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Class D Switching Power Amplifiers and Power D/A conversion

Careful attention to Digital power amplifier of electromagnetic waves.
Careful attention to Digital power amplifier of electromagnetic waves.
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Old 26th September 2015, 02:19 PM   #1
ljm_ljm is offline ljm_ljm  China
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Default Careful attention to Digital power amplifier of electromagnetic waves.

It will produce very high electromagnetic radiation outside the 30 cm.

Shielding inductive slightly better. But still exist.

A bigger ring inductance radiation.

Almost no attention to the high frequency interference caused by radiation.

Advice from your digital amplifier 3 m above the distance.
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Old 26th September 2015, 02:37 PM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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What is the context? Seems to be an answer to a previous thread??
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Old 26th September 2015, 02:48 PM   #3
kouiky is offline kouiky  United States
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I think it's a general post. It's the language barrier that causes it to appear as a reply rather than a thread starter.

In general, I agree that switch mode circuits can sometimes introduce interference, I've experienced it. The thing is, there has to be some mention of the actual circuitry if we're going to state factors and distances as conditions leading to it. Without that there are no real qualifiers.
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Old 26th September 2015, 02:54 PM   #4
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by kouiky View Post
I think it's a general post. It's the language barrier that causes it to appear as a reply rather than a thread starter.

In general, I agree that switch mode circuits can sometimes introduce interference, I've experienced it. The thing is, there has to be some mention of the actual circuitry if we're going to state factors and distances as conditions leading to it. Without that there are no real qualifiers.

That's right. I measured by square wave PWM voltage in the air.

The closer distance circuit board, the higher the voltage, it is very big.

Shielding inductive voltage slightly lower, toroid is larger.

Note that is measured in the air, no access to the electronic components.

In addition, I also has carried on the electromagnetic tester for measuring, it very large electromagnetic signal.


Under normal circumstances no one noticed it.

I think digital power amplifier to produce these in the air waves, on the human body may have an effect.

May be hurt.
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Old 26th September 2015, 02:56 PM   #5
ljm_ljm is offline ljm_ljm  China
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I recommend that the location of the digital power amplifier placed far away.

3 m may be better.
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Old 26th September 2015, 03:35 PM   #6
kouiky is offline kouiky  United States
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SMPS, I can relate to problematic interference and acoustic noise there. To prevent the electrical noise from being passed on to the circuit being powered, follow up the SMPS with a linear regulator having a high PSRR at frequencies corresponding to those on the line. Anyway, everyone knows that. I wonder if a thin metal shield encapsulating the SMPS' inductor would be enough?
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Old 26th September 2015, 08:33 PM   #7
ChocoHolic is offline ChocoHolic  Germany
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It sounds like ljm_ljm is concerned about the radiated electromagnetic field.
Many people are suspecting electrical, magnetical and electromagnetical fields to impact the health even when the concerned fields of low magnitude.
Scientific examinations in these fields are difficult and of course not just some big companies, but basically all highly developed modern societies have a massive interest in declaring such fields as harmless.
Imagine the hazzle, when we suddenly have to worry about the 50Hz or 60Hz fields due to the normal installations in our houses and flats.
Imagine the hazzle, when we suddenly have to worry about multi GHz waves due to mobile phones,DECT phones, WLAN, Bluetooth, LTE etc...
Imagine the hazzle with induction cooking plates.
Everybody knows the discussion about microwave stoves.
Imagine the hazzle with your computer (fully packed with switch mode power electronics) and TV screens...
Already from scientific view it is a difficult topic to investigate which sort of field may have which kind of influence on the human body, but in combination with business considerations and our human emotions and most people having no clue about physics nor biology there has already evolved an extremely unrational war between people of opposite believes.

Fact is that we usually do not get killed immediately, when using a microwave stove.
Fact is also that we are generating lots of different fields with magnitudes which are significantly higher (often factors of multiple ten thousands) than the natural fields would be in any of the concerned frequency ranges.
Means we have implemented a massive change of our living environment.

ljim_ljim:
How does your field probe look like?
Is it for electrical fields or magnetic fields?
How many V/m or nT do you measure in a certain distance?
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Old 2nd October 2015, 11:22 AM   #8
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by ChocoHolic View Post
It sounds like ljm_ljm is concerned about the radiated electromagnetic field.
Many people are suspecting electrical, magnetical and electromagnetical fields to impact the health even when the concerned fields of low magnitude.
Scientific examinations in these fields are difficult and of course not just some big companies, but basically all highly developed modern societies have a massive interest in declaring such fields as harmless.
Imagine the hazzle, when we suddenly have to worry about the 50Hz or 60Hz fields due to the normal installations in our houses and flats.
Imagine the hazzle, when we suddenly have to worry about multi GHz waves due to mobile phones,DECT phones, WLAN, Bluetooth, LTE etc...
Imagine the hazzle with induction cooking plates.
Everybody knows the discussion about microwave stoves.
Imagine the hazzle with your computer (fully packed with switch mode power electronics) and TV screens...
Already from scientific view it is a difficult topic to investigate which sort of field may have which kind of influence on the human body, but in combination with business considerations and our human emotions and most people having no clue about physics nor biology there has already evolved an extremely unrational war between people of opposite believes.

Fact is that we usually do not get killed immediately, when using a microwave stove.
Fact is also that we are generating lots of different fields with magnitudes which are significantly higher (often factors of multiple ten thousands) than the natural fields would be in any of the concerned frequency ranges.
Means we have implemented a massive change of our living environment.

ljim_ljim:
How does your field probe look like?
Is it for electrical fields or magnetic fields?
How many V/m or nT do you measure in a certain distance?
Digital power amplifier. Radiation bigger than we thought.

10 cm. You can use the oscilloscope, the distance can be very clear, as measured by square wave,

About dozens of V voltage.

Near the inductor is the most obvious. Be careful not to touch it.

I use the electromagnetic wave radiation tester, digital power amplifier is far more than any electrical radiation.

Of course, I don't have it installed in a metal case. Maybe it will be reduced.
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Old 2nd October 2015, 11:27 AM   #9
billshurv is offline billshurv  United Kingdom
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Careful attention to Digital power amplifier of electromagnetic waves.
Quote:
Originally Posted by ljm_ljm View Post

Of course, I don't have it installed in a metal case. Maybe it will be reduced.
That is likely to be your problem. It is a bit foolish to do that.
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Old 2nd October 2015, 02:14 PM   #10
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by billshurv View Post
That is likely to be your problem. It is a bit foolish to do that.
Yes. Maybe can try to use the lead, the production of Shell.
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