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Today's Topics:
1. Re: How much twist to put in wires to avoid interference?
(Clay and Carly Dunsworth)
2. Re: How much twist to put in wires to avoid interference?
(Bob Finch)
3. Re: How much twist to put in wires to avoid interference?
(Bob Finch)
4. Re: How much twist to put in wires to avoid interference?
(Bdale Garbee)
5. Re: How much twist to put in wires to avoid interference?
(David W. Schultz)
6. Re: How much twist to put in wires to avoid interference?
(Will Marchant)
----------------------------------------------------------------------
Message: 1
Date: Sun, 6 Dec 2020 14:05:02 -0600
From: Clay and Carly Dunsworth <[email protected]>
To: Altus Metrum <[email protected]>
Subject: Re: [altusmetrum] How much twist to put in wires to avoid
interference?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
When ?twisting? wires if found more twists are required to keep them together,
but if you look in twisted pair like M27500 much less are used. Ethernet and
canbus wires use more twisting. Shielded wire is pretty cheap to really
expensive, but that?s what I?m going to start using in the future. Just drain
the shields at a common ground. The cheaper M27500 is super available, and
fairly cheap.
On Dec 6, 2020, at 12:36, Will Marchant <[email protected]> wrote:
?Hi Folks:
Any "rules of thumb" about how much twisting to do of the various avionics
wires?
One turn per inch? More? Less?
Thanks in advance for any advice!
Happy holidays,
Will
--
Will Marchant, KW4WZ
[email protected]
http://www.spaceflightsoftware.com/will/
_______________________________________________
altusmetrum mailing list
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http://lists.gag.com/mailman/listinfo/altusmetrum
------------------------------
Message: 2
Date: Sun, 6 Dec 2020 14:10:26 -0700
From: Bob Finch <[email protected]>
To: Altus Metrum <[email protected]>
Subject: Re: [altusmetrum] How much twist to put in wires to avoid
interference?
Message-ID:
<CAASHNdW4Fs7dDHKAt-Wp1Ga2ppZAq3J2L+z=q8z6bfal+fr...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Hey Will;
If you place groups of wires together...twist them as "pairs"
separately, i.e. B+ and B- (ground) together, and each pair of signal
+ and signal - (charge firing) together, and so forth. IDEALLY if you
then are forced to place these pairs adjacent to one another AND they
have a slightly different twist "rate" (amount of twist per
"unit-of=-measure") things will be as good as you can get.
("Crosstalk" between pairs will be minimal as you can make it.)
In the confines of a "electronics bay" this may seem a lot more
theoretical than useful, but it forms good engineering practice, and
ignoring the above rules completely can contribute to an "ebay cato".
How so:
When so twisted the wires can "take shape" so that the
printed-circuit-board can be held in place by the wiring alone. So
when the brunt of excessive g forces breaks the plastic screws you
used for mounting (I know, everyone is a perfect flyer, so taking
"hard landings" into account may seem "excessive".....grin.), you now
have a chance of recovering a working unit....... !! (Ask me how I
know.....er, um, another time please !)
Anyways, my input......hope it helps you fiqure this out.
Fly high, fly fast, fly safe....not nec. in that order.
VERY best regards;
Baab F.
P.S... Shielding is not as useful as twisting on "balanced" circuits
when considering coupling between each (non-coaxial) wire (or circuit)
-pair, This is due to the lack of a third (tertiary) path on these
two-wire circuits.
On Sun, Dec 6, 2020 at 11:36 AM Will Marchant
<[email protected]> wrote:
Hi Folks:
Any "rules of thumb" about how much twisting to do of the various
avionics wires?
One turn per inch? More? Less?
Thanks in advance for any advice!
Happy holidays,
Will
--
Will Marchant, KW4WZ
[email protected]
http://www.spaceflightsoftware.com/will/
_______________________________________________
altusmetrum mailing list
[email protected]
http://lists.gag.com/mailman/listinfo/altusmetrum
------------------------------
Message: 3
Date: Sun, 6 Dec 2020 14:14:18 -0700
From: Bob Finch <[email protected]>
To: Altus Metrum <[email protected]>
Subject: Re: [altusmetrum] How much twist to put in wires to avoid
interference?
