AoE x-Chapters - 1x.1 Wire-&-Connectors

[George Herold]

On Monday, August 5, 2019 at 2:23:12 PM UTC-4, Phil Hobbs wrote:

On 8/5/19 8:32 AM, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts things off, by
dealing with wire and connectors. Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1




Wow, an embarrassment of riches today.

One other thing about Teflon wire is that it's a royal pain to strip
using dikes. Irradiated PVC can be stripped in one motion with a pair
of sharp cutters.

Prepreg isn't copper coated--the plating is on the cores. The cores are
pre-cured, but the prepreg flows during lamination.

It's usually best to ask the board house what width to use for a 50-ohm
line. FR-4 varies fairly widely in dielectric constant, and they know
what brand they're using.

PCB propagation is faster on surface levels than inside, because the
effective refractive index is ~sqrt((1+epsilon)/2) = 1.68 vs
sqrt(epsilon) = 2.1.

I'd really like a couple more sentences on FFC/FPC cables. We use them
all over the place, and they're great. The 1-mm ones are much less
likely than the 0.5s to short out if you put them in a bit crooked. The
jumpers you can buy are all made by taking wire and rolling it out flat,
so they can carry lots of current, but if you get them made from plated
Kapton, they are the undisputed champs at getting wires on and off cold
plates.

Twisted pair helps crosstalk if you're really driving and receiving
differentially, i.e. the odd mode, using Ethernet transformers, for
instance. The even mode couples back and forth very easily.

I didn't know about the big-box effect. Cool!

Connector catalogues are full of things that they don't actually stock
but would be happy to make for you if you order 100k pieces. Always
check for ample distributor stock before designing in any part, but
connectors _especially_.


You're _way_ too kind to the Black Magic folks. HoJo is completely up a
pole on the subject of ground currents, among many other things. He had
a video (since pulled down) on an electrostatic demo purporting to show
ground currents following under the traces, but ten seconds calculation
showed that his impedance levels were, like, six orders of magnitude
away from where inductance would make any difference. The "ground
plane" was made up of metal squares affixed to one side of a piece of
glass, with the traces on the other side. The twists and turns of the
"ground current" were governed entirely by corona discharge from the
corners of the squares in the regions of highest E field. Yet he was
giving this cockamamie magnetic explanation. The SNR of the Black Magic
books is no more than 3 dB IMO.

JL and I had a fun go-round here on that some years back--we were
competing to see if we could sell our copies to _somebody_.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

Ground currents are not a crazy idea, I've fixed some
'bad layout' done by someone else, by thinking about
the return current. (There are lotsa silly ideas
about ground)
GH

George H.

 

[Martin Riddle]

On 5 Aug 2019 05:32:08 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1

No 50-50-50 rule in the connector section?
<https://www.connector.com/gold-or-tin-versus-gold-and-tin/>
<https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandments.pdf>

Cheers

 

[George Herold]

On Monday, August 5, 2019 at 2:23:12 PM UTC-4, Phil Hobbs wrote:

On 8/5/19 8:32 AM, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts things off, by
dealing with wire and connectors. Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1




Wow, an embarrassment of riches today.

One other thing about Teflon wire is that it's a royal pain to strip
using dikes.

Huh, Phil, I've been meaning to ask this for a while... but it
seems to me you need a good pair of dikes, with sharp holes for each
wire size. I've got these "paladin" strippers.. but I think someone
bought them out.
Can I send you some good strippers for your Birthday? :^)

George H.
Irradiated PVC can be stripped in one motion with a pair

of sharp cutters.

Prepreg isn't copper coated--the plating is on the cores. The cores are
pre-cured, but the prepreg flows during lamination.

It's usually best to ask the board house what width to use for a 50-ohm
line. FR-4 varies fairly widely in dielectric constant, and they know
what brand they're using.

PCB propagation is faster on surface levels than inside, because the
effective refractive index is ~sqrt((1+epsilon)/2) = 1.68 vs
sqrt(epsilon) = 2.1.

