USB device crashes Pi4/RasPiOS

[bob prohaska]

From time to time my Pi 4 running

Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux

crashes when a USB device is plugged into it.
The Pi4 boots from a usb3 mechanical disk.

Usually the culprit
is a storage device, but an FT232-based usb-serial adapter did it
also. The first symptom is an unresponsive menu bar and report about
I/O error on the command line. The palsy grows over a few minutes
as the mouse stops tracking. By that time there's nothing to do
but cycle power.

Plugged into a Windows 10 box the usb-serial adapter is recognized
just fine. I haven't been able to find a terminal emulator for Win
10 to test it further, but I suspect it's ok.

This behavior is relatively new, sometime in the last six months
or so. I don't remember it in the distant past. If I plug in a
camera it's recognized without difficulty.

Anybody else seen this sort of behavior or have a hint what to do?

Thanks for reading,

bob prohaska

[Chris Schram]

On 2024-01-07, bob prohaska <b...@www.zefox.net> wrote:
> From time to time my Pi 4 running
>
> Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
> Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
>
> crashes when a USB device is plugged into it.
> The Pi4 boots from a usb3 mechanical disk.

What I am about to describe may be an unrelated phenomenon:

I run a Pi4b in the Official Case with the Official Fan. [I don't
recommend that fan to anyone. It does not get much airflow unless the
case is propped open.]

The operation of the fan tends to build up a static charge throughout
the case's environment. When a USB device is plugged in, there is often
a brief static discharge, which can have an undesirable effect on the
Pi. I might get a screen glitch or a hang or a crash or a reboot,

I alleviate this problem by using an old unpowered Radio Shack USB hub.
This minimizes static buildup, and keeps any potential discharge some
distance from the Pi's circuit board.

--
ATTN Google Groups users: I filter out your posts and will not see them.
chri...@me.com is an infrequently monitored address. Email may get lost.

[Theo]

bob prohaska <b...@www.zefox.net> wrote:
> From time to time my Pi 4 running
>
> Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
> Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
>
> crashes when a USB device is plugged into it.
> The Pi4 boots from a usb3 mechanical disk.
>
> Usually the culprit
> is a storage device, but an FT232-based usb-serial adapter did it
> also. The first symptom is an unresponsive menu bar and report about
> I/O error on the command line. The palsy grows over a few minutes
> as the mouse stops tracking. By that time there's nothing to do
> but cycle power.

What does:

sudo dmesg

say immediately after you plug it in? You can print the last 30 lines with:

sudo dmesg | tail -30

It seems like the USB serial adapter wedges the USB subsystem, which is
problematic given your root filesystem is also on USB storage. The storage
stops responding, and over time programs get increasingly unhappy that their
storage is not functioning.

Another thing to try is to plug the serial adapter into a USB2 port, which
is a different controller on the Pi4 from the USB storage. Maybe that won't
break the storage?

Theo

[Michael Schwingen]

On 2024-01-07, bob prohaska <b...@www.zefox.net> wrote:

> From time to time my Pi 4 running
>
> Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
> Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
>
> crashes when a USB device is plugged into it.
> The Pi4 boots from a usb3 mechanical disk.

So either all USB is blocked, or the USB disk with the root FS stops
responding.

This might be a power issue. Mechanical disks pull a lot of power, and
unless it is a 1.8" drive this is often more than the 500mA allowed on
USB2.0 ports.

Make sure the power supply for the Pi can handle the (peak) load without
voltage drops. Aging power supplies and cables/connectors with bad contact
can cause slowly increasing problems.

You might try putting a self-powered USB hub (with its own power supply)
between the Pi and the disk and see if that changes anything.

cu
Michael
--
Some people have no respect of age unless it is bottled.

[bob prohaska]

Chris Schram <chri...@me.com> wrote:
> On 2024-01-07, bob prohaska <b...@www.zefox.net> wrote:
>> From time to time my Pi 4 running
>>
>> Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
>> Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
>>
>> crashes when a USB device is plugged into it.
>> The Pi4 boots from a usb3 mechanical disk.
>

> The operation of the fan tends to build up a static charge throughout
> the case's environment. When a USB device is plugged in, there is often
> a brief static discharge, which can have an undesirable effect on the
> Pi. I might get a screen glitch or a hang or a crash or a reboot,
>

Maybe. My Pi4 lives in a CanaKit (or similar) case with a little
5v fan running on 3.3 volts. There's certainly not enough zap to
make a noise, I've not been watching the display at the moment
of plug-in.

