Arduino Relay Board...

[Sylvia Else]

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.

 

[Phil Allison]

Sylvia Else wrote:
===============

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

** So the relay is rated for 230/240V AC?

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

** That is not enough clearance for 240V.

Be fine for 12VDC or AC though.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

** Then don\'t.


........ Phil

 

[Sylvia Else]

On 03-Feb-22 5:28 pm, Phil Allison wrote:

Sylvia Else wrote:
===============

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

** So the relay is rated for 230/240V AC?

Yes.

Sylvia.

 

[Mike Coon]

In article <j618kbF9s19U1@mid.individual.net>, sylvia@email.invalid
says...

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.

I imagine you have something like Trading Standards with which you could
raise a CE accreditation query. However it is a bit niche and they may
reasonably give priority to verifying (e.g.) childs\' toys...

 

[Dan Purgert]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Sylvia Else wrote:

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

It\'s hard to tell since it\'s just a bottom shot, but given the
positioning, I\'d hazard that\'s the flyback diode for when the coil field
is collapsing.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

In the general sense, it it perfectly safe to use in arduino projects.

Whether or not it is \"safe\" for the project you had in mind for it is
another matter entirely.



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|_|O|_| Github: https://github.com/dpurgert
|_|_|O| PGP: DDAB 23FB 19FA 7D85 1CC1 E067 6D65 70E5 4CE7 2860
|O|O|O|

 

[TTman]

On 03/02/2022 05:47, Sylvia Else wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.
gap 240v to LVDC should be 5mm ?

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[Johann Klammer]

On 02/03/2022 06:47 AM, Sylvia Else wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs across the isolation barrier, near to the mains contacts. It runs to a diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe that this is actually safe.

Sylvia.

It\'s that self-certification thing, innit?
In Principle anyone can slap a CE sign on a board.
Consequences will only arise if somone complains.

 

[Tauno Voipio]

On 3.2.22 7.47, Sylvia Else wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.

Are you sure that the label is the EU conformity label and not the
very similar-looking China Export label.

In principle, the EU CE label is a declaration by the manufacturer
that the product conforms to the relevant safety requirements. It
is up to the conscience of the manufacturer how well this is done.

--

-TV

 

[Ralph Mowery]

In article <stgovt$vqe$1@dont-email.me>, tauno.voipio@notused.fi.invalid
says...

Are you sure that the label is the EU conformity label and not the
very similar-looking China Export label.

In principle, the EU CE label is a declaration by the manufacturer
that the product conforms to the relevant safety requirements. It
is up to the conscience of the manufacturer how well this is done.

You beat me to it.

I was going to say that the CE was probably the China Export instead of
the EU CE for safety.

 

[Lasse Langwadt Christensen]

torsdag den 3. februar 2022 kl. 16.33.20 UTC+1 skrev Ralph Mowery:

In article <stgovt$vqe$1...@dont-email.me>, tauno....@notused.fi.invalid
says...

Are you sure that the label is the EU conformity label and not the
very similar-looking China Export label.

In principle, the EU CE label is a declaration by the manufacturer
that the product conforms to the relevant safety requirements. It
is up to the conscience of the manufacturer how well this is done.



You beat me to it.

I was going to say that the CE was probably the China Export instead of
the EU CE for safety.

afaik the \"China Export\" is just an urban myth, in reality it was just someone
that didn\'t follow the spec for how the CE mark should look

 

[Lasse Langwadt Christensen]

torsdag den 3. februar 2022 kl. 12.11.15 UTC+1 skrev Dan Purgert:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Sylvia Else wrote:

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.
It\'s hard to tell since it\'s just a bottom shot, but given the
positioning, I\'d hazard that\'s the flyback diode for when the coil field
is collapsing.

yes, looks like this one: https://www.amazon.com/Tolako-Arduino-Indicator-Channel-Official/dp/B00VRUAHLE

who ever designed it obviously didn\'t spend much time thinking, because there is no reason for those tracks being routed that close to the output side

 

[Fred Bloggs]

On Thursday, February 3, 2022 at 12:48:02 AM UTC-5, Sylvia Else wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

If the ckt connected to the small race is truly isolated from mains gnd then the impedance is extremely high and any arc over cannot deliver any energy to speak of.

Sylvia.

 

[server]

Sylvia Else <sylvia@email.invalid> wrote in
news:j618kbF9s19U1@mid.individual.net:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=
0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the
right.