I'd really like a couple more sentences on FFC/FPC cables. We use them
all over the place, and they're great. The 1-mm ones are much less
likely than the 0.5s to short out if you put them in a bit crooked. The
jumpers you can buy are all made by taking wire and rolling it out flat,
so they can carry lots of current, but if you get them made from plated
Kapton, they are the undisputed champs at getting wires on and off cold
plates.

Twisted pair helps crosstalk if you're really driving and receiving
differentially, i.e. the odd mode, using Ethernet transformers, for
instance. The even mode couples back and forth very easily.

I didn't know about the big-box effect. Cool!

Connector catalogues are full of things that they don't actually stock
but would be happy to make for you if you order 100k pieces. Always
check for ample distributor stock before designing in any part, but
connectors _especially_.


You're _way_ too kind to the Black Magic folks. HoJo is completely up a
pole on the subject of ground currents, among many other things. He had
a video (since pulled down) on an electrostatic demo purporting to show
ground currents following under the traces, but ten seconds calculation
showed that his impedance levels were, like, six orders of magnitude
away from where inductance would make any difference. The "ground
plane" was made up of metal squares affixed to one side of a piece of
glass, with the traces on the other side. The twists and turns of the
"ground current" were governed entirely by corona discharge from the
corners of the squares in the regions of highest E field. Yet he was
giving this cockamamie magnetic explanation. The SNR of the Black Magic
books is no more than 3 dB IMO.

JL and I had a fun go-round here on that some years back--we were
competing to see if we could sell our copies to _somebody_.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Tim Williams]

<klaus.kragelund@gmail.com> wrote in message
news:5c330dff-88c9-49c8-bec7-791abba79a50@googlegroups.com...

Avoid SMD connectors, they rip off the traces of the PCB

Sorta. I don't have a problem with SMTs for board-to-board and light
internal cabling. The key enabler being that it's not fiddled with by the
user, and that it's not bearing a lot of force especially during vibration

Your perspective may be skewed even further in the direction of super high
reliability, like, multiple decades. The above is adequate for ~1 decade
automotive customers. Consumer junk of course uses SMT-exposed-to-user
connectors all the time, and barely get a year.

So, some discussion on reliability versus technology versus application
might be worthwhile. There can be no one answer!

For high quality connections, use pressfit, which also removes the leaded
wave solder process

Heh... if the pins mate properly; Joerg has a story about that.

Speaking of... come to think of it, they're usually tin plated pins, aren't
they? In a ENIG hole, say? Isn't that prone to fretting?

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[Phil Hobbs]

On 8/5/19 8:50 PM, George Herold wrote:

On Monday, August 5, 2019 at 2:23:12 PM UTC-4, Phil Hobbs wrote:
On 8/5/19 8:32 AM, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts things off, by
dealing with wire and connectors. Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1




Wow, an embarrassment of riches today.

One other thing about Teflon wire is that it's a royal pain to strip
using dikes.
Huh, Phil, I've been meaning to ask this for a while... but it
seems to me you need a good pair of dikes, with sharp holes for each
wire size. I've got these "paladin" strippers.. but I think someone
bought them out.
Can I send you some good strippers for your Birthday? :^)

I'll be 60 late next month, so a few strippers would be apropos--just
don't tell my wife. Maybe they could jump out of a cake.

I generally use Xcelite flush cutters, which are far better than the
usual axe-blade dikes. I also have the usual spade lug crimper / bolt
cutter/ wire stripper tools. I don't like the big clunky strippers that
mechanically sense the insulation and adjust their blades accordingly--I
just want insulation to do as it's damn well told, and Teflon doesn't,
in so many, many ways.

Cheers

Phil Hobbs

George H.
Irradiated PVC can be stripped in one motion with a pair
of sharp cutters.

Prepreg isn't copper coated--the plating is on the cores. The cores are
pre-cured, but the prepreg flows during lamination.

It's usually best to ask the board house what width to use for a 50-ohm
line. FR-4 varies fairly widely in dielectric constant, and they know
what brand they're using.

