dirty electricity

[offgriddle]

You'd be aware of the physics of RF based heating then.
[/QUOTE I'm neither a physicist nor a physician, but it is my understanding that microwave ovens cook by exciting the food molecules at a frequency and power sufficient to cause them to vibrate together violently enough to create the heat required to cook themselves! I wonder, Is doing the same exact thing using a near field, lower level of power, (a few hundred times stronger than a microwave oven is allowed to leak), good for our delicate, electrically operated, brain and body tissues? Especially for extended periods time periods and with developing brains? Even cellphone owners manuals advice us to keep the phones away from our bodies during transmission. I have chosen to Er on the side of caution here.

 

[offgriddle]

Its broadband RFI radiating from the AC side. Slapping a big electro on the input won't make much if any difference, wrong thing to use to reduce RFI and in the wrong place. If I was worried I'd use some ferrites on active and neutral.

I would be interested in seeing that sine wave board though, so don't forget to post the link etc.

I would like to see the sine wave board too, if it's cheap enough, uses minimal power and creates a pure wave output, it might clean up my noisey inverter.

 

[offgriddle]

I would like to see the sine wave board too, if it's cheap enough, uses minimal power and creates a pure wave output, it might clean up my noisey inverter.

I have also slipped ferrites over wires to reduce RF interference heard in audio amplifiers!

 

[offgriddle]

The sort of inverter I'm taking about is a so called HF direct. LV DC in > boosted up to intermediate 400 or so volts > PWM'd to produce pretty good sine wave and pushed through an inductor to clean it up a bit.

A small bit.

What do you power with the 400 volt ac output?

 

[svetz]

I sure hope there aren't any amateur radio ops in the area!

Probably not anymore....

You guys are making me want to rent an RF meter to see what's happening here. Any suggestions?

... I use a am radio to see how horrible it is. I tried the cellphone apps and they are a joke.

Pity about the cell phone apps.
I like the idea of using the AM radio in that I have one and wouldn't have to buy yet another new tool... how's that work?

 

[svetz]

I have also slipped ferrites over wires to reduce RF interference heard in audio amplifiers!

I've seen people do that for EMP protection too. Any general rules for when it can really help and what size they should be?

 

[offgriddle]

You'd be aware of the physics of RF based heating then.

Yep

 

[gnubie]

I like the idea of using the AM radio in that I have one and wouldn't have to buy yet another new tool... how's that work?

Tune away from a station and listen for noise. In practice these days there is so much RFI coming out of everything these days that it's a miracle AM is still usable. TV sets, even old CRT types push out a lot of noise from the deflection yoke let alone the beam, personal computers blitz everything, wallwarts scream at 100-500kHz, ADSL spews out from 200kHz to 2.2MHz, VDSL goes up to 100MHz depending on the profile.

 

[gnubie]

Any general rules for when it can really help and what size they should be?

http://audiosystemsgroup.com/SAC0305Ferrites.pdf

OK, so maybe not a general rule It depends a lot on the nature of the interference. An amatuer radio OP next door pushing out 500 watts is going to push a lot of RF at your speaker leads so rings on them is where you'd attack from. Suppressing the effect of a GSM phone close to audio equipment is a whole different kettle of fish.

 

[svetz]

I'm looking for a good youtube video on it; I'll post it if I find one. In the mean time, for your amusement... Ham operators (using a racketball racket) identify SolarEdge as a noisy device....

 

[gnubie]

What do you power with the 400 volt ac output?

400V is not applied to the output, and its not the exact voltage either. 400V DC is just an approximate voltage. It might be 380, 360, depends on the inverter. Regardless the HV DC supply is not applied to the output directly. It is PWMed and then pushed through an inductor. I live in 240v (230 nominal) world. The HV rail will be lower for 110v parts of the world.

 

[svetz]

Whoa! Xantrex apparently is a pretty dirty inverter...

Update: This guys video list shows some scary things... amps on a gas line, electrified sprinkler systems?

 

[svetz]

So, most of what I see with the AM radio is if you stick the antenna on it and get a buzz it's emitting RF. But, that RF falls off if the antenna gets a few inches away. So, if those RF sources are so weak, how can they be causing dirty power?