> I alleviate this problem by using an old unpowered Radio Shack USB hub.
> This minimizes static buildup, and keeps any potential discharge some
> distance from the Pi's circuit board.
>

It also lets the usb subsystem recognize the hub as a separate
object, apart from the thing you actually want to connect. I.E.,
it enumerates the hub, then enumerates the device. not both at once.
Dunno if that matters, but I'd think not.

You've raised an interesting point. I've noticed that if I put a
microSD card in a USB adapter and plug it into the pi, the pi
crashes. If I plug the adapter into the Pi and then plug the
card into the adapter, it works fine. Hubs are not the same as
adapters, but there's a whiff of similarity.

Thanks for writing!

bob prohaska

[bob prohaska]

Theo <theom...@chiark.greenend.org.uk> wrote:
> What does:
>
> sudo dmesg
>
> say immediately after you plug it in? You can print the last 30 lines with:
>
> sudo dmesg | tail -30
>

It says "I/O error", or words to that effect, in any
shell prompt. Enter produces a CR/LF combo and repeats
the prompt, but any typing provokes the I/O error message.

> It seems like the USB serial adapter wedges the USB subsystem, which is
> problematic given your root filesystem is also on USB storage. The storage
> stops responding, and over time programs get increasingly unhappy that their
> storage is not functioning.
>

Yes, that's my thinking too.

> Another thing to try is to plug the serial adapter into a USB2 port, which
> is a different controller on the Pi4 from the USB storage. Maybe that won't
> break the storage?
>

That's what I did, sorry if it wasn't clear. There is a keyboard on
USB2, so there's still potential for interaction and maybe the
"I/O error" is in reference to the keyboard input. Likewise,
the mouse hangs off a hub in the keyboard, so clicking on an
icon produces a similar effect..

You've brought up something that never crossed my mind. I've been
thinking "disk i/o", maybe it's "keyboard i/o" being reported.

Either way, it seems like a bug, except that few see it.
Strange.

Thanks for writing

[Computer Nerd Kev]

bob prohaska <b...@www.zefox.net> wrote:
> crashes when a USB device is plugged into it.
> The Pi4 boots from a usb3 mechanical disk.
>
> Usually the culprit
> is a storage device, but an FT232-based usb-serial adapter did it
> also. The first symptom is an unresponsive menu bar and report about
> I/O error on the command line. The palsy grows over a few minutes
> as the mouse stops tracking. By that time there's nothing to do
> but cycle power.

[snip]

> This behavior is relatively new, sometime in the last six months
> or so. I don't remember it in the distant past. If I plug in a
> camera it's recognized without difficulty.
>
> Anybody else seen this sort of behavior or have a hint what to do?

I've found that my RPi Zeros tend to reboot when a USB device is
plugged in. I presume it's a power issue to do with the wimpy 600mA
USB plugpacks that I power them from, but as I mainly just have a
wireless keyboard/mouse receiver pluged in all the time it doesn't
worry me much. It could also be that the tracks on the PCB are too
narrow and dropping too much voltage due to resistance during the
surge when a device is connected, in which case you might want a
PSU that outputs nearer to the maximum safe input voltage for the
Pi (5.25V? 5.5V? I'm not sure if they've specified this).

The camera likely is powered by its own battery and only uses USB
for I/O, so with that working every time it definately suggests a
power issue.

--
__ __
#_ < |\| |< _# | Note: I won't see posts made from Google Groups |

[57r.1283]

On 1/7/24 8:51 PM, Chris Schram wrote:
> On 2024-01-07, bob prohaska <b...@www.zefox.net> wrote:
>> From time to time my Pi 4 running
>>
>> Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT
>> Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
>>
>> crashes when a USB device is plugged into it.
>> The Pi4 boots from a usb3 mechanical disk.
>
> What I am about to describe may be an unrelated phenomenon:
>
> I run a Pi4b in the Official Case with the Official Fan. [I don't
> recommend that fan to anyone. It does not get much airflow unless the
> case is propped open.]
>
> The operation of the fan tends to build up a static charge throughout
> the case's environment. When a USB device is plugged in, there is often
> a brief static discharge, which can have an undesirable effect on the
> Pi. I might get a screen glitch or a hang or a crash or a reboot,
>
> I alleviate this problem by using an old unpowered Radio Shack USB hub.
> This minimizes static buildup, and keeps any potential discharge some
> distance from the Pi's circuit board.

