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

On Wed, 7 Aug 2019 01:22:30 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

upsidedown@downunder.com> wrote in message
newsjnkke5qbdius6qf4f8a6af8i62e7koag2@4ax.com...
But then you get induced [electric] currents corrupting your signal.

With standard 20 mA current loop driven from a 24 Vdc supply will
carry nearly 0.5 W signal power, thus a quite strong interference is
needed to disturb the signal.

Unless it's quite precise. Recently had a customer ask for 24-bit inputs.
Ended up with a precision burden resistor, channel mux, in-amp and a TI SPI
ADC.

That 24 bit is quite special requirement, since it is more than 7
decimal digits. That might be needed when measuring the weight of a
car and then something 1 gram on the same scale. In such cases the
sampling period can be quite long, such as 100 ms, which cancels some
of 50 Hz as well as 60 Hz interference.

Some high quality audio use 24 bit ADCs, but the real accuracy is
about 20 bits (120 dB SNR).

Going digital at the signal source helps a lot.

Noise floor looks close to what the datasheet claims, so that's good news
about my front end. CMRR isn't bad, is visible but of a similar magnitude
(~100 counts over the input range). And hey, resistor matching, what do you
expect. (I added functionality so they can measure VCM and calibrate it out
in software if they want. And yes, customer's handing software.)

Since the inputs are filtered and essentially unloaded (only the filter
caps, mux switch, and in-amp input leakages), the inputs float very nicely,
and can be biased (in the common mode) by a touch of the finger. There is
some sequential charge transfer between channels, due the mux.

They couldn't give me a hard commitment on what ground reference or
polarity* the 4-20mA channels might be, so I had to do this (your
traditional +/-15V AFE). It's a 24V system and they really would've rather
had a 30V range, but that gets harder and harder to pull off (not so hard
regarding precision amps, but analog switches?).

*In the sense that there are high-side and low-side drivers. In an ideal
world, these are on isolated circuits so it doesn't matter, but, you know.
But it's a current loop, right? We don't care about voltage, the current
cures all!...Right? (See what really happens here?)


Using twisted pairs .e.g. telephone cables also limits the induced
interference.

Yup, pretty nice. Unless there's a nick in the insulation and now you have
current leakage from one or the other line...


Current loops have been done with optoisolators for nearly half a
century, so you also get galvanic isolation for 'free'. Powering the
loop always from the transmitter side, the receiver can be passive
(an IR LED) so no ground potential issues between boxes.

Optos are terrible! Unstable gain, poor distortion, slow speed. Fine for
serial. Basically useless above say 8 ENOB, and a few megbits.

Using dual optos at the transmitting side helps, if the other opto is
used for feedback.

It is quite typical to use 12 bit ADCs with current loops, which gives
better than 0.1 % resolution. Few transducers are better than this, at
least repeatedly.

No free lunch. Use differential regardless.

Properly terminated RS-422 line is essentially a bipolar current loop.


It's also a bipolar voltage pair. "Properly terminated" being the key word
there. It is necessarily and simultaneously both! Concentrating on just
one is setting yourself up for edge cases in the other.

Tim

 

[Tim Williams]

<upsidedown@downunder.com> wrote in message
news:io1lke5e64kb0t9594g7td1r8sb3hq1f8l@4ax.com...

Have you looked at the current waveform of a simple old style six
pulse rectifier. ? It contains quite a lot of high harmonics. Current
requirements usually require some kind of PFC, for instance a 12 pulse
rectifier.

Doesn't even matter -- the harmonics don't extend that high. Well, they do,
but not because of rectification as such, but because of diode recovery.
That's usually in the low MHz range, and some volts in magnitude. A pain
for EMC, but nowhere near as violent as the other side...

(A phase controlled rectifier can get up there in amplitude. SCRs don't
switch all that fast, fractional microseconds maybe, so again, low MHz
harmonics; but the worst case magnitude is a step change of the full peak
line voltage.)

Then there are the PWM drive side, which should use shielded power
cables to the motor to reduce radiation, even if there are some filter
in at VFD output.