PCB propagation is faster on surface levels than inside, because the
effective refractive index is ~sqrt((1+epsilon)/2) = 1.68 vs
sqrt(epsilon) = 2.1.

I'd really like a couple more sentences on FFC/FPC cables. We use them
all over the place, and they're great. The 1-mm ones are much less
likely than the 0.5s to short out if you put them in a bit crooked. The
jumpers you can buy are all made by taking wire and rolling it out flat,
so they can carry lots of current, but if you get them made from plated
Kapton, they are the undisputed champs at getting wires on and off cold
plates.

Twisted pair helps crosstalk if you're really driving and receiving
differentially, i.e. the odd mode, using Ethernet transformers, for
instance. The even mode couples back and forth very easily.

I didn't know about the big-box effect. Cool!

Connector catalogues are full of things that they don't actually stock
but would be happy to make for you if you order 100k pieces. Always
check for ample distributor stock before designing in any part, but
connectors _especially_.


You're _way_ too kind to the Black Magic folks. HoJo is completely up a
pole on the subject of ground currents, among many other things. He had
a video (since pulled down) on an electrostatic demo purporting to show
ground currents following under the traces, but ten seconds calculation
showed that his impedance levels were, like, six orders of magnitude
away from where inductance would make any difference. The "ground
plane" was made up of metal squares affixed to one side of a piece of
glass, with the traces on the other side. The twists and turns of the
"ground current" were governed entirely by corona discharge from the
corners of the squares in the regions of highest E field. Yet he was
giving this cockamamie magnetic explanation. The SNR of the Black Magic
books is no more than 3 dB IMO.

JL and I had a fun go-round here on that some years back--we were
competing to see if we could sell our copies to _somebody_.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 8/5/19 9:05 PM, George Herold wrote:

On Monday, August 5, 2019 at 2:23:12 PM UTC-4, Phil Hobbs wrote:
On 8/5/19 8:32 AM, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts things off, by
dealing with wire and connectors. Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1




Wow, an embarrassment of riches today.

One other thing about Teflon wire is that it's a royal pain to strip
using dikes. Irradiated PVC can be stripped in one motion with a pair
of sharp cutters.

Prepreg isn't copper coated--the plating is on the cores. The cores are
pre-cured, but the prepreg flows during lamination.

It's usually best to ask the board house what width to use for a 50-ohm
line. FR-4 varies fairly widely in dielectric constant, and they know
what brand they're using.

PCB propagation is faster on surface levels than inside, because the
effective refractive index is ~sqrt((1+epsilon)/2) = 1.68 vs
sqrt(epsilon) = 2.1.

I'd really like a couple more sentences on FFC/FPC cables. We use them
all over the place, and they're great. The 1-mm ones are much less
likely than the 0.5s to short out if you put them in a bit crooked. The
jumpers you can buy are all made by taking wire and rolling it out flat,
so they can carry lots of current, but if you get them made from plated
Kapton, they are the undisputed champs at getting wires on and off cold
plates.

Twisted pair helps crosstalk if you're really driving and receiving
differentially, i.e. the odd mode, using Ethernet transformers, for
instance. The even mode couples back and forth very easily.

I didn't know about the big-box effect. Cool!

Connector catalogues are full of things that they don't actually stock
but would be happy to make for you if you order 100k pieces. Always
check for ample distributor stock before designing in any part, but
connectors _especially_.


You're _way_ too kind to the Black Magic folks. HoJo is completely up a
pole on the subject of ground currents, among many other things. He had
a video (since pulled down) on an electrostatic demo purporting to show
ground currents following under the traces, but ten seconds calculation
showed that his impedance levels were, like, six orders of magnitude
away from where inductance would make any difference. The "ground
plane" was made up of metal squares affixed to one side of a piece of
glass, with the traces on the other side. The twists and turns of the
"ground current" were governed entirely by corona discharge from the
corners of the squares in the regions of highest E field. Yet he was
giving this cockamamie magnetic explanation. The SNR of the Black Magic
books is no more than 3 dB IMO.

JL and I had a fun go-round here on that some years back--we were
competing to see if we could sell our copies to _somebody_.


