Effects of vibration on capacitors

D

David Harper

Jan 1, 1970
0
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave
 
D

Dan Major

Jan 1, 1970
0
[email protected] (David Harper) wrote in
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?
Caps and resisters should not be affected by vibration. They are
monolythic (solid) devices. OK, "should not be affected..." up to a point.
If you get vibration that causes g forces great enough to cause mechanical
breakdown of the physical packaging, *then* the values will change. Other
components, however, will be affected because they are either mechanical in
function (crystals), or are such that the shape can be easily changed
(coils, etc.). I suppose if the components were surface mounted on a
circuit board that was flexible enough, and the vibrations caused the
components to bend or otherwise change shape *then* caps and resistors
could change value.
 
B

Bob Stephens

Jan 1, 1970
0
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave

Depends on the capacitor. "Condenser" microphones convert vibration into a
proportional voltage intentionally.


Bob
 
L

Leon Heller

Jan 1, 1970
0
David Harper said:
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Some ceramic capacitors exhibit a piezo-electric effect. Try putting a
'scope across one and tapping it (the capacitor, not the 'scope).

Leon
 
G

Guy Macon

Jan 1, 1970
0
David said:
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Capacitors don't regulate voltage. Do a Google search on "voltage
regulators." Also. most capacitors will fail because vibration
breaks them or the board they are on long before their electrical
characteristics will change. (We are talking about a lot more
vibration than you will find in a model rocket).
 
J

John Popelish

Jan 1, 1970
0
David said:
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave

I've already told you about the bad actors. But even those usually
only cause problems in high impedance circuits (integrators, filters,
coupling etc.) Used as power supply bypass, there are usually several
in parallel and in parallel with a low impedance supply, so their
small microphonic currents get absorbed across other loads. There is
little chance that all the caps across the line would experience
exactly the same vibration, in phase, and add. Your big problems in
high vibration environments will be lack of physical ruggedness,
resonance with the vibration, and lead breakage.
 
D

David Harper

Jan 1, 1970
0
Dan Major said:
[email protected] (David Harper) wrote in

Caps and resisters should not be affected by vibration. They are
monolythic (solid) devices. OK, "should not be affected..." up to a point.
If you get vibration that causes g forces great enough to cause mechanical
breakdown of the physical packaging, *then* the values will change. Other
components, however, will be affected because they are either mechanical in
function (crystals), or are such that the shape can be easily changed
(coils, etc.). I suppose if the components were surface mounted on a
circuit board that was flexible enough, and the vibrations caused the
components to bend or otherwise change shape *then* caps and resistors
could change value.

Yes, they are solid state devices that "assume" the distance between
charge holders will remain constant. With vibration, if you have a
few microns displacement between charges, that could result in a small
voltage deviation, correct? The question I'm concerned with is "how
much"?

Thanks,
Dave
 
P

Pooh Bear

Jan 1, 1970
0
David said:
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Well, actually capacitors don't *regulate voltage* in the first place.

The capacitance can vary with vibration - which can have implications
depending on the circuit the capacitor is placed in. It won't have any
effect of significance for power supply decoupling - if that's what you
mean.

The least affected caps are probably plastic film types.



Graham
 
P

Product developer

Jan 1, 1970
0
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave

In coupling high gain amplifier stages beware of microphonics using
the wrong capacitor type.
 
R

Ross Herbert

Jan 1, 1970
0
Does anyone know how severely vibration can affect a capacitor's
ability to regulate voltage? (i.e. how much the voltage can deviate
as a function of vibration) What types of caps are better at
regulating voltage under high vibration?

Thanks in advance!
Dave

You aren't really serious, - or are you?

Let us assume you are and have a practical reason for knowing...

You are referring to "regulating voltage" and since the main use of
capacitor's in this role will be electrolytic types, then we can make
general observations. Generally speaking, electro's for voltage
smoothing/storage will have fairly large values at the appropriate
voltage rating dependant upon the load requirements, so they are
usually fairly bulky unless you are talking smd.