Buy a pack of bubble-gum ... the foil/paper wrapper for
each stick can be teased into its component parts. The
ultra-thin foil is slightly sticky. Stick it all over the
inside of the case (we used to stick 'em to school desks
back in the day) by rubbing it on with a bit of hard wood
or something of similar characteristics. A pencil worked
for the school desks.

Weave in a fine wire that touches both the ground plane
of the Pi and the foil in the case. Doesn't have to be a
super-good soldered connection.

If you use WiFi then maybe leave the upper 1/3rd of the
case un-foiled around where the WiFi antenna thingie is.
An all-metal case would work for the static, but will
block a lot of the WiFi signal.

This should safely drain-off static charge.

Apparently you live in a VERY dry area - always a prob
for electronics. Hell, lived in a US western town high
in the mountains for awhile. In the winter you could
easily draw a 4-inch spark off a door-knob just by
walking across a carpet first. Guess that's about a
200,000 volts or so. Actually HURT ! You learned to
lead with a knuckle ....

Oh yea, Pi-compatible fans ... they mostly ARE crap.
Lucky if you can go 6-months before the bearing goes
and they start making noise. OTOH, they only cost a
couple of dollars ........

[Ahem A Rivet's Shot]

On Mon, 8 Jan 2024 23:03:28 -0500
"57r.1283" <57r....@etq5.net> wrote:

> Buy a pack of bubble-gum ... the foil/paper wrapper for
> each stick can be teased into its component parts. The
> ultra-thin foil is slightly sticky.

Alternatively buy a roll of copper or aluminium tape, both are
easily available.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/
Host: Beautiful Theory meet Inconvenient Fact
Obit: Beautiful Theory died today of factual inconsistency

[The Natural Philosopher]

On 09/01/2024 04:03, 57r.1283 wrote:
> Buy a pack of bubble-gum ... the foil/paper wrapper for
>   each stick can be teased into its component parts. The
>   ultra-thin foil is slightly sticky. Stick it all over the
>   inside of the case (we used to stick 'em to school desks
>   back in the day) by rubbing it on with a bit of hard wood
>   or something of similar characteristics. A pencil worked
>   for the school desks.
>
>   Weave in a fine wire that touches both the ground plane
>   of the Pi and the foil in the case. Doesn't have to be a
>   super-good soldered connection.
>
>   If you use WiFi then maybe leave the upper 1/3rd of the
>   case un-foiled around where the WiFi antenna thingie is.
>   An all-metal case would work for the static, but will
>   block a lot of the WiFi signal.
>
>   This should safely drain-off static charge.

You can buy adhesive backed copper foil, made for sheilding electric
guitars and similar quite cheaply - and its a cinch to solder to it to
earth it


--
“A leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
“We did this ourselves.”

― Lao Tzu, Tao Te Ching

[Joerg Walther]

57r.1283 wrote:

>Oh yea, Pi-compatible fans ... they mostly ARE crap.

That's why I only use solid body aluminium cases with my Pi3s and Pi4s,
no fan needed. Don't know if this is still possible with the Pi5,
though.

-jw-

--

And now for something completely different...

[Charlie Gibbs]

On 2024-01-09, 57r.1283 <57r....@etq5.net> wrote:

> Apparently you live in a VERY dry area - always a prob
> for electronics. Hell, lived in a US western town high
> in the mountains for awhile. In the winter you could
> easily draw a 4-inch spark off a door-knob just by
> walking across a carpet first. Guess that's about a
> 200,000 volts or so. Actually HURT ! You learned to
> lead with a knuckle ....

I would tightly grip a key and draw the spark off it.

--
/~\ Charlie Gibbs | The Internet is like a big city:
\ / <cgi...@kltpzyxm.invalid> | it has plenty of bright lights and
X I'm really at ac.dekanfrus | excitement, but also dark alleys
/ \ if you read it the right way. | down which the unwary get mugged.