Message-ID:
<caashndu7svfttmioewp7watun+94s9pzwgh49ampclxy8-u...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
O.K....P.P.S. (And more to the point);
I twist the wires together as tightly as I can, and then a bit less on
the next pair, and so forth. I try to make sure that each pair is
twisted tightly enough to allow the board/unit in question to stand up
using just these wire pairs and then mount the board with plastic
"hardware".
On Sun, Dec 6, 2020 at 2:10 PM Bob Finch <[email protected]> wrote:
Hey Will;
If you place groups of wires together...twist them as "pairs"
separately, i.e. B+ and B- (ground) together, and each pair of signal
+ and signal - (charge firing) together, and so forth. IDEALLY if you
then are forced to place these pairs adjacent to one another AND they
have a slightly different twist "rate" (amount of twist per
"unit-of=-measure") things will be as good as you can get.
("Crosstalk" between pairs will be minimal as you can make it.)
In the confines of a "electronics bay" this may seem a lot more
theoretical than useful, but it forms good engineering practice, and
ignoring the above rules completely can contribute to an "ebay cato".
How so:
When so twisted the wires can "take shape" so that the
printed-circuit-board can be held in place by the wiring alone. So
when the brunt of excessive g forces breaks the plastic screws you
used for mounting (I know, everyone is a perfect flyer, so taking
"hard landings" into account may seem "excessive".....grin.), you now
have a chance of recovering a working unit....... !! (Ask me how I
know.....er, um, another time please !)
Anyways, my input......hope it helps you fiqure this out.
Fly high, fly fast, fly safe....not nec. in that order.
VERY best regards;
Baab F.
P.S... Shielding is not as useful as twisting on "balanced" circuits
when considering coupling between each (non-coaxial) wire (or circuit)
-pair, This is due to the lack of a third (tertiary) path on these
two-wire circuits.
On Sun, Dec 6, 2020 at 11:36 AM Will Marchant
<[email protected]> wrote:
Hi Folks:
Any "rules of thumb" about how much twisting to do of the various
avionics wires?
One turn per inch? More? Less?
Thanks in advance for any advice!
Happy holidays,
Will
--
Will Marchant, KW4WZ
[email protected]
http://www.spaceflightsoftware.com/will/
_______________________________________________
altusmetrum mailing list
[email protected]
http://lists.gag.com/mailman/listinfo/altusmetrum
------------------------------
Message: 4
Date: Sun, 06 Dec 2020 18:59:30 -0700
From: Bdale Garbee <[email protected]>
To: Will Marchant <[email protected]>,
[email protected]
Subject: Re: [altusmetrum] How much twist to put in wires to avoid
interference?
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
Will Marchant <[email protected]> writes:
Any "rules of thumb" about how much twisting to do of the various
avionics wires?
In practice, it turns out the actual twist rate isn't critical.
When I'm twisting by hand in random hotel rooms, I shoot for at least a
couple turns per inch. But, a "pro tip", clamping one end of the two
conductors, then putting the other end in a cordless variable speed
drill's chuck is a slick way to get nice even twisting and more twists
per inch. I'll do a few feet this way, then cut suitable lengths for
each of the things I need as I build an av-bay.
Oh, and since people ask, I like 22 AWG stranded with PVC insulation
when wiring up my ebays. Your mileage may vary...
Bdale
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Message: 5
Date: Sun, 6 Dec 2020 21:02:59 -0600
From: "David W. Schultz" <[email protected]>
To: [email protected]
Subject: Re: [altusmetrum] How much twist to put in wires to avoid
interference?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
On 12/6/20 12:36 PM, Will Marchant wrote:
Hi Folks:
Any "rules of thumb" about how much twisting to do of the various
avionics wires?
It depends. The goal of the twist is to have the magnetic field cancel
out so the twist rate depends an how the field varies. The field should
be reasonably constant from one twist to the next. In practice we just
don't have that much in the way of magnetic fields.
But I have this spool of 24AWG STP that is tend to use just because I
have it.