This. Or conduit more likely. But that can be hard to use. For which they
might opt for flexible conduit e.g. SealTite, which is supposed to be
grounded through the end fittings so it should be okay. But, maybe it
doesn't make such a good connection? (As it is, regular rigid conduit may
only make a few points of contact, with those setscrew-locked fittings.
Compression fittings should be excellent though.) Or someone forgets to use
metal and goes with plastic instead?

Or if it's not even grounded correctly, so, presumably the VFD has some
local RF grounding inside it (or all the same, the EMI just goes up the
mains conduit instead), but that's not been well-grounded to the output
conduit, and the loop between grounds ends up huge.

And that can happen easily in a normal industrial panel -- you install all
the components: fuses, terminal blocks, DIN rail, contactor, PSU, VFD, PLC,
on a common plate. You lift the plate into the panel and bolt it down.
It's only grounded to the panel itself through those bolts, and whatever
wires have been added. Maybe the paint wasn't properly scraped off the
panel and none of its mounts make ground? Then you'd be relying on the
galvanic ground -- some long piece of 12AWG spaghetti -- for RF ground.

If nothing else, all the wiring on such a panel is neatly tucked together
into raceways. It's not like you can run a conduit right up to the
DIN-mounted VFD. (How would you get the plate in or out?) So all your,
say, 24V or 4-20mA control signals get intimately mingled with those 360V
peak square waves.

It could still be routed in a responsible way, absolutely; you could add a
ground strap between the plate and the target conduit, keep the VFD output
cables independent from the other raceways, and routed along the plate and
ground strap. If mains is badly filtered, you can put a line filter right
beside the VFD (you can get DIN-mounted ones that ground through the DIN
clamp, not exactly perfect for RFI, but a damn good start on EMI), and then
you aren't so worried about the mains being routed wherever. And you could
use R+C or MOV or other snubbers across all the contacts: relays,
contactors, solenoids, whatever. But that's a degree of knowledge most
technicians don't have, so unless the panel was designed carefully by an
engineer first, it's unlikely your average industrial panel is built quite
so neatly.

So in short, it's no surprise that industrial environments can get god-awful
noisy.

And it's a good thing that stand-alone VFDs exist, with standard electrical
breakouts on the bottom, and hopefully good filtering and grounding, all
together in one package. Run conduits in and out, connect up your control
signals, and you're golden.

Still likely to be a few volts of noise floating around, but that's at least
tolerable to RS-485 and such (7V CM range). Now, that still sucks if you're
trying to do anything much quieter (say, scoping those serial lines), but
such is life.

Tim

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

 

[George Herold]

On Tuesday, August 6, 2019 at 10:38:31 PM UTC-4, Phil Hobbs wrote:

On 8/6/19 10:02 AM, George Herold wrote:
On Monday, August 5, 2019 at 9:58:20 PM UTC-4, 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:
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.

Well I've got a pair of these,
https://www.amazon.com/Greenlee-PA1118-GripP-Stripper-Cutter/dp/B0006BHHDQ
(I guess Grennlee bought Paladin tools) If you don't have something like that
then that's what's coming for your B-day. I see Amazon has a deal on two pairs,
(different wire sizes.) I don't think I can make 'em jump out of a cake. :^)

George h.

Very kind of you, but I'd never use them. (The ones that come out of
the cake though...nah, I'd never use those either.)

OK, just trying to help you find the right tool.
After a while pounding nails with the crescent* hammer gets old.

George h.
*Gessh googling there are a bunch of crescent wrenches with built in hammers...
who knew.

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 8/7/19 2:09 AM, upsidedown@downunder.com wrote:

On Tue, 6 Aug 2019 18:21:57 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 8/6/19 3:57 PM, upsidedown@downunder.com wrote:
On Tue, 6 Aug 2019 08:41:09 -0700 (PDT), Lasse Langwadt Christensen
langwadt@fonz.dk> wrote:

tirsdag den 6. august 2019 kl. 17.06.48 UTC+2 skrev Don Kuenz:
Tim Williams <tiwill@seventransistorlabs.com> wrote:
"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...