 

[gnubie]

The signal falls off following the good old inverse square rule but if you are directly connected to the conductor you get full effect. PWM works by, typically, abruptly turning the current on and off with the duty cycle and/or frequency changing. That abrupt change in flow creates a squarish waveform, and that means a whole slew of harmonics. Cheap direct PWM inverters only have just enough output filtering to allow the recreation of the sine wave. A bucket of those harmonics still get through, attenuated sure, but still there. That's the dirty part of the waveform.

Do they cause problems with the devices being powered? Usually no. It's only the RF world that suffers.

 

[offgriddle]

400V is not applied to the output, and its not the exact voltage either. 400V DC is just an approximate voltage. It might be 380, 360, depends on the inverter. Regardless the HV DC supply is not applied to the output directly. It is PWMed and then pushed through an inductor. I live in 240v (230 nominal) world. The HV rail will be lower for 110v parts of the world.

Gnubie your so tekky your losing me here! I like it by the way, but im still not sure how your using 380/360 yada voltage ....

 

[offgriddle]

I've seen people do that for EMP protection too. Any general rules for when it can really help and what size they should be?

Hi Svetz! I have slipped ferrite beads over copper telephone wires and power supply wires to suppress Electro Magnetic Interference. Understanding what ferrite is and how it works is a science all of it's own and its not even fully understood! I cannot answer your question, I wish i could! You're going to have to "duck duck go" it! Namaste! PS: "ferrite is a ceramic material made by mixing and firing large proportions of iron oxide blended with small proportions of one or more additional metallic elements, such as barium, manganese, nickel, and zinc".

 

[offgriddle]

Tune away from a station and listen for noise. In practice these days there is so much RFI coming out of everything these days that it's a miracle AM is still usable. TV sets, even old CRT types push out a lot of noise from the deflection yoke let alone the beam, personal computers blitz everything, wallwarts scream at 100-500kHz, ADSL spews out from 200kHz to 2.2MHz, VDSL goes up to 100MHz depending on the profile.

Also, Gnubie and Svetz, just a plain old audio amplifier can detect when a cellphone is transmitting, (probably via the copper speaker windings acting as an antenna to pick up the cellphone RF signal which back-feeds through the audio amplifier, thus, creating a very clear and distinct digital signal noise). My Goal Zero Rockout 2 speaker does this with perfect accuracy. It is amazing how often your cellphone transmits on it's own even when your not using it. Rockout 2 >> https://www.amazon.com/Goal-Zero-Wi...=2025&creative=165953&creativeASIN=B0136ZTQ8W

 

[offgriddle]

The signal falls off following the good old inverse square rule but if you are directly connected to the conductor you get full effect. PWM works by, typically, abruptly turning the current on and off with the duty cycle and/or frequency changing. That abrupt change in flow creates a squarish waveform, and that means a whole slew of harmonics. Cheap direct PWM inverters only have just enough output filtering to allow the recreation of the sine wave. A bucket of those harmonics still get through, attenuated sure, but still there. That's the dirty part of the waveform.

Do they cause problems with the devices being powered? Usually no. It's only the RF world that suffers.

The inverse square law, be still my heart! The inverse square law says: "it takes four times the RF transmitter power to make twice the difference at the receiver". U R Fun Gnu.

 

[b.james]

Microwave ovens are allowed to leak 5 milliwatts as measured at about 2" from the oven, Cellphones transmit at 600 milliwatts which is why I'm not so keen on pressing one against my temple!

Well it jumps up in emergency so stand back!

 

[svetz]

Halogen bulbs in the range hood burned out and replaced them with higher wattage LEDs. Dang things are flickering and in the back of my mind is... those little #^@%*& are probably noisy! My fault really... I went with the cheapest (amazon basics); now I'm thinking I'll have to try and find some quality LEDs in a sea of noisy LEDs. I don't suppose anyone has a litmus test for this?

Update: I'm such a putz... should have read the reviews:

The bulbs flicker at about 60hz. I don't even have epilepsy and I felt highly disoriented. I can't imagine cooking under these things.

Update 2: To get "flicker-free" you need to look for that as a feature; go figure.