Linear power supplies....Bio safe voltage.

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Re: Linear power supplies....Bio safe voltage.

Karl
It turns out that my router/switch runs OK on 10V, so I'm using my new power supply to post this message*. Here's a pic:



It got a bit noisy when I adjusted it up to 11V, so that's why I backed down to 10V. It's now slightly quieter on my AM radio than the Jameco linear-regulated power supply it replaces.

(*It wasn't running when I took the picture. The paper towel was just a convenient backdrop.)
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
This was taking down 120AC to 10vDC?   Nice one!   How do you shield out all the muck from your router?  I have a big Ali box.  Then a bunch of ferrite chokes.  I find the worst source of wifi comes in down the phone line.  ADSL filters or ferrite will sort that though.  
      Have you made Faraday enclosure boxes for  electrickery units?  What works best?  Copper Ali Foil paint or tape?    
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Re: Linear power supplies....Bio safe voltage.

Karl
Plop Plop wrote
This was taking down 120AC to 10vDC?
Yep.

 Nice one!
Thanks :)

How do you shield out all the muck from your router?  I have a big Ali box.
I'm using aluminum screen held together at the edges with clothes pins. Tha makes it very easy to get access to the ports if I need to.

Then a bunch of ferrite chokes.
Same here. I used clip-on ones at first, but now I have the cat-5 cables wound around toroids.

I find the worst source of wifi comes in down the phone line.  ADSL filters or ferrite will sort that though.
We switched to fiber phone and internet here, but before that I did the same thing - lots of ADSL filters in series.

Have you made Faraday enclosure boxes for  electrickery units?  What works best?  Copper Ali Foil paint or tape?
I've used aluminum foil, copper pots and graphite paint. The paint didn't stop my AM radio from picking up noise, but seemed to make me feel better, which is kind of odd.
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Re: Linear power supplies....Bio safe voltage.

Karl
In reply to this post by Karl
I forgot to mention one things about the transformer: I put a steel can over it as a cheap first layer of magnetic shielding, and then a layer of purified iron foil as a second layer.
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
 have the cat-5 cables wound around toroids.   Not sure what this is???  Do they work well?  

I have been making shielded cable with foil tape.  They work but crack.  Paint does not seem to work at all???

Have you tried anti solar radiation paints filled with Aluminium?   I am going to make some my self.  I help at a scrap yard and someone weighs in Ali dust and I am hoping to get some.  

I want to try Ali graphite and carbon black.   I may try a power mix to see if these are as good as they should be.  

You say "I put a steel can over it as a cheap first layer of magnetic shielding, and then a layer of purified iron foil as a second layer."

How does that mag shield?   Whats iron foil?    Is ali not better?   I want copper foil but cant find any.( for a new hat).  
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Re: Linear power supplies....Bio safe voltage.

Karl
In the future I think I'll use this transformer instead:

https://www.ebay.com/itm/25VA-9V-9V-18VCT-Power-Transformer-Antek-AN-0209-/372052498295?hash=item56a00e9777

Each regulator input on the board needs to be 1.5-3V higher than the output voltage, and there are two of them (one on positive and one on negative). So 9/18V (parallel/series) should leave enough headroom to generate either 5V or 12V.

Plop Plop wrote
have the cat-5 cables wound around toroids.   Not sure what this is???
It's the same winding technique that I use for my keyboard and mouse:



It's just an easy way of making a common mode choke: https://product.tdk.com/en/products/emc/guidebook/eemc_product_05.pdf

I have been making shielded cable with foil tape.  They work but crack.  Paint does not seem to work at all???
I have some of this, but it's expensive: https://www.jameco.com/z/1321-100-Wire-Tubular-Tinned-Copper-Braid-3-8-Inch-384x36-Stranded-100-Feet_2124162.html

Have you tried anti solar radiation paints filled with Aluminium?
No, but I've tried Rust-Oleum zinc paint. It's not conductive (as per my multimeter), and it didn't block AM or FM radio.