My recent audio mix-amp project motivated me to read, or at least skim,
dozens of articles about /audio/ ground loops. Either Bill Whitlock or
one of the other gurus said something along the lines of ground is a
equal potential myth used by engineers to make their jobs easier.
The exact wording and source of that aphorism are temporarily lost
to me. It's Whitlock who definitely dispels other myths about trying to
use thicker grounds or multiple grounds to fight loops.


when I took and emi class at uni one of the first thing the guy said was
something along the line of "ground does not exist"

It is usually in the form "universal ground _potential_ doesn't
exist", all ground potentials are different. Absolute ground potential
doesn't exist even in Sevre outside Paris, where they used to keep the
standard kilogram prototype and the standard meter prototype .

While there has been a lot of discussion in this thread about
grounding topologies inside the box, things get nasty when boxes are
connected together with perhaps a large distances between boxes.

A good practice is to have three separate grounding networks on site,
one for mains neutral N, one for the PE network and a separate
Technical/functional earth TE/FE networks. Each of these networks have
dedicated bars at the mains entry point of the building or complex. At
exactly this single point only the three bars are joined together with
jumpers as thick as your thumb. When the system is down, the jumpers
can be removed and measurements can be made to check that the networks
are truly separate.

The N network is polluted by mains return current of a single phase
system or the current imbalance in a three phase system. Even in a
balanced three phase system the third harmonics due to rectifier load
will pollute the neutral.

Mains power supply filters are usually connected to the PE, so it is
polluted by power supply noise.

Signal grounds are usually connected to the hopefully clean TE/FE
network. This requires that no equipments which has a signal ground
connected to the chassis and then to the PE are connected to TE/FE,
since a single mains filters will pollute the whole TE/FE network.

For this reason N, PE and signal grounds (TE/FE) should ne kept
separated and all three brought to the connection pins of a box, so
that they can be connected to three separate ground networks.

I have noticed a problem with some installers in foreign countries
that when they notice these three ground terminals they simply connect
jumpers between these terminals outside the box and use a single wire
for a connecting to mains neutral, now actually PEN :-(


That fancy approach works great until you find yourself working next to
a big VF motor drive.

What is a big VFD ? I have only experience with a few dozen VFDs, each
in the 10-100 kW range. Control signals with 20 mA current loops.

Try doing ultrasensitive measurements near one, and you'll see.

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 8/7/19 1:47 AM, Jan Panteltje wrote:

On a sunny day (Tue, 6 Aug 2019 18:24:32 -0400) it happened Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote in
qicun2$rn7$2@dont-email.me>:

On 8/6/19 2:43 PM, Tim Williams wrote:
"Jan Panteltje" <pNaOnStPeAlMtje@yahoo.com> wrote in message
news:qicbcm$ckr$1@dont-email.me...
I just wished people would no longer use filenames like
ThisSchematicIsTheLatestAndGreatest.PDF
3x.20_Precision-1.5kV-1us-Ramp_WH.pdf


My favorite is the,

Customer Project 12345_dingleBerryPOWERSUPPLY_REV_E.SCH

A true blend of DOS-style ALLCAPS (but still using LFNs?),
caps-avoidance, underscores (when a space apparently isn't available?)
AND spaces (oh..).

Working with other people has only reinforced my understanding that the
90-10 rule applies no matter how "educated" a group you're sampling...

Tim


I use camel case e.g. because it helps a lot finding the right file from
my archives, e.g.

2019-08-05-InvoiceABC05.pdf
TLV431AshuntRefOnSemiUnstableHorribleAvoidAvoid.pdf


~ # locate 3055 | grep -i pdf
/root/download/html/2N3055-D.pdf


Great filesystem organization you have there, Jan.

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

 

[Jan Panteltje]

On a sunny day (Wed, 7 Aug 2019 09:42:44 -0400) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<qiekgl$imh$1@dont-email.me>:

On 8/7/19 1:47 AM, Jan Panteltje wrote:
On a sunny day (Tue, 6 Aug 2019 18:24:32 -0400) it happened Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote in
qicun2$rn7$2@dont-email.me>:

On 8/6/19 2:43 PM, Tim Williams wrote:
"Jan Panteltje" <pNaOnStPeAlMtje@yahoo.com> wrote in message
news:qicbcm$ckr$1@dont-email.me...
I just wished people would no longer use filenames like
ThisSchematicIsTheLatestAndGreatest.PDF
3x.20_Precision-1.5kV-1us-Ramp_WH.pdf


My favorite is the,

Customer Project 12345_dingleBerryPOWERSUPPLY_REV_E.SCH

A true blend of DOS-style ALLCAPS (but still using LFNs?),
caps-avoidance, underscores (when a space apparently isn't available?)
AND spaces (oh..).