Any device, whether passive or active has mass and where it is known
that components will be subject to vibration, they must be adequately
secured and prevented from movement and placing any stress on their
mounting (pins, pads, whatever). Since the mounting part is the one
which suffers most during vibration it will eventually fracture unless
adequate precautions are taken when mounting. Other than the physical
aspect of preventing any movement, all passive components will be able
to handle extremely high g forces without any effect on their
operational characteristics.

In your later post in response to Dan Major you say that caps and
resistors are "solid state devices" but this is plainly incorrect. You
talk about about a "few microns displacement" and "charge holders" but
these factors have abolutely nothing to do with passive components of
the size and bulk of electrolytic caps. And due to the magnitude of
the voltages and currents they are handling any sub-micron movement
between the plates - (assuming that movement could in fact occur,
which it doesn't) - would not be noticeable and would therefore have
no effect whatsover on regulating ability.

Are you sure you are not just trolling?
 
R

Ross Herbert

Jan 1, 1970
0
Capacitors don't regulate voltage. Do a Google search on "voltage
regulators." Also. most capacitors will fail because vibration
breaks them or the board they are on long before their electrical
characteristics will change. (We are talking about a lot more
vibration than you will find in a model rocket).


What? Of course they regulate voltage...

What do you think the designers of old (and even today) used to
maintain a stable voltage supply without using an active regulator?
Yes, a bloody big capacitor, - and it still works surprisingly well.
 
T

Tim Wescott

Jan 1, 1970
0
Dan said:
[email protected] (David Harper) wrote in



Caps and resisters should not be affected by vibration. They are
monolythic (solid) devices. OK, "should not be affected..." up to a point.
If you get vibration that causes g forces great enough to cause mechanical
breakdown of the physical packaging, *then* the values will change. Other
components, however, will be affected because they are either mechanical in
function (crystals), or are such that the shape can be easily changed
(coils, etc.). I suppose if the components were surface mounted on a
circuit board that was flexible enough, and the vibrations caused the
components to bend or otherwise change shape *then* caps and resistors
could change value.
High-dielectric constant ceramics certainly pick up vibration long
before anything breaks, and no matter how much you scold them they do
not stop.
 
A

Andy

Jan 1, 1970
0
David Harper said:
Yes, they are solid state devices that "assume" the distance between
charge holders will remain constant. With vibration, if you have a
few microns displacement between charges, that could result in a small
voltage deviation, correct? The question I'm concerned with is "how
much"?

Hello Dave,

If you cross section a variety of capacitors of the various designs you'll
probably find that micron scale tolerances grossly dwarfed by the distances
between other key features (i.e. plate gaps, dielectric bulk impurities,
etc.).

Are you grappling with a voltage regulation problem during vibration?
Glitches or drift? If you're are dealing with glitches, I'd suggest you
look at your non-soldered interconnects -- Even your pins and sockets.
Especially your pins and sockets if you've made several (de)mates. Without
looking at your application, I'm a bit hard pressed to guess why you may be
seeing voltage drift during vibration although spooky ideas such as stray
coupling comes to mind.

Do we get anymore clues?

Best,
Andy
 
D

David Harper

Jan 1, 1970
0
Ross Herbert said:
You aren't really serious, - or are you?
Yes.

Let us assume you are and have a practical reason for knowing...

You are referring to "regulating voltage" and since the main use of
capacitor's in this role will be electrolytic types, then we can make
general observations. Generally speaking, electro's for voltage
smoothing/storage will have fairly large values at the appropriate
voltage rating dependant upon the load requirements, so they are
usually fairly bulky unless you are talking smd.
Ok.

Any device, whether passive or active has mass and where it is known
that components will be subject to vibration, they must be adequately
secured and prevented from movement and placing any stress on their
mounting (pins, pads, whatever). Since the mounting part is the one
which suffers most during vibration it will eventually fracture unless
adequate precautions are taken when mounting.