Ground currents are not a crazy idea, I've fixed some
'bad layout' done by someone else, by thinking about
the return current. (There are lotsa silly ideas
about ground)

Ground currents are a thing, I agree, but HoJo knows a lot less about
them than he lets on. A PCB has a lot of fast distributed capacitance,
which covers a multitude of sins.

Star grounds in fast mixed signal systems, now _that's_ a disaster.

Cheers

Phil Hobbs

 

[John Larkin]

On Mon, 5 Aug 2019 13:03:34 -0700 (PDT), klaus.kragelund@gmail.com
wrote:

On Monday, 5 August 2019 21:52:56 UTC+2, klaus.k...@gmail.com wrote:
On Monday, 5 August 2019 16:20:18 UTC+2, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1


Some comments:

For leaded, you can also use Pin in Paste and laser soldering.

Also instead of wave, you can use selective soldering, which is more controlled than a broad wave

For connectors, fretting corrosion is the real killer.

Use decent amount of gold plating, and use the same plating for both plug and socket. Otherwise it makes no sense to add gold.

Also, too much gold is not better either. Just a waste of money

For fretting, to avoid it all together, use a bleading current so that the connection is always "current" driven at at least mA level. Reduces effects of fretting corrosion dramatically

For connectors, between 2 PCBs, use a floating connection. One PCB locked, the other able to float. That way mating is secure, and thermal expansion cycles does not wear out the connection

For the ac resistances, skin effect, maybe mention dowells equation, mostly used for transformers. Just a couple of layers in a winding can increase the DC resistance 100 fold

Cheers

Klaus

Oh, and derate the connections to 50% current. Power dissipation in connectors kill them. Use high dimension wires to the connector to pull the heat away from the connection point. About connection points, use pins that have more than just one touch point

Using multiple smallish parallel wires between connectors adds
ballasting resistance that equalizes pin currents.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Phil Hobbs]

On 8/5/19 4:01 PM, klaus.kragelund@gmail.com wrote:

On Monday, 5 August 2019 21:52:56 UTC+2, klaus.k...@gmail.com wrote:
On Monday, 5 August 2019 16:20:18 UTC+2, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1


Some comments:

For leaded, you can also use Pin in Paste and laser soldering.

Also instead of wave, you can use selective soldering, which is more controlled than a broad wave

For connectors, fretting corrosion is the real killer.

Use decent amount of gold plating, and use the same plating for both plug and socket. Otherwise it makes no sense to add gold.

Also, too much gold is not better either. Just a waste of money

For fretting, to avoid it all together, use a bleading current so that the connection is always "current" driven at at least mA level. Reduces effects of fretting corrosion dramatically

For connectors, between 2 PCBs, use a floating connection. One PCB locked, the other able to float. That way mating is secure, and thermal expansion cycles does not wear out the connection

For the ac resistances, skin effect, maybe mention dowells equation, mostly used for transformers. Just a couple of layers in a winding can increase the DC resistance 100 fold

Cheers

Klaus

Avoid SMD connectors, they rip off the traces of the PCB

Depends. SMD panel/bulkhead connectors, I agree in general, but there
are some that grip the board edge pretty well. For moderate
frequencies, I mostly use cast-zinc BNCs that have survived the stomp
test: put the unit in a bench vise, attach a BNC cable you never want to
see again, let it droop on the floor, and stomp on it. The cable should
fail at the connector, and the board should be fine.

Minimum standard student-proofing.

For high quality connections, use pressfit, which also removes the leaded wave solder process

For best possible connections use gat tight connections. Press fit, crimping, splicing, wire wrap

You like wire wrap better than soldering?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[John Larkin]

On Mon, 05 Aug 2019 21:02:26 -0400, Martin Riddle
<martin_ridd@verizon.net> wrote:

On 5 Aug 2019 05:32:08 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1

No 50-50-50 rule in the connector section?
https://www.connector.com/gold-or-tin-versus-gold-and-tin/
https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandments.pdf

Cheers

Tin whiskers.

https://www.dropbox.com/s/h1xfznelskqe3rr/DSC06635.JPG?raw=1


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Tim Williams]

1x.1.4.A: Free resistance? That sounds useful! ...Ah, may want to add a
note that copper's tempco is _deplorable_, to discourage that creative use
(or, at least, make it understood that your use will have to be a bit more
creative in turn).