You say "I put a steel can over it as a cheap first layer of magnetic shielding, and then a layer of purified iron foil as a second layer."

How does that mag shield?   Whats iron foil?
https://www.ebay.com/itm/99-995-Pure-Iron-Foil-Fe-Thin-Sheet-0-3mm-x-100mm-x-1000mm-EF-4-/171873101486?hash=item28046f66ae

http://www.jfe-steel.co.jp/en/research/report/006/pdf/006-06.pdf

Is ali not better?
Aluminum is a lot better for high frequencies, but 60Hz will go right through it. You need to do this for mains-frequency transformers:

https://www.youtube.com/watch?v=EeAcGell_cg

https://www.kjmagnetics.com/blog.asp?p=shielding-materials

http://ieee.rackoneup.net/rrvs/09/Engineering%20Aspects%20of%20Electromagnetic%20Shielding.pdf
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
Is "cat-5 cables " USB multi core?  

"Aluminum is a lot better for high frequencies, but 60Hz will go right through it. You need to do this for mains-frequency transformers:"     Like I said on my 220vAC cables ali foil tape stops my electric field meter reading 1400 down to 0.   Do you know what sort of field it is reading? I have tried asking every one and no one knows???


I had a wall of galvanised steel sheets but found that would not cut down my neighbors EMR noticeably at all. I had to move out.   I will try to watch those videos.  I am on a copper wire miles from an exchange in France so its very slow.

Do you know much about earthing stuff?  I am ready to put in a new earth but keep wondering if I should do it differently. Lots of doubts??

Thanking you!  Much appreciated.
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
In reply to this post by Karl
I dont worry about magnetic fields I just stay clear of them as they don't travel far. I dont have a hard drive or use DC motors.  My linear mag amp makes it but I stay away.

VERY different in cars though.  Modern vehicles are stinking with magnetic fields that are killers.  People should be warned and protected. Its like they want to kill all EHS. Seriously. The worst thing is that this effect every ones biology equally and is enough to clog ones blood causing accidents and killing etc.

The EU measure the average for a vehicle and not where the driver sits.  I wonder who got the back hander for that??  It stinks!   Have you seen the readings for trains????
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Re: Linear power supplies....Bio safe voltage.

Karl
In reply to this post by Plop Plop
Plop Plop wrote
Is "cat-5 cables " USB multi core?
It's old ethernet cable.

I had a wall of galvanised steel sheets but found that would not cut down my neighbors EMR noticeably at all. I had to move out.
That's kind of surprising, since zinc is a pretty good conductor and steel sheet is almost always a lot thicker than aluminum foil.

Do you know much about earthing stuff?  I am ready to put in a new earth but keep wondering if I should do it differently. Lots of doubts??
Unfortunately not yet. My ground is lousy because all of the stuff I care about is on a third floor and the house ground is noisy.
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
Neighbors can be a huge problem.
     Is there any thing you can put in an wire earth that will block radio waves coming in? Mine seems to be a very good radio antenna so Im not sure if its doing more harm than good at times. I only hold it at low signal times.
   I have a EMR conductive floor paint covering my attic but I am not sure if I should earth it. Any thoughts?  The science geeky ham stuff  about this confuses me. Will it enable long wavelengths to short to earth better? I am sure it has already done some good as I have not had a bad evening since painting it. Before some days were terrible with my radio wave tinnitus.
  Some one should write EMR protection for dummies.  

I like living on 12vDC but its not easy. It is good to meet a fellow user. DC is a much better healthier way to be but only if you get it right. People do not seem to realise the dangers from dirty transformers. They probably do more harm to health than MWs. We really need standards for dirty electricity in France and the UK.  
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Re: Linear power supplies....Bio safe voltage.

Karl
I use a coaxial cable for my ground wire and run it down to the basement through an old steel clothes chute.

I'm still reading about this in a book I bought recently, but it may be that double-shielded coaxial cable is required in some cases.

