masonman

Why are some digital servo wires twisted or braided? Why are some extensions twisted or braided? Is there any type of advantage to this compared to the flat type?

bunsen

Hi

The main reason, I believe, that servo wires are twisted is that it acts like a unshielded twisted pair, even though there are three wires which is a twisted triad, which minimizes induced voltages on the servo lines from RF pickup.

In a perfect world with a twisted pair with ground and signal twisted together, it gives you a nominal 100 ohm or so impedance based on wire size and twists/inch, when there is RF pickup it gets picked up equally on both wires which gets presented as a common mode signal to the receiver and hopefully has less effect then if it was on only one wire.

What I do when building extension cables is take the three wires and tie one end to a vise and chuck the other end(s) in a drill. Then run the drill at a slow speed and "twist' the wires.

One description is:
http://searchnetworking.techtarget.c...214167,00.html


Just my suggestion.

Ray

masonman

What is the advantage of doing this? Is it something that will be life or death for my airplane?

Tired Old Man

My Feedback: (1)

Hitec and some after market extension companies twist their wires. There was a thought some time back that twisting the servo wire "x" number of times in an inch would prevent rf feedback through long servo leads. Myself and others have used some mighty long leads that were not twisted and have never experienced the rf or glitch issues. All I use are standard high quality flat servo leads and extensions in planes up to 35% scale and there has never been an issue. Typically I only use extensions from Cermark since they use a silicone insulation that will not ever flame if they become too hot, use gold plated connector pins, and since they make extremely high quality products for many of the radio manufacturers. Prices are the best as well.

No worries whether the wires are twisted or flat, or if the two types are combined between a servo and an extensions. As long as you use good products you won't have a problem.

JPMacG

My Feedback: (2)

LOL... the old twisted vs flat debate. This is always good for a long heated agrument,, even among EMI/EMC professionals. My opinion, and this is contrary to most, is that it makes no difference. The important thing is that the wires be in close proximity, it does not matter wheter they are held that way by twisting or by bonding of their insulation.

There is an exception to my opinion above. That is the case where many wire pairs are bundled together in a common cable. Then there is a benefit to having each pair twisted.

masonman

Thanks for the feedback.