What bothers me is the trace from one of the control contacts that
runs across the isolation barrier, near to the mains contacts. It
runs to a diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to
believe that this is actually safe.

Sylvia.

It runs on DC, right? Not an AC device form the looks and size of
it.
So \"isolation\" is all about \"line isolation\" on the AC side of a
system.

That appears to be DC driven, but you would isolate at the AC side
of the DC supply, not at that PCB assy. Likely a dongle type,
plastic encapsulated fully isolated wall wart. Many do not even have
a transformer in them nowadays.

And a diode across the relay drive circuit will quell any back EMF.
For most relays. You could use an SSR. They make those pretty small
form factor these days too.

 

[Jasen Betts]

On 2022-02-03, Sylvia Else <sylvia@email.invalid> wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Do they make any voltage claims for this module?

As you say the diode trace goes close to the contact trace but they have
about 4mm clearance between the exposed conductore. They\'ve put solder
mask and silk screen on the traces, I guess they\'re trying to call
that silkscreen suplimental insulation, but it seems to stop short of
where it should be. Maybe they are just apeing someone elses design
which had better layout.

More worrying, the exposed relay common contact pin is close to
header pin 1, it looks like less than 2mm clearance there.

Some designers will route a groove around the common pin to give
better isolation between the coil and the contacts, but I much prefer
relays that have the coil terminals at one end and the contacts at the
other end.


--
Jasen.

 

[Sylvia Else]

On 05-Feb-22 9:24 am, Jasen Betts wrote:

On 2022-02-03, Sylvia Else <sylvia@email.invalid> wrote:
I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Do they make any voltage claims for this module?

As you say the diode trace goes close to the contact trace but they have
about 4mm clearance between the exposed conductore. They\'ve put solder
mask and silk screen on the traces, I guess they\'re trying to call
that silkscreen suplimental insulation, but it seems to stop short of
where it should be. Maybe they are just apeing someone elses design
which had better layout.

More worrying, the exposed relay common contact pin is close to
header pin 1, it looks like less than 2mm clearance there.

Some designers will route a groove around the common pin to give
better isolation between the coil and the contacts, but I much prefer
relays that have the coil terminals at one end and the contacts at the
other end.

This is the product page:

https://au.element14.com/mcm/83-17990/5v-trigger-relay-module-for-arduinoraspberry/dp/2801412

You may note that the picture doesn\'t match. The data sheet provided is
for the relay itself, rather than the module.

At the time of posting I hadn\'t realised where the common pin was. As
you\'ve observed, it represents another isolation concern.

Sylvia.

 

[Lasse Langwadt Christensen]

lørdag den 5. februar 2022 kl. 00.44.00 UTC+1 skrev Sylvia Else:

On 05-Feb-22 9:24 am, Jasen Betts wrote:
On 2022-02-03, Sylvia Else <syl...@email.invalid> wrote:
I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Do they make any voltage claims for this module?

As you say the diode trace goes close to the contact trace but they have
about 4mm clearance between the exposed conductore. They\'ve put solder
mask and silk screen on the traces, I guess they\'re trying to call
that silkscreen suplimental insulation, but it seems to stop short of
where it should be. Maybe they are just apeing someone elses design
which had better layout.

More worrying, the exposed relay common contact pin is close to
header pin 1, it looks like less than 2mm clearance there.

Some designers will route a groove around the common pin to give
better isolation between the coil and the contacts, but I much prefer
relays that have the coil terminals at one end and the contacts at the
other end.


This is the product page:

https://au.element14.com/mcm/83-17990/5v-trigger-relay-module-for-arduinoraspberry/dp/2801412

You may note that the picture doesn\'t match. The data sheet provided is
for the relay itself, rather than the module.

At the time of posting I hadn\'t realised where the common pin was. As
you\'ve observed, it represents another isolation concern.

the picture is a different module, the diode is smd and there\'s a cutout around the common pin

 

[Sylvia Else]

On 05-Feb-22 10:52 am, Lasse Langwadt Christensen wrote:

lørdag den 5. februar 2022 kl. 00.44.00 UTC+1 skrev Sylvia Else:
On 05-Feb-22 9:24 am, Jasen Betts wrote:
On 2022-02-03, Sylvia Else <syl...@email.invalid> wrote:
I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Do they make any voltage claims for this module?

As you say the diode trace goes close to the contact trace but they have
about 4mm clearance between the exposed conductore. They\'ve put solder
mask and silk screen on the traces, I guess they\'re trying to call
that silkscreen suplimental insulation, but it seems to stop short of
where it should be. Maybe they are just apeing someone elses design
which had better layout.