The book says that grounding isn't required for shielding enclosures that have no wires penetrating the shielding. I'm not sure if that applies to electric fields, though.
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Re: Linear power supplies....Bio safe voltage.

Karl
This post was updated on .
In reply to this post by Karl
I just ordered three of the Antek transformers, but they won't come for a few more days. So right now I'm setting up a 115V->15V transformer that I had ordered earlier and just received in the mail.

I also have a couple of regulator boards that should come by this evening*, so by tomorrow I hope to have the fiber modem and IP telephone box converted.

(*I bought a couple of "Knacro"-branded LM317/LM337 boards on Amazon because they offered one-day shipping.)
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
In reply to this post by Karl
"double-shielded coaxial"  seems to offer advantages.  The surface effect is important for radio frequencies but for earthing I am not sure. No, I think you are right. The more I read the more confused I get.  It seems like every one knows but no one does.  Will long wave length short better with a ground earth?   Logic says yes but I dont know. For MWs its not necessary.  Waves under the size of your conductive surface should short at least in part. Does shorting cut waves? It seems likely to me.  Why is all this so hard to find on the Internet? It seems the idea of shorting should not be mentioned any more. May be its not politically correct in the context of MW winging any more.
      I would much rather short the stuff before it shorts in me.
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Re: Linear power supplies....Bio safe voltage.

Karl
In reply to this post by Karl
I converted the fiber modem this morning.  It all looks good so far.

The new board is slightly smaller in footprint than the other one, and I think slightly taller (from the PCB to the tops of the capacitors). The adjustment screws on the potentiometers are easier to access, but it doesn't have the handy through-hole contacts for measuring the setting.

There's also a mildly annoying blue LED on the board. It's probably a safety feature to prevent people from touching wires while it's turned on, but I had to cover it up with tape while I was taking under-load measurements of the output voltage and balance.
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Re: Linear power supplies....Bio safe voltage.

Plop Plop
Banned User
Whats a fiber modem?   I am a bit of a retard at modems. What are the advantages?
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Re: Linear power supplies....Bio safe voltage.

Karl
Plop Plop wrote
Whats a fiber modem?   I am a bit of a retard at modems. What are the advantages?
It's optical internet. Here's my ISP's page: http://fiber.usinternet.com/

The main advantage it that there's one less thing to filter.

It's expensive in many places, but here it's fairly affordable.

---

Some more details about the new board: It uses two Bouter 3296 trimpots for adjustment: https://www.bourns.com/pdfs/3296.pdf

They weren't set to a sensible value when the board arrived, and I needed a bright light to read the part number and identify them. You have to flip the board over and measure the resistance across the pins as you make adjustments, and then you have to fine-tune it under load.
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Re: Linear power supplies....Bio safe voltage.

Marc Martin
Administrator
For the optical / fiber internet, I've heard complaints from sensitive people that the box which converts the fiber signal into regular ethernet is intolerable.  So I'm hesistant to try that, especially since my current cable internet setup is tolerable.

Marc

 
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Re: Linear power supplies....Bio safe voltage.

Karl
Marc, I had the same concern when it was installed, but I had no choice in the matter. The owners made the call, and I just had to roll with it. It's better than the DSL we had earlier, but I can't compare it to cable.
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Re: Linear power supplies....Bio safe voltage.

Karl
In reply to this post by Karl
I got more noise than I expected when I checked the new power supply with my AM radio, so I took it to the room where I tested the other one and used the same set-up. In those conditions it's very quiet.

It sounded worse than my Jameco AC adapter when I hooked it up to the modem, but my radio sometimes has trouble picking up higher frequencies when it's near a transformer. I'll have to test again with the transformers farther away.
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Re: Linear power supplies....Bio safe voltage.

Marc Martin
Administrator
In reply to this post by Karl
Yes, for me, DSL was the worst, and it got progressively worse as the speeds increased.  For that, the telephone wiring throughout the house was causing me issues.  Cable was a big improvement, especially when I installed a ground-loop eliminator (as my cable and the electricity have different ground sources).

Marc


 
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