[Robert Riches]

On 2024-01-09, Charlie Gibbs <cgi...@kltpzyxm.invalid> wrote:
> On 2024-01-09, 57r.1283 <57r....@etq5.net> wrote:
>
>> Apparently you live in a VERY dry area - always a prob
>> for electronics. Hell, lived in a US western town high
>> in the mountains for awhile. In the winter you could
>> easily draw a 4-inch spark off a door-knob just by
>> walking across a carpet first. Guess that's about a
>> 200,000 volts or so. Actually HURT ! You learned to
>> lead with a knuckle ....
>
> I would tightly grip a key and draw the spark off it.

Or, if you can find an old pen body with a metal upper half and a
plastic lower half, put a NE2 neon light bulb poking out of the
top end. Connect one side of the bulb to the metal upper body
half. Through a current-limiting series resistor, connect the
other end to a metal protrusion from the tip of the pen. If I
remember correctly, under the right conditions the charge will
run the bulb for a couple of seconds. (It was ~50 years ago when
I did that.)

In a pinch, a ring or metal watchband can also do the job.

HTH

--
Robert Riches
spamt...@jacob21819.net
(Yes, that is one of my email addresses.)

[57r.1283]

On 1/9/24 2:07 AM, Ahem A Rivet's Shot wrote:
> On Mon, 8 Jan 2024 23:03:28 -0500
> "57r.1283" <57r....@etq5.net> wrote:
>
>> Buy a pack of bubble-gum ... the foil/paper wrapper for
>> each stick can be teased into its component parts. The
>> ultra-thin foil is slightly sticky.
>
> Alternatively buy a roll of copper or aluminium tape, both are
> easily available.

Aluminum and/or stainless-steel tape is often sold at
automotive parts stores. Not gonna say what the nickname
for it may be. Copper tape ... never seen it in the USA
in retail stores (can be had from electronics suppliers
like Mouser or Digi-Key).

Either would be fairly effective for the OPs problem,
but the bubble-gum solution is More Fun ! :-)

There is also conductive PAINT ...

https://3dinsider.com/conductive-paint/

... which should also drain-off pesky static.

In any case, the OP seems to live in an EXTREMELY
dry environment. Surprised he doesn't lose devices
all the time.

[57r.1283]

On 1/9/24 4:07 AM, The Natural Philosopher wrote:
> On 09/01/2024 04:03, 57r.1283 wrote:
>> Buy a pack of bubble-gum ... the foil/paper wrapper for
>>    each stick can be teased into its component parts. The
>>    ultra-thin foil is slightly sticky. Stick it all over the
>>    inside of the case (we used to stick 'em to school desks
>>    back in the day) by rubbing it on with a bit of hard wood
>>    or something of similar characteristics. A pencil worked
>>    for the school desks.
>>
>>    Weave in a fine wire that touches both the ground plane
>>    of the Pi and the foil in the case. Doesn't have to be a
>>    super-good soldered connection.
>>
>>    If you use WiFi then maybe leave the upper 1/3rd of the
>>    case un-foiled around where the WiFi antenna thingie is.
>>    An all-metal case would work for the static, but will
>>    block a lot of the WiFi signal.
>>
>>    This should safely drain-off static charge.
>
> You can buy adhesive backed copper foil, made for sheilding electric
> guitars and similar quite cheaply - and its a cinch to solder to it to
> earth it

Yep ... but WHERE ? Never seen it on a shelf in the USA.
Is it more common in the UK perhaps ? For what use ?

However aluminum/SS tape is more readily found in retail
locations. Problem is that you can't solder to it. However
even a "spring" connection will serve. Conductive paint
can be had too, but only from electronics suppliers.

[Ahem A Rivet's Shot]

On Wed, 10 Jan 2024 01:29:18 -0500
"57r.1283" <57r....@etq5.net> wrote:

> On 1/9/24 2:07 AM, Ahem A Rivet's Shot wrote:
> > On Mon, 8 Jan 2024 23:03:28 -0500

> > Alternatively buy a roll of copper or aluminium tape, both are
> > easily available.
>
>
> Aluminum and/or stainless-steel tape is often sold at

Aluminium tape is sold in builder's merchants for taping insulation
boards for air tightness (I used several rolls of it insulating my house),
it also sometimes gets used to seal air duct joins.

> automotive parts stores. Not gonna say what the nickname
> for it may be. Copper tape ... never seen it in the USA
> in retail stores (can be had from electronics suppliers
> like Mouser or Digi-Key).

