Well, I had no ground, I connected a wire to a chassis. When I connected that wire to a waterpipe, the noisy hum disappeared.
When I connected that wire to a steel pot full of fresh water, the noise also disappeared, but it came back in a short while.
I was using a high gain amp with a low V source and highly efficient low wattage fullranges, so the noise from the dirty AC power I had access to (the mains) that made it through the trafo was pretty loud.
All that gain from the amp plus all the noise from the mains made a nasty buzzy hum, Nowadays I do not use such a high gain power amp, and the mains is a little bit cleaner than it was when I tried that, but it is certainly not UK or USA quality power.
Well that is often the case, But if you talk to some ham radio enthusiasts, they make their ground a ground, like driving a metal stake into the ground a few feet down.
Or if you use a powerful enough shortwave, that picks up noise from the mains too, as the whole radio, including the parts that amplify those tiny signals from around the world is all connected together, so if noise makes it into the amps inside a good shortwave, the effects can be enough to ruin a good broadcast.
I know one wire is neutral, but would not trust the electricians to get tht correct here, and that wire is part of the loop.
Ground should be ground, but people who get paid by the job take shortcuts, and radios are not so popular anymore, and switching power supplies usually provide enough isolation for the digital equipment they power, these days.
I might as well be specific abut the type of EMI filter that saved the particular veeerrrrrrryy loooooong day
it was one of these, not that brand, but same exact look,
https://3.imimg.com/data3/WN/LO/MY-5117174/emi-filter-250x250.jpg
I do wonder if bigger is better with those, but I have a hunch that overshooting on the Amps too highly would only allow more noise through.
Maybe a bigger one without a higher current capacity would be better, but that one was sufficient for me this time
it was one of these, not that brand, but same exact look,
https://3.imimg.com/data3/WN/LO/MY-5117174/emi-filter-250x250.jpg
I do wonder if bigger is better with those, but I have a hunch that overshooting on the Amps too highly would only allow more noise through.
Maybe a bigger one without a higher current capacity would be better, but that one was sufficient for me this time
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That indicates to me a very poor wiring scheme somewhere along the line. It's impossible to know where exactly the problem is without you drawing a detailed diagram of all the equipment and interconnects.
I was at a beach house in SC when I was a kid. There was the strangest warning there. I think it was about the stove and the fridge. It said "DO NOT TOUCH THE STOVE AND THE REFRIGERATOR AT THE SAME TIME, OR YOU MAT BE ELECTROCUTED"
I was also told a story about a guy who was working on an elevated platform, near some stoplights and power lines. He was out in the country, no one was there to see him at the time, working up high right next to some HV lines, and had to take a leak. He thought it was all good because no one was looking, and did not test the voltage difference between the fields up there around those lines and the ground. And he did not make it.
I was also told a story about a guy who was working on an elevated platform, near some stoplights and power lines. He was out in the country, no one was there to see him at the time, working up high right next to some HV lines, and had to take a leak. He thought it was all good because no one was looking, and did not test the voltage difference between the fields up there around those lines and the ground. And he did not make it.
DId you know that a faraday cage must be grounded? Ever had a look at the AC mains power in downtown Bangkok Thailand with a scope??. It looks like two sine waves of different wavelengths multiplied together, and it is not all pretty like the power in your first world.
It was a tried and tested PCB, same circuit used in thousands of P.A. systems here and in your country, but the mains was dirty and there were also flourescent lights only in that building. Hmmm, Humm???
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+1, not true.
People forever confuse 'Earth/Ground' as some magical 'noise sink', when the truth is : all voltages - therefore all currents - are differential. Deal with that properly, and you'll there's no need for a third terminal.
This was pointed-out by DF96 in post 5; and as usual here, totally overlooked.
People forever confuse 'Earth/Ground' as some magical 'noise sink', when the truth is : all voltages - therefore all currents - are differential. Deal with that properly, and you'll there's no need for a third terminal.
This was pointed-out by DF96 in post 5; and as usual here, totally overlooked.
I might want to quibble the "therefore".martin clark said:
Voltages are differential because the electric field is a 'conservative' field (under quasi-static conditions); it can be fully described by a potential function.
Currents flow in loops because of electric charge conservation.
As far as I know these two properties of the electromagnetic field are unrelated, although always true. Sadly, they also seem to be relatively unknown to many audio people who then go on wild goose chases for 'clean grounds' etc. when all they actually need to do is apply Kirchoff's two laws.
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