Arduino Forum

Using Arduino => General Electronics => Topic started by: falexandru on Apr 15, 2018, 01:18 pm

Title: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 01:18 pm
My cat loves to sit on my table while I am digging into electronic circuits. Obviously, my cat has fur.

Question is: can cat's fur affect the electronic circuits? Either still on the cat or falling out of the cat.

++++

Long ago, I cleaned up my printer's internal components by a brush. I ended up by enjoying a clean and dead printer.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: pert on Apr 15, 2018, 01:54 pm
It seems like cats could certainly be an effective source of ESD. Not sure how much of an issue that would be with loose hair but certainly petting the cat while handling sensitive components during dry times of the year with being grounded could be a seriously bad idea.

I'm sure any sort of contaminant on a circuit can affect it. That could be by promoting corrosion, conductance, capacitance. Even if the contaminants themselves don't have problematic properties, they can absorb moisture from the air, which does.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Southpark on Apr 15, 2018, 02:04 pm
My cat loves to sit on my table while I am digging into electronic circuits. Obviously, my cat has fur.

Question is: can cat's fur affect the electronic circuits? Either still on the cat or falling out of the cat
Maybe if you rub the cat's fur on some esd sensitive devices.... or touch esd sensitive devices after patting your cat...then maybe you can get esd damage. If it's not a critical thing.... then ok. Otherwise.... if avoiding esd damage is important.... then read up about esd issues. And use google to search for 'esd' ... and select 'images'. It will show lots of images of devices at microscopic levels....damaged by esd.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 02:09 pm
I once extensively searched for ESD issues. At that time my conclusion was that ESD is not of so much concern usually, on Arduino platform and keeping into account that one way or another the human touches something that grounds him or her.

+++

Now I see the cat's fur on my desk - perhaps on the circuits as well, I cant say.

The cat rubs himself (is a tomcat) to the surface of my desk and occasionally moves. Since obviousely the cat has more hair than I have, that may be a problem, not sure.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Southpark on Apr 15, 2018, 03:13 pm
I once extensively searched for ESD issues. At that time my conclusion was that ESD is not of so much concern usually, on Arduino platform and keeping into account that one way or another the human touches something that grounds him or her.
Yep....true. Your original posted mentioned 'electronics' .... not arduino specifically. Having knowledge about esd damage is handy. Whether or not we apply any techniques to avoid or minimise esd-related issues is just up to ourselves. It's a choice thing in many cases. In other cases.... there may be procedures that must be adhered to (grounding etc) .... in various professional electronic companies/labs.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 03:26 pm
Agree. And mea culpa for not specific reference to Arduino (hobby) environment.

Perhaps I will anyway ground the cat somehow. Or touch him time by time to discharge. But this may not solve out the problem of loosing fur on my circuits.

But the problem is much more complex than appears to be at a first sight. It looks like the cat himself is a sort of Electricity reservoir.

See:

http://jgp.rupress.org/content/jgp/43/4/713.full.pdf (http://jgp.rupress.org/content/jgp/43/4/713.full.pdf)
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: pert on Apr 15, 2018, 03:35 pm
There's a YouTube channel about electronics called scanlime (https://www.youtube.com/user/micahjd/videos). The cat is pretty much the star of the show and definitely has the run of the workbench. Whenever there's a closeup with the microscope camera sure enough you see plenty of fur on the circuits.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: ReverseEMF on Apr 15, 2018, 04:19 pm
Back in the early 80's I was building my own Altair style computer based on the Z80.  We called it the "cat computer" because our cat loved to curl up in the S-100 card cage, which was just the right size for him.


I suppose cat fur could be a problem with fans, or fan filters.  But, scattered fur has never damaged any of my electronics (though, it's been decades since I last owned a cat).
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Grumpy_Mike on Apr 15, 2018, 07:18 pm
When I designed set top boxes I had to talk with the returns department. They said the main source of damage from cats was water ingress sourced from the cat.

They will not cause static damage because the circuits are all connected up. It is only when electronic circuits are not wired up you get static damage. Or when thier is an input or output signal, but commercially at least these will be static protected.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: INTP on Apr 15, 2018, 07:39 pm
Static, bumping wires to short something out, eating or knocking away shiny things, they stink, and they track litter all over.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: larryd on Apr 15, 2018, 07:56 pm
Should be no problem.