Hanging parenthesis in 1x.1.5 (instrumentation cable).

Worth noting that 1x.1.6.A is doing the same thing that's already been
covered: impedance. Zo goes as the ratio of inductance and capacitance, Zo
= sqrt(L/C). And if you know the velocity factor, mu_r or e_r, you know the
L and C of the transmission line. So in the same way that you can know or
look up trace impedances, and their inductance or capcaitance, at a glance,
so too it works for cables.

Or put another way, it seems odd to me, or unfair even, that there's a
subsection on inductance, but not capacitance, or not both in general
(impedance).

May be worth noting that, even though multiconductor cable isn't intended
for transmission line purposes, it still has some impedance; might be an
opportunity to emphasize why it's generally undesirable to do so (i.e.,
coupling).

Give or take whatever's referred to the transmission line section proper, of
course (appendix H?).

Footnote 16 -- to be even more precise, it's a boundary condition and wave
problem, like all EM problems, I suppose; in an infinite cylinder the
solutions are not actually exponential, but Bessel functions. For this
reason, you can get current density going to zero at some depth, then
popping up below there /in the opposite direction/! (delta is still the
figure of proportion that feeds the Bessel function, so it's still close
enough to exponential for the engineer's hand-wave.) Not very useful for
cabling, but it's interesting for industrial induction heating anyway.

Likewise, for flat plates, you get interference from the waves penetrating
the front and back sides (if currents are arranged to flow there; think
coplanar waveguide but with copper thickness way higher than width?),
leading to nulls and opposite peaks towards the center.

The pure exponential case is only for a semi-infinite block, of course; for
d >> delta, the geometry doesn't really matter, and we can still use this
figure. It's just that weird things happen for d ~ delta.

Anyway.

Oh, and this is alluded to later (footnote 19), nevermind.
Subsection 7 and 8: well, you beat me to it I see. :^)

1x.1.10 -- Digi-Key should be hyphenated I think?

"DC power entry" connectors -- usually called barrel connectors? Also,
can't figure out the "blue hexagon".

I'm fond of Molex SL and KK series headers for general connector-to-board
use, or pluggable headers like OSTOQ025450 for higher currents/voltages. MT
as noted is fine too, but beware of the reliability of IDC headers. (IDC
ribbons seem alright, or at least, there aren't many better termination
alternatives so you're kind of stuck with it; but I wonder if
IDC-to-loose-wires is worse than to ribbon-of-wires?)

M12 and such circular connectors are very popular for industry (especially
where IP67 and such ratings are desirable), if a bit pricey for general
application; not to mention the notoriously expensive, finely crafted Turck
and Lemo types.

Interesting to plot banana jacks for transmission; but, was this at 50 ohms?
I wonder how they do in, say, a 200 or 300 ohm system. And, balanced,
obviously. Might be the perfect connector for twin lead, eh? (Checked the
reference but I don't see this data on it.) Heh, nevermind the mechanical
(mere friction fit, no retention) or environmental limitations... :^)

Cheers!
Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

"Winfield Hill" <winfieldhill@yahoo.com> wrote in message
news:qi97k80st2@drn.newsguy.com...

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1


--
Thanks,
- Win

 

[Tim Williams]

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:qian03$9nf$2@gioia.aioe.org...

Star grounds in fast mixed signal systems, now _that's_ a disaster.

The worst part about it is, star grounding _is_ excellent, but it has to be
the correct topology.

Sawing up grounds, ain't it. Routing signals between spokes, ain't it.

Placing signal grounds together, routing signals with ground, in a star
fashion, is the way to be.