Working with other people has only reinforced my understanding that the
90-10 rule applies no matter how "educated" a group you're sampling...

Tim


I use camel case e.g. because it helps a lot finding the right file from
my archives, e.g.

2019-08-05-InvoiceABC05.pdf
TLV431AshuntRefOnSemiUnstableHorribleAvoidAvoid.pdf


~ # locate 3055 | grep -i pdf
/root/download/html/2N3055-D.pdf


Great filesystem organization you have there, Jan.

Cheers

Phil Hobbs

Thank you

Just run 'updatedb' every now and then, can even be done from crontab.

You could script it so it also scans other PCs on the LAN.

 

[John Larkin]

On Tue, 6 Aug 2019 18:21:57 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

That fancy approach works great until you find yourself working next to
a big VF motor drive.

It was impossible to do engineering in the same building with this one

https://www.dropbox.com/s/glsnthfa6bnluil/VFD.JPG?raw=1

until we hacked it in and out, which took a few iterations.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[John Larkin]

On Wed, 7 Aug 2019 06:36:27 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Tuesday, August 6, 2019 at 10:38:31 PM UTC-4, Phil Hobbs wrote:
On 8/6/19 10:02 AM, George Herold wrote:
On Monday, August 5, 2019 at 9:58:20 PM UTC-4, 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:
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.

Well I've got a pair of these,
https://www.amazon.com/Greenlee-PA1118-GripP-Stripper-Cutter/dp/B0006BHHDQ
(I guess Grennlee bought Paladin tools) If you don't have something like that
then that's what's coming for your B-day. I see Amazon has a deal on two pairs,
(different wire sizes.) I don't think I can make 'em jump out of a cake. :^)

George h.

Very kind of you, but I'd never use them. (The ones that come out of
the cake though...nah, I'd never use those either.)

OK, just trying to help you find the right tool.
After a while pounding nails with the crescent* hammer gets old.

George h.

It's impressive how often that the tool that you need is within reach,
if you're not too fussy.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Lasse Langwadt Christense]

onsdag den 7. august 2019 kl. 10.37.43 UTC+2 skrev upsid...@downunder.com:

On Wed, 7 Aug 2019 01:22:30 -0500, "Tim Williams"
tiwill@seventransistorlabs.com> wrote:

upsidedown@downunder.com> wrote in message
newsjnkke5qbdius6qf4f8a6af8i62e7koag2@4ax.com...
But then you get induced [electric] currents corrupting your signal.

With standard 20 mA current loop driven from a 24 Vdc supply will
carry nearly 0.5 W signal power, thus a quite strong interference is
needed to disturb the signal.

Unless it's quite precise. Recently had a customer ask for 24-bit inputs.
Ended up with a precision burden resistor, channel mux, in-amp and a TI SPI
ADC.

That 24 bit is quite special requirement, since it is more than 7
decimal digits. That might be needed when measuring the weight of a
car and then something 1 gram on the same scale. In such cases the
sampling period can be quite long, such as 100 ms, which cancels some
of 50 Hz as well as 60 Hz interference.

Some high quality audio use 24 bit ADCs, but the real accuracy is
about 20 bits (120 dB SNR).

Going digital at the signal source helps a lot.


Noise floor looks close to what the datasheet claims, so that's good news
about my front end. CMRR isn't bad, is visible but of a similar magnitude
(~100 counts over the input range). And hey, resistor matching, what do you
expect. (I added functionality so they can measure VCM and calibrate it out
in software if they want. And yes, customer's handing software.)

Since the inputs are filtered and essentially unloaded (only the filter
caps, mux switch, and in-amp input leakages), the inputs float very nicely,
and can be biased (in the common mode) by a touch of the finger. There is
some sequential charge transfer between channels, due the mux.

They couldn't give me a hard commitment on what ground reference or
polarity* the 4-20mA channels might be, so I had to do this (your
traditional +/-15V AFE). It's a 24V system and they really would've rather
had a 30V range, but that gets harder and harder to pull off (not so hard
regarding precision amps, but analog switches?).