It can sometimes be found in garden centres as gardeners use it for
slug/snail repellent, it is also used for making stained glass and
repairing electrical toys like Scalextric track. Copper tape comes in a very
wide variety of widths unlike aluminium tape, I have 6mm, 10mm and 50mm
rolls to hand.

[Ahem A Rivet's Shot]

On Wed, 10 Jan 2024 01:34:17 -0500
"57r.1283" <57r....@etq5.net> wrote:

> Yep ... but WHERE ?

Amazon (easiest), a good electronics parts retailer (OK they're hens
teeth these days) or a good garden centre.

[Theo]

This is quite possible. Especially if the widget you plug in has a big
decoupling capacitor, it could take a current spike which causes the supply
voltage to drop out momentarily and could upset further communications.

One thing to try would be to put the widget behind a powered hub. Plug the
widget into the hub, make sure the hub power is on, then plug the hub into
the Pi. That way there will be no increased power loading on the Pi as the
widget is plugged in.

Theo

[Andy Burns]

57r.1283 wrote:

> The Natural Philosopher wrote:
>
>> You can buy adhesive backed copper foil, made for sheilding electric
>> guitars and similar quite cheaply - and its a cinch to solder to it to
>> earth it
>
>   Yep ... but WHERE ? Never seen it on a shelf in the USA.
>   Is it more common in the UK perhaps ?

Probably not on shelves here, nowadays for anything useful you tend to
have to buy online

> For what use ?
Slug repellent, stained glass work, EMI shielding, lining guitar cavity ...

[The Natural Philosopher]

On 10/01/2024 06:34, 57r.1283 wrote:
> On 1/9/24 4:07 AM, The Natural Philosopher wrote:
>> On 09/01/2024 04:03, 57r.1283 wrote:
>>> Buy a pack of bubble-gum ... the foil/paper wrapper for
>>>    each stick can be teased into its component parts. The
>>>    ultra-thin foil is slightly sticky. Stick it all over the
>>>    inside of the case (we used to stick 'em to school desks
>>>    back in the day) by rubbing it on with a bit of hard wood
>>>    or something of similar characteristics. A pencil worked
>>>    for the school desks.
>>>
>>>    Weave in a fine wire that touches both the ground plane
>>>    of the Pi and the foil in the case. Doesn't have to be a
>>>    super-good soldered connection.
>>>
>>>    If you use WiFi then maybe leave the upper 1/3rd of the
>>>    case un-foiled around where the WiFi antenna thingie is.
>>>    An all-metal case would work for the static, but will
>>>    block a lot of the WiFi signal.
>>>
>>>    This should safely drain-off static charge.
>>
>> You can buy adhesive backed copper foil, made for sheilding electric
>> guitars and similar quite cheaply - and its a cinch to solder to it to
>> earth it
>
>
>   Yep ... but WHERE ? Never seen it on a shelf in the USA.
>   Is it more common in the UK perhaps ? For what use ?
>

Shielding electric guitars. I got mine from amazon. Here in the UK we
don't have 'shelves' except in online suppliers warehouse, and food
supermarkets.

https://www.amazon.com/Quality-Conductive-Adhesive-Shielding-Flashing/dp/B0CGF45N88/

Aluminium foil sticky tape is used to vapour seal foil covered
insulation so a builders merchant will stock it

https://www.amazon.com/BOMEI-Aluminum-SilverTape-Insulation-Temperature/dp/B0C4Y2YSPB/


You *can* solder to aluminium,. You just need the right flux, And
breathing apparatus!

The one I used is UK specific. Made by Carrs. keep a window open though.


--
“Progress is precisely that which rules and regulations did not foresee,”

– Ludwig von Mises

[The Natural Philosopher]

On 10/01/2024 07:08, Ahem A Rivet's Shot wrote:
> On Wed, 10 Jan 2024 01:34:17 -0500
> "57r.1283" <57r....@etq5.net> wrote:
>
>> Yep ... but WHERE ?
>
> Amazon (easiest), a good electronics parts retailer (OK they're hens
> teeth these days) or a good garden centre.
>

Or a Lutiers supplier.

https://www.stewmac.com/electronics/shielding/conductive-copper-tape

--
“But what a weak barrier is truth when it stands in the way of an
hypothesis!”

Mary Wollstonecraft

[Björn Lundin]

On 2024-01-10 07:29, 57r.1283 wrote:
>
>   In any case, the OP seems to live in an EXTREMELY
>   dry environment. Surprised he doesn't lose devices
>   all the time.