Classic example, the ground loop currents in an SMPS section create a
voltage drop across the area; so, route the input and output terminals off
to a single side (as opposed to straight across), where they can exit over
the same common ground area. Place your filter here. CM noise is *gone*.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[Martin Riddle]

On Mon, 05 Aug 2019 19:07:03 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

On Mon, 05 Aug 2019 21:02:26 -0400, Martin Riddle
martin_ridd@verizon.net> wrote:

On 5 Aug 2019 05:32:08 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1

No 50-50-50 rule in the connector section?
https://www.connector.com/gold-or-tin-versus-gold-and-tin/
https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandments.pdf

Cheers

Tin whiskers.

https://www.dropbox.com/s/h1xfznelskqe3rr/DSC06635.JPG?raw=1

True, But those great Meanwell power supplies come with Tin molex
headers.

Cheers

 

[John Larkin]

On Mon, 5 Aug 2019 22:02:38 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message
news:qian03$9nf$2@gioia.aioe.org...

Star grounds in fast mixed signal systems, now _that's_ a disaster.


The worst part about it is, star grounding _is_ excellent, but it has to be
the correct topology.

Sawing up grounds, ain't it. Routing signals between spokes, ain't it.

Placing signal grounds together, routing signals with ground, in a star
fashion, is the way to be.

Classic example, the ground loop currents in an SMPS section create a
voltage drop across the area; so, route the input and output terminals off
to a single side (as opposed to straight across), where they can exit over
the same common ground area. Place your filter here. CM noise is *gone*.

Tim

Signal integrity is easy. PCB layer 2 is solid ground plane. Bolt it,
and grounded connector shells, to the metal box in as many places as
possible.

Cable shields to the box ditto.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Tim Williams]

"John Larkin" <jjlarkin@highlandtechnology.com> wrote in message
news:cavhkeppudjiempknhs0jb84jpkau3sgo8@4ax.com...

Signal integrity is easy. PCB layer 2 is solid ground plane. Bolt it,
and grounded connector shells, to the metal box in as many places as
possible.

Cable shields to the box ditto.

Not really. Suppose there's a huge noisy inverter in the box. Ground loop
currents once again. Cables simply tied "shields to the box", and PCB
"bolt[ed] ... to the metal box", draws those currents into both. Now your
precision ADCs are all reading trash.

But with visibility to where the currents are flowing, or with a
star-grounding scheme, those loop currents stay separate. Say the
connectors are clustered on a front panel, shields grounded to it. That
keeps outside noise out, good. Collect the interior cables (which are still
all grounded to the same point, preferably as coaxially as possible, no
weedy wire links), and bundle them into a single harness. Ferrite beads as
needed. They go over to the PCB, which no longer needs chassis ground at
all.

Or do the brute-force method and use welded chassis compartments to keep the
bignasty away from the quietstuff. Cost doesn't much matter in your test
equipment, but it's a very real tradeoff in production. Production even
likes to avoid metal if they can...

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

 

[John Robertson]

On 2019/08/05 2:19 p.m., klaus.kragelund@gmail.com wrote:

On Monday, 5 August 2019 22:47:20 UTC+2, John Robertson wrote:
On 2019/08/05 5:32 a.m., Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1



On page 17 where you start talking about connectors you state:

“The most unreliable components in any electronic system will be the
following (worst first): 1. Connectors and cables. 2. Switches. 3.
Potentiometers and trimmers.”

My experience with arcade games and monitor (tube and LED/LCD) repairs
would fit electrolytic capacitors between #2 and #3. Or possibly even as
#2...

Is that not your experience too when repairing defective equipment?

Thanks for proving a draft to read, it is informative and I enjoy your
style of humour, which makes for a more readable manual.

John :-#)#

Experience from pump industry, electrolytics are number 1 field failure failure item, when mechanics is omitted

I guess mechanics is the point here - his first three items are all
mechanical devices. I still find mechanical switches to be somewhat more
reliable than electrolytic caps.

John :-#)#

 

[John Robertson]

On 2019/08/05 1:01 p.m., klaus.kragelund@gmail.com wrote:

On Monday, 5 August 2019 21:52:56 UTC+2, klaus.k...@gmail.com wrote:
On Monday, 5 August 2019 16:20:18 UTC+2, Winfield Hill wrote:
Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1


Some comments:

For leaded, you can also use Pin in Paste and laser soldering.