(https://i.pinimg.com/originals/c2/c0/e1/c2c0e1a7e1c23654bec7fae06aee8a54.jpg)


Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 08:09 pm
@Larryd: but that cat is grounded :-)

Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Johan_Ha on Apr 15, 2018, 08:17 pm
I have a cat and though I can feel the electricity in her fur, I never get sparks from her. And she never seems to get sparks from any objects the way I get. Probably because she walks around grounded, while I wear shoes. And just some cat hair on your pcb can't do any harm. It's not conductive.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: larryd on Apr 15, 2018, 08:28 pm
@Larryd: but that cat is grounded :-)
True that is.



You could always get a Rex when the current fur ball is gone :(

(http://www.barenuddlessphynx.com/image/102370726.png)


Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 08:39 pm
@johan_Ha : then why I destroyed my printer by brushing the electronic components?
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: ReverseEMF on Apr 15, 2018, 08:46 pm
I have a cat and though I can feel the electricity in her fur, I never get sparks from her. And she never seems to get sparks from any objects the way I get. Probably because she walks around grounded, while I wear shoes. And just some cat hair on your pcb can't do any harm. It's not conductive.
I occasionally got a shock from my cat -- which would startle us both!  But, I was living in a desert, where the air got exceptionally dry -- especially in the winter!

But, Grumpy_Mike is correct, electrostatic discharge should not affect electronics where the "circuits are all connected up".  On the other hand, ESD could damage parts, not in circuit, if not handled with proper ESD protocol.

And BTW: even if a part, exposed to ESD, still functions, it's still possible is was damaged in a way that it will fail long before MTBF.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Johan_Ha on Apr 15, 2018, 08:48 pm
@johan_Ha : then why I destroyed my printer by brushing the electronic components?
Your brush wasn't antistatic.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 15, 2018, 09:11 pm
Well, neither the cat is. So, if the cat rubs against the circuit, it may happen the same as in the case of the brush. I am very confuse now.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Grumpy_Mike on Apr 15, 2018, 09:16 pm
@johan_Ha : then why I destroyed my printer by brushing the electronic components?
You probably didn't, it was something else.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: INTP on Apr 15, 2018, 09:33 pm
I don't imagine the smell of cat hair blowing by your soldering iron to be a pleasant smell.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Johan_Ha on Apr 16, 2018, 05:59 am
I was only imagining the cat touching the board, not rubbing it. Rubbing it will most certainly charge it. And a board is easily charged.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 16, 2018, 07:09 am
To this moment, it looks like the risk to damage the circuit is low unless the cat does not adopt an active/aggressive behavior against the boards/components.

O measured the cat by a multimeter:
- the resistance between the ears is higher than then meter range
- same for between the forefront paws
- the voltage between the ears is variable - in the range of 0,10 to -0.01  V- and varies in time (perhaps because of the movement - cat does not like probes in his ears)
- same variable voltage between the forefront paws

Therefore, the cat may present some electric potential (which I expected), but I have no posibility to measure the electric field as such.

   
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: INTP on Apr 16, 2018, 07:12 am
You have to break the skin to get some continuity.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: falexandru on Apr 16, 2018, 07:23 am
Or to fix the probe somehow, like the  human EKG.

There are three separate electricity issue with the cat, as far as I understand now:
a) electrostatic field (assumption: more intense if rubbing)
b) static electricity (potential) - assumption: impact only if un-furred areas touch the circuits
c) electricity pulses - when the cat moves - uncertain at this moment

Un-explored: cat licking the Arduino board. My cat loves to lick, so is not an imaginary situation.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Johan_Ha on Apr 16, 2018, 09:12 am
Meet Maggis.

(https://forum.arduino.cc/index.php?action=dlattach;topic=541634.0;attach=253643)

Maggis is sitting on a box, which is becoming a midi controller. At the left you see a glimpse of a prototype to a midi guitar. Maggis frequently pays attention to my work with electronics. And she rubs herself against my laptop screen.

Just thought this thread needed some images.


Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: jendalinda on Apr 16, 2018, 09:14 am
What about some conductive pad on the table?
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: Johan_Ha on Apr 16, 2018, 09:17 am
A grounded conductive pad? If I were afraid of actual damage, that would be a good idea.
Title: Re: Are cats dangerous for electronic circuits? (this is a serious question)
Post by: jendalinda on Apr 16, 2018, 09:21 am
Yes, your table and everything on it will be grounded.