More worrying, the exposed relay common contact pin is close to
header pin 1, it looks like less than 2mm clearance there.

Some designers will route a groove around the common pin to give
better isolation between the coil and the contacts, but I much prefer
relays that have the coil terminals at one end and the contacts at the
other end.


This is the product page:

https://au.element14.com/mcm/83-17990/5v-trigger-relay-module-for-arduinoraspberry/dp/2801412

You may note that the picture doesn\'t match. The data sheet provided is
for the relay itself, rather than the module.

At the time of posting I hadn\'t realised where the common pin was. As
you\'ve observed, it represents another isolation concern.


the picture is a different module, the diode is smd and there\'s a cutout around the common pin

I hadn\'t noticed the cut-out, but yes, it\'s different. There\'s a pale
grey \"Image is for illustrative purposes only\" caveat underneath. A
downside of the illustrated module though is that it has no mounting
holes. Still, it makes the point that the job could have been done
properly by someone who knows what they\'re doing.

Sylvia.

 

[Sylvia Else]

On 03-Feb-22 4:47 pm, Sylvia Else wrote:

I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.

I decided to sacrifice the relay itself to examine its construction:

https://www.dropbox.com/s/ly8wlfnkvpl1ea9/c_relay.jpg?dl=0

If the coil wire were to break off its pin there, it could get horribly
close to the mains connected (brass?) plate.

I salvaged four of these from my dead UPS:

https://au.element14.com/omron/g2r-1-e-12dc/relay-spdt-250vac-30vdc-16a/dp/9949410?st=g2r-1

They\'ve clearly been designed so that there\'s no credible failure mode
that would connect the load to the coil.

Sylvia.

 

[server]

Sylvia Else <sylvia@email.invalid> wrote in
news:j6684cF8ml5U1@mid.individual.net:

On 03-Feb-22 4:47 pm, Sylvia Else wrote:
I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl
=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the
right.

What bothers me is the trace from one of the control contacts
that runs across the isolation barrier, near to the mains
contacts. It runs to a diode, from which another traces runs back
to the right.

The packaging carries a CE label, but I find it difficult to
believe that this is actually safe.

Sylvia.

I decided to sacrifice the relay itself to examine its
construction:

https://www.dropbox.com/s/ly8wlfnkvpl1ea9/c_relay.jpg?dl=0

That is a pretty sad assembly. Hand tweaked lead positions after
soldering too, I\'m sure.

If the coil wire were to break off its pin there, it could get
horribly close to the mains connected (brass?) plate.

I salvaged four of these from my dead UPS:

https://au.element14.com/omron/g2r-1-e-12dc/relay-spdt-250vac-30vdc
-16a/dp/9949410?st=g2r-1

They\'ve clearly been designed so that there\'s no credible failure
mode that would connect the load to the coil.

Those are nice industry pro grade parts.

 

[Cydrome Leader]

Sylvia Else <sylvia@email.invalid> wrote:

On 03-Feb-22 4:47 pm, Sylvia Else wrote:
I bought this Arduino Relay Board.

https://www.dropbox.com/s/emgdcm33190unse/ArduinoRelayBoard.jpg?dl=0

It\'s about 33mm by 20mm.

The mains contacts are on the left, the control contacts on the right.

What bothers me is the trace from one of the control contacts that runs
across the isolation barrier, near to the mains contacts. It runs to a
diode, from which another traces runs back to the right.

The packaging carries a CE label, but I find it difficult to believe
that this is actually safe.

Sylvia.

I decided to sacrifice the relay itself to examine its construction:

https://www.dropbox.com/s/ly8wlfnkvpl1ea9/c_relay.jpg?dl=0

If the coil wire were to break off its pin there, it could get horribly
close to the mains connected (brass?) plate.

And? The cheapest of relays are cheapy made. If you need safety look up
intrinsically safe relays, and no don\'t then try buy buy fakes ones from
amazon or alibaba.

I salvaged four of these from my dead UPS:

https://au.element14.com/omron/g2r-1-e-12dc/relay-spdt-250vac-30vdc-16a/dp/9949410?st=g2r-1

They\'ve clearly been designed so that there\'s no credible failure mode
that would connect the load to the coil.

Sylvia.

Let me guess, one Omron relay costs the same as 5 chinese house-special relay boards.