Also instead of wave, you can use selective soldering, which is more controlled than a broad wave

For connectors, fretting corrosion is the real killer.

Use decent amount of gold plating, and use the same plating for both plug and socket. Otherwise it makes no sense to add gold.

Also, too much gold is not better either. Just a waste of money

For fretting, to avoid it all together, use a bleading current so that the connection is always "current" driven at at least mA level. Reduces effects of fretting corrosion dramatically

For connectors, between 2 PCBs, use a floating connection. One PCB locked, the other able to float. That way mating is secure, and thermal expansion cycles does not wear out the connection

For the ac resistances, skin effect, maybe mention dowells equation, mostly used for transformers. Just a couple of layers in a winding can increase the DC resistance 100 fold

Cheers

Klaus

Avoid SMD connectors, they rip off the traces of the PCB

For high quality connections, use pressfit, which also removes the leaded wave solder process

For best possible connections use gat tight connections. Press fit, crimping, splicing, wire wrap

I can't recommend insulation displacement connections - after about ten
to twenty years they start to fail due to (assumption here on my part)
gradual displacement of the insulation leading to the wire strands
losing their stiffness and the connection becomes iffy as the strands
displace.

John :-#)#

 

[David Nadlinger]

On 05.08.19 1:32 PM, Winfield Hill wrote:

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1

Regarding that circled capital L in footnote 21: Litzendraht as a German
noun should indeed be uppercase, so the current footnote is correct
(potential disagreements about capitalisation of the loanword in the
body copy notwithstanding).

— David

 

[piglet]

On 06/08/2019 02:58, Phil Hobbs wrote:

I'll be 60 late next month, so a few strippers would be apropos--just
don't tell my wife. Maybe they could jump out of a cake.

I generally use Xcelite flush cutters, which are far better than the
usual axe-blade dikes.  I also have the usual spade lug crimper / bolt
cutter/ wire stripper tools.  I don't like the big clunky strippers that
mechanically sense the insulation and adjust their blades accordingly--I
just want insulation to do as it's damn well told, and Teflon doesn't,
in so many, many ways.

I'll be 60 a few months after you. I already have my strippers! They're
Teledyne thermal and cope fine with Teflon and dialled back with any
other insulation devised.

piglet

 

[Clive Arthur]

On 06/08/2019 03:07, John Larkin wrote:

On Mon, 05 Aug 2019 21:02:26 -0400, Martin Riddle
martin_ridd@verizon.net> wrote:

On 5 Aug 2019 05:32:08 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

Here's a DRAFT copy of x-Chapter 1x.1, which starts
things off, by dealing with wire and connectors.
Comments and corrections please.

https://www.dropbox.com/s/kz335xwvl5v8gie/1x.1_Wire-%26-Connectors_DRAFT.pdf?dl=1

No 50-50-50 rule in the connector section?
https://www.connector.com/gold-or-tin-versus-gold-and-tin/
https://www.ramoem.com/uploads/4/4/0/7/44075859/tin_commandments.pdf

Cheers

Tin whiskers.

https://www.dropbox.com/s/h1xfznelskqe3rr/DSC06635.JPG?raw=1

Tinned Whiskas...

https://imgur.com/oI3MVJT

Cheers
--
Clive

 

[whit3rd]

On Monday, August 5, 2019 at 6:58:20 PM UTC-7, Phil Hobbs wrote:

On 8/5/19 8:50 PM, George Herold wrote:
On Monday, August 5, 2019 at 2:23:12 PM UTC-4, Phil Hobbs wrote:

One other thing about Teflon wire is that it's a royal pain to strip
using dikes.

I generally use Xcelite flush cutters, which are far better than the
usual axe-blade dikes. I ...
just want insulation to do as it's damn well told, and Teflon doesn't,
in so many, many ways.

Did a few fine-wire end preps, with 40 gage gold in PTFE jacket.
Scalpel, microscope, patience. And some extra wire length, just in case.