A cold winter day makes much spark here. (Sweden)
Like -10C or below


Fabric softener helps, but below some temperatures, even that does not
do much to help.


--
/Björn

[57r.1283]

On 1/10/24 2:05 AM, Ahem A Rivet's Shot wrote:
> On Wed, 10 Jan 2024 01:29:18 -0500
> "57r.1283" <57r....@etq5.net> wrote:
>
>> On 1/9/24 2:07 AM, Ahem A Rivet's Shot wrote:
>>> On Mon, 8 Jan 2024 23:03:28 -0500
>
>>> Alternatively buy a roll of copper or aluminium tape, both are
>>> easily available.
>>
>>
>> Aluminum and/or stainless-steel tape is often sold at
>
> Aluminium tape is sold in builder's merchants for taping insulation
> boards for air tightness (I used several rolls of it insulating my house),
> it also sometimes gets used to seal air duct joins.
>
>> automotive parts stores. Not gonna say what the nickname
>> for it may be. Copper tape ... never seen it in the USA
>> in retail stores (can be had from electronics suppliers
>> like Mouser or Digi-Key).
>
> It can sometimes be found in garden centres as gardeners use it for
> slug/snail repellent, it is also used for making stained glass and
> repairing electrical toys like Scalextric track. Copper tape comes in a very
> wide variety of widths unlike aluminium tape, I have 6mm, 10mm and 50mm
> rolls to hand.

I have a roll of 10cm ... but got that from an electronics surplus
place in Orlando.

However that's the only place I've ever seen it on a shelf in
the USA.

[57r.1283]

I could get 4" (100mm) sparks off round door-knobs
during the winter in a high Rocky Mountain town.
Were strong enough to HURT. You quickly learned
to reach with a knuckle or key. My guess, given
the rounded surface, is 200,000 volts. That's
enough to trash modern electronics for sure
unless very well shielded and smartly designed.

Hmm ... I wonder how long cell phones last in
places like that ? :-)

[68g.1499]

Um, yea ... the flux CAN be nasty :-)

> The one I used is UK specific. Made by Carrs. keep a window open though.

For those in the USA, try Skycraft Salvage in Orlando Florida.

https://skycraftsurplus.com/

Whatever it is, they DO have it on a shelf somewhere :-)

SOME you can buy online. MOST is just in infinite bins
you have to pick through. I usually spend hundreds every
time I get by there. And yes, they DO have thin copper
tape, I bought a roll of 10mm awhile back.

Note recent physical address change to bigger digs from
their old Fairbanks Av location. New place is in a strip
mall about a mile N.W. from there.

[Bryan]

>>
>>
>> Aluminium foil sticky tape is used to vapour seal foil covered
>> insulation so a builders merchant will stock it
>>

You can sometime also find stainless steel tape in the form of
automotive trim and MacGuyver rust-out repair material. If all else
fails, automotive customizers can be a good place to get things that can
be adapted for other uses.

[68g.1499]

SS tape has one extra advantage, as it does not form a
thick surface oxidation layer like aluminum you can
employ 'friction contacts' more effectively, eliminating
the need for hard soldered connections. This should serve
for RF shielding.

BUT, you can get copper tape from Mouser or DigiKey or
Amazon - so ...

[Bryan]

Yes. I'd rather use copper. But when you need it right now because SHTF,
it's nice to have options.

[68g.1499]

Yea, I know ... when you need it you need it and don't
want to wait days/weeks.

But, for a number of reasons, 'retail' ain't what it
used to be. The more 'popular' items get shelf priority
and other stuff disappears ("You can buy it from our
online store !")

Someone suggested buying copper tape from my local
garden store - except the last one anywhere near me
went out of biz around Covid-time.

ANYway ... Amazon delivers pretty quick (quicker if
you want to $$$). McMaster/Carr is also very quick,
but may not do 'retail' in your area. Grainger is
quick, and does do retail, but adds a big premium
if you're not an official 'wholesaler' with the right
numbers to present.

Oh, do you have a "Northern Tools" store anywhere
near ? They've got a surprising volume of "weird
shit" on their shelves.

I've got enough copper tape for any anticipated need.
But what DON'T I have ? I'll find out come the next
project ... it's always something ... :-)