joke that circulated at one workplace. Somebody complained of "hum on the mains". The solution: "decouple it with a large electrolytic". AFAIK, nobody tried this, or if they did, it was well out of hours, they never admitted it and they cleared up thoroughly.
PS: Just read the article and found that a DC blocker is basically big back-to-back electrolytics protected by diodes across them.
How do DC removers work? I don't think you could readily put a great big capacitor in series with the mains. Can you measure DC on the mains with just a DC voltmeter? Decent DMMs should withstand the 230VAC but will the result make sense?
Old joke that circulated at one workplace. Somebody complained of "hum on the mains". The solution: "decouple it with a large electrolytic". AFAIK, nobody tried this, or if they did, it was well out of hours, they never admitted it and they cleared up thoroughly.
PS: Just read the article and found that a DC blocker is basically big back-to-back electrolytics protected by diodes across them.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