*In the sense that there are high-side and low-side drivers. In an ideal
world, these are on isolated circuits so it doesn't matter, but, you know.
But it's a current loop, right? We don't care about voltage, the current
cures all!...Right? (See what really happens here?)


Using twisted pairs .e.g. telephone cables also limits the induced
interference.

Yup, pretty nice. Unless there's a nick in the insulation and now you have
current leakage from one or the other line...


Current loops have been done with optoisolators for nearly half a
century, so you also get galvanic isolation for 'free'. Powering the
loop always from the transmitter side, the receiver can be passive
(an IR LED) so no ground potential issues between boxes.

Optos are terrible! Unstable gain, poor distortion, slow speed. Fine for
serial. Basically useless above say 8 ENOB, and a few megbits.

Using dual optos at the transmitting side helps, if the other opto is
used for feedback.

the ones I have used are terrible and require calibration, the difference
between recievers are spec'ed to be something like +/- 10%

 

[Lasse Langwadt Christense]

onsdag den 7. august 2019 kl. 15.36.32 UTC+2 skrev George Herold:

On Tuesday, August 6, 2019 at 10:38:31 PM UTC-4, Phil Hobbs wrote:
On 8/6/19 10:02 AM, George Herold wrote:
On Monday, August 5, 2019 at 9:58:20 PM UTC-4, 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:
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.

Well I've got a pair of these,
https://www.amazon.com/Greenlee-PA1118-GripP-Stripper-Cutter/dp/B0006BHHDQ
(I guess Grennlee bought Paladin tools) If you don't have something like that
then that's what's coming for your B-day. I see Amazon has a deal on two pairs,
(different wire sizes.) I don't think I can make 'em jump out of a cake. :^)

George h.

Very kind of you, but I'd never use them. (The ones that come out of
the cake though...nah, I'd never use those either.)

OK, just trying to help you find the right tool.
After a while pounding nails with the crescent* hammer gets old.

George h.
*Gessh googling there are a bunch of crescent wrenches with built in hammers...
who knew.

aka. thumb detecting nut fucker or more general Swedish nut lathe

 

On Wed, 07 Aug 2019 08:24:32 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

On Tue, 6 Aug 2019 18:21:57 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

That fancy approach works great until you find yourself working next to
a big VF motor drive.


It was impossible to do engineering in the same building with this one

https://www.dropbox.com/s/glsnthfa6bnluil/VFD.JPG?raw=1

until we hacked it in and out, which took a few iterations.

Let me guess, it is a VFD for an air conditioning fan which spews
interference all over the HF bad, especially if installed against
instructions. No point of having an HF antenna on the same roof.

 

[Phil Hobbs]

On 8/7/19 9:36 AM, George Herold wrote:

On Tuesday, August 6, 2019 at 10:38:31 PM UTC-4, Phil Hobbs wrote:
On 8/6/19 10:02 AM, George Herold wrote:
On Monday, August 5, 2019 at 9:58:20 PM UTC-4, 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:
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.

Well I've got a pair of these,
https://www.amazon.com/Greenlee-PA1118-GripP-Stripper-Cutter/dp/B0006BHHDQ
(I guess Grennlee bought Paladin tools) If you don't have something like that
then that's what's coming for your B-day. I see Amazon has a deal on two pairs,
(different wire sizes.) I don't think I can make 'em jump out of a cake. :^)

George h.

Very kind of you, but I'd never use them. (The ones that come out of
the cake though...nah, I'd never use those either.)

OK, just trying to help you find the right tool.
After a while pounding nails with the crescent* hammer gets old.

George h.
*Gessh googling there are a bunch of crescent wrenches with built in hammers...
who knew.

Big clunky strippers and crimp tools are great for making cables. I'm
usually building protos, so I really need something small so I can
solder one end of the wire, gauge the length, cut, strip, and solder the
other end without changing tools, which slows me down. Hence the
Xcelite Model 170D flush cutters.

It's super easy with irradiated PVC, harder with Kynar, and impossible
with Teflon.

Cheers

Phil

(All of whose wrenches can also be hammers.)

--
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

 

On Tuesday, 6 August 2019 08:30:11 UTC+2, John Robertson wrote:

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.

