AC Filtration

[speakerman1]

I bought some lead sheets and Kevlar cloth. Need to get some release paper , resin and shears. Carbon would be a conductor would Kevlar. I know I'm using a resin it would insulate pretty good. I'm going to set up a vacuum system to do veneer. Could use a simple venturi to do it; but they are noisy. LOL

 

[Pure_Brew]

I havent got the transformer or done any testing, but I have taken note that this will first occur right around 5-5:30 am. My voltage runs at 123.8 according to the Belkin during the wee hours. It'll drop a volt or go up a volt during the noise time. The voltage during the day fluctuates downward, which I'm sure is natural.

I was in the kitchen and noticed something behind my stove clock buzzing, so I figured it was happening in my audio room too, and it was. So this noise effects other things too.

The only thing I can think of that would throw that kind of noise (if it is occurring inside the building) is something furnace or maybe even heater related. If it keeps occurring at any consistent time, it could kick in when the neighbor takes a shower, and he does get up around that time.

I didn't notice yesterday, and I've only kept track a few days so we'll see.

 

[speakerman1]

Yes at night early morning voltage will be up. Less users. How long does the noise last?

 

[speakerman1]

See if we could design a passive filter it would take care of the noise

 

[speakerman1]

Well I got the lead but no test subject. LOL

 

[Pure_Brew]

What are you doing with that stuff?

 

[speakerman1]

Isolate EMF. I have one transformer that isn't a toroidal. Going to see if I can eliminate it. I have Kevlar cloth coming also. See if that may do it. Don't know how to measure it.

 

[Pure_Brew]

The smaller points jutting up and down seem to have something to do with the scope or probe. Either way it looks like poo. This is coming off 9v AC from a wall-wart supply i picked up today there was noise so I figured it'd be a good time to look.

However, the noise does seem to be effecting the scope too (it is ancient after all). So with just the prob plugged in, I get a noise and this is what it looks like.

 

[Pure_Brew]

Ok now the noise is gone, but these waveforms look pretty much the same but those vertical spikes are now gone.

EDIT: The second picture above (triangle) is just noise from what appears to be the unshielded probe. I tried a shielded RCA cable after which cleaned that up, but the AC trace is still pretty much the same.

 

[Gepetto]

Joe
I was guessing that you had lousy crest factor on your AC waveshape and this photo shows it. The crest factor is the waveform voltage peak divided by the RMS voltage. Ideal AC waveforms has a crest factor of 1.41. A square wave for reference has a crest factor of 1.

The noise spikes that you see on the falling edge of the waveform look like someone is running an SCR or Thyristor controlled device on your building AC line (light dimmers, heaters, etc.)

 

[Gepetto]

Forgot to ask Joe, is this waveform picture taken at the time you hear the noise in your equipment? Or does it get worse than this?

 

[Pure_Brew]

The noise I'm having the issue with, seems to be when those spikes appear. I just tried this for the first time last night, might be good to try a few more times.

To clarify, the noise occurred in the first pic, no noise in the last.

Other transformer noise issues I'm having might relate to the waveform as it is, but it is minor compared to the noise when those spikes appear. But yes, for now ill say the AC looks about the same all the time otherwise.

However I can not fully interprate what I see there, just relative comparisons.

 

[speakerman1]

Do you have an extra IEC cord? If so I'll let you try something. It may help.

 

[Pure_Brew]

Wow could a fluorescent light in my neighbors kitchen be causing this? Again, it's the spikes that appear during this noise. Makes my panel buzz too!


I know he's up at around 5-5:30 AM, down around 9-10pm and this is around the time of the noise. They usually do not leave lights on.

So, I'll ask him when I see him to try turning it on and off. But what could I do to get rid of it on my end.

 

[Pure_Brew]

99% Sure it's a florescent light in my neighbors house now. I just met him outside and asked him if he could help solve a mystery. He shut if off, I ran in, noise eliminated.

The scope confirms that these spikes( )reappear during the noise event. Waveform shape is however always about the same.


It's causing things like my Belkin, Stove, electrical panel & amp (when on) to emit buzzing.

So let's say there is nothing I can do on his end. What can I do on mine end, at least for my audio system? Isolation Transformer? No clue.

 

[orange]

Offer to fix his ballast or replace the fluorescent tube. He might be quite happy to cooperate in the future.

 

[orange]

Jerry the reply button is stuck on the post before and I'm being told I'll lose the comment if I move away.

 

[Pure_Brew]

Offer to fix his ballast or replace the fluorescent tube. He might be quite happy to cooperate in the future.

Since we both rent I think I'd have to ask the landlord about it. But that is a good point. The landlord is usually a decent guy. Been nice to me and my family for 15 years. It's funny that this neighbor has been so consistent about getting up, going to sleep and always shutting things down. I think the renters before used to just leave that light on all the time, so I had the noise pretty much all the time.

But it's curious that we are on separate services and I get this noise? Maybe separate services is the wrong way to put it.

 

[Gepetto]

Joe
The best way to eliminate noise is to stop it at the source rather than trying to filter it out, so agree you should take the landlord approach first. In general your line quality is awful with that poor crest factor. That does no good for any of the equipment running off of it. That you should try and address too, that may be with the power company.

 

[Gepetto]

Joe
This is a sampling of my local AC, there is some attentuation of the peak due to stuff with lousy power factor running but no where near what you are seeing.