Elimating EMF or elecrical magnetic interference

**Barnacle Bill** · 01-14-2012, 04:44 PM

First of all let me say that I cannot ever remember having a problem with interference when I provided power to equipment using this method. I learned it years ago when I got into the telephone industry and why I haven't mentioned it before is beyond me. UTP or unshielded twisted pair wires was invented by Alexander Graham Bell. The wires are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources. (I had to look this up) Twisted pairs are used not only in telephone lines but also in the computer world.

You may wonder why UTP isn't used more extensively than it is and the reason is simple. COST. It takes twice as much or more twisted wire for a run than untwisted wire.

I make my own and it is very easy to do. Say you have to run power to your new depth finder and it is 20 ft from the battery to the unit. Get equal lengths of wires (I use red and black) 40 ft long. Tie them together at each end. Loop one end over something so it will stay there. Make a hook out of something like a piece of wire clothes hanger and put it in your cordless drill. Go to the other end, hook it in the wire, pull the wires tight, and while keeping the wires tight turn the drill on. You will notice as the wire twists it keeps getting shorter and shorter. Stop when it gets to 20 ft and you are done. Keep in mind the more twists the better but the more wire you will need.

**Cane Pole** · 01-14-2012, 06:00 PM

Yes. By all means do this and save headaches. I just completed a new version of the Ipilot transfer box for the V2 (for the ones that were converted that did not have auto pilot).

Notice the white/black leads are twisted. One set is for power, the other is for signal. I incorporate this technique Bill speaks of every chance I get.

You can read the benefits of twisted pairs on Wikipedia. Gooogle it up.

**crappiemax** · 01-14-2012, 09:11 PM

So when I make my run from the fuse box at the console to the HDS unit on the bow I should run twisted wires (red/black).
Should I also do this with the wires running from the TM batteries to the TM plug?

**Cane Pole** · 01-14-2012, 10:24 PM

Originally Posted by crappiemax

So when I make my run from the fuse box at the console to the HDS unit on the bow I should run twisted wires (red/black).
Should I also do this with the wires running from the TM batteries to the TM plug?

Molded parallel power pair (like speaker wires) is supposed to be effective also, but I have observed more robot servo power and control cables using twisted pairs.

If you run single conductors (seperate black and red wires), then twist them.

**kosmo** · 01-15-2012, 01:11 AM

Would wire diameter make difference

**Barnacle Bill** · 01-15-2012, 08:40 AM

Originally Posted by kosmo

Would wire diameter make difference

No but it would be very hard to do this with heavy gauge wire like used for trolling motor power. You could put some twists in it by hand which would help. Like I said, the more the better.

**rnvinc** · 01-15-2012, 12:26 PM

Originally Posted by Cane Pole

Molded parallel power pair (like speaker wires) is supposed to be effective also, but I have observed more robot servo power and control cables using twisted pairs.

If you run single conductors (seperate black and red wires), then twist them.

Twist the red (+) and black(-) together....??

Or run 2 red (+) twisted together ...and separately run 2 black (-) twisted together...??

Rickie

**Barnacle Bill** · 01-15-2012, 01:12 PM

Originally Posted by rnvinc

Twist the red (+) and black(-) together....??

Or run 2 red (+) twisted together ...and separately run 2 black (-) twisted together...??

Rickie

Red and black. You want the pos and neg twisted together,

**Cane Pole** · 01-15-2012, 02:13 PM

Bill, you oughta link this thread to the emi sticky. Might help someone.

**crappiemax** · 01-15-2012, 02:38 PM

Originally Posted by Cane Pole

Bill, you oughta link this thread to the emi sticky. Might help someone.

I was thinking the same thing. I know this stuff has already helped me.

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