There is no insulation in any of those connection methods.

 

On Tuesday, 6 August 2019 04:05:07 UTC+2, Phil Hobbs wrote:

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?

For cheap connections, and available robotics to handle the process, yes

Something that needs to be able to be disassembled, of course no

 

On Tuesday, 6 August 2019 03:49:45 UTC+2, Tim Williams wrote:

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?

It's a cold weld joint. No fretting possible, and you are right, it is a plated hole

 

[John Larkin]

On Wed, 07 Aug 2019 19:39:56 +0300, upsidedown@downunder.com wrote:

On Wed, 07 Aug 2019 08:24:32 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:

On Tue, 6 Aug 2019 18:21:57 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

That fancy approach works great until you find yourself working next to
a big VF motor drive.


It was impossible to do engineering in the same building with this one

https://www.dropbox.com/s/glsnthfa6bnluil/VFD.JPG?raw=1

until we hacked it in and out, which took a few iterations.

Let me guess, it is a VFD for an air conditioning fan which spews
interference all over the HF bad, especially if installed against
instructions. No point of having an HF antenna on the same roof.

It controlled an exhaust fan on the roof, for the reflow oven room a
floor down. We could see 20 volt spikes on oscilloscopes in our lab,
which happened to be right below the monster.

It was installed by licensed union electricians and all the wiring was
in conduit.

 

[Phil Hobbs]

On 8/7/19 2:09 PM, klaus.kragelund@gmail.com wrote:

On Tuesday, 6 August 2019 03:49:45 UTC+2, Tim Williams wrote:
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?


It's a cold weld joint. No fretting possible, and you are right, it
is a plated hole

IIRC some years ago there was a big fad about how you mustn't mate tin
and gold connectors. How did that come out, anyway?

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 Wed, 7 Aug 2019 17:43:13 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 8/7/19 2:09 PM, klaus.kragelund@gmail.com wrote:
On Tuesday, 6 August 2019 03:49:45 UTC+2, Tim Williams wrote:
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?


It's a cold weld joint. No fretting possible, and you are right, it
is a plated hole


IIRC some years ago there was a big fad about how you mustn't mate tin
and gold connectors. How did that come out, anyway?

The kids look weird.

 

On Wednesday, 7 August 2019 23:43:18 UTC+2, Phil Hobbs wrote:

On 8/7/19 2:09 PM, klaus.kragelund@gmail.com wrote:
On Tuesday, 6 August 2019 03:49:45 UTC+2, Tim Williams wrote:
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?


It's a cold weld joint. No fretting possible, and you are right, it
is a plated hole


IIRC some years ago there was a big fad about how you mustn't mate tin
and gold connectors. How did that come out, anyway?

AFAIR above 10um is wasted

 

On Wednesday, 7 August 2019 03:20:37 UTC+2, Phil Hobbs wrote:

On 8/6/19 9:08 PM, Sjouke Burry wrote:
On 07.08.19 0:24, Phil Hobbs wrote:
On 8/6/19 2:43 PM, Tim Williams wrote:
"Jan Panteltje" <pNaOnStPeAlMtje@yahoo.com> wrote in message
news:qicbcm$ckr$1@dont-email.me...
I just wished people would no longer use filenames like
ThisSchematicIsTheLatestAndGreatest.PDF
3x.20_Precision-1.5kV-1us-Ramp_WH.pdf


My favorite is the,

Customer Project 12345_dingleBerryPOWERSUPPLY_REV_E.SCH

A true blend of DOS-style ALLCAPS (but still using LFNs?),
caps-avoidance, underscores (when a space apparently isn't available?)
AND spaces (oh..).

Working with other people has only reinforced my understanding that the
90-10 rule applies no matter how "educated" a group you're sampling....

Tim


I use camel case e.g. because it helps a lot finding the right file from
my archives, e.g.

2019-08-05-InvoiceABC05.pdf
TLV431AshuntRefOnSemiUnstableHorribleAvoidAvoid.pdf

Cheers

Phil Hobbs

Camel case programmers should be removed from this earth.......

You probably use tabs instead of spaces too. Blech.

Funny clip about that:

https://m.youtube.com/watch?v=V7PLxL8jIl8&feature=youtu.be

Wind forward to 2:26 😊