The time spent under high vibration for the life of this project will
be minutes, at most. I'm not worried about lead or solder fatigue.
Other than the physical
aspect of preventing any movement, all passive components will be able
to handle extremely high g forces without any effect on their
operational characteristics.

In your later post in response to Dan Major you say that caps and
resistors are "solid state devices" but this is plainly incorrect.

He stated they were solid state devices, so I just went along with it.
My apologies.
You
talk about about a "few microns displacement" and "charge holders" but
these factors have abolutely nothing to do with passive components of
the size and bulk of electrolytic caps.

Pardon? You're stating that if you took a charged cap, changed the
distance between the plates and measured the voltage across it while
doing so, there'd be no change in voltage at all?
And due to the magnitude of
the voltages and currents they are handling any sub-micron movement
between the plates -

Compare that "sub-micron" movement with the actual thickness of the
dielectric material. It is very thin to begin with. A few microns of
compression of the dielectric could be a small percentage of the
thickness of the dielectric. I didn't know. THAT'S WHY I ASKED.
(assuming that movement could in fact occur, which it doesn't)

You statement implies the dielectric would be infinitely hard and
incompressable. No substance is.

- would not be noticeable and would therefore have
no effect whatsover on regulating ability.

Well, I tried this for myself. Using a speaker and running several
different frequencies through it (with the cap attached through a
linkage 10" away), the oscope showed a clear voltage deviation. Some
frequencies (10kHz) were worse than others (500Hz). Maybe before
attacking someone's question, you may want to make sure you're not
making too many assumptions.
Are you sure you are not just trolling?

What about my question implied that I was looking for an argument?
I'm not sure if you were just in a bad mood when you replied, but it
was a civilized question, did not insult anyone, and had several
people talk about microphonics.

Dave
 
J

Jamie

Jan 1, 1970
0
David said:
Yes, they are solid state devices that "assume" the distance between
charge holders will remain constant. With vibration, if you have a
few microns displacement between charges, that could result in a small
voltage deviation, correct? The question I'm concerned with is "how
much"?

Thanks,
Dave
one of the places i do work for test their Mica Dips on 15G, thats a lot
of vibration. in that test there was no notice able problems 99.99%
of the time. now and then you may have one where the encasement does
not fully fill the voids or a bad crimp.
 
D

ddwyer

Jan 1, 1970
0
In coupling high gain amplifier stages beware of microphonics using
the wrong capacitor type.
Hi K ceramics are piezoelectric due to barium titanate? doping.
Hi the with a pulse and they can be heard to click.
By reciprocality they are excellent high freq microphones.
Hence use low k , electrolytic or plastic film for low noise.
 
W

Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
ddwyer said:
Hi K ceramics are piezoelectric due to barium titanate? doping.
Hi the with a pulse and they can be heard to click.
By reciprocality they are excellent high freq microphones.
Hence use low k , electrolytic or plastic film for low noise.

The only porovblem then becomes how to tell a hi K from a Low K. Like,
they con't come labeled as to that factor.

I suppose you could put them into a high gain amp circuit and plink on
them and see if they put out something. But then that's too easy, isn't
it.


 
G

Gene Costanza

Jan 1, 1970
0
....that everyone who replied to this question actually GAVE AN ANSWER!!!!! WHAT??!! No
politics, backstabbing or threats of prison sex?!

Huh, PHIL??!! :)>
 
S

Steven P. McNicoll

Jan 1, 1970
0
Gene Costanza said:
...that everyone who replied to this question actually GAVE AN
ANSWER!!!!! WHAT??!! No politics, backstabbing or threats
of prison sex?!

Huh, PHIL??!! :)>

Replied to what question? You began a new thread, there is no question.
 
T

Terry Given

Jan 1, 1970
0
Tim said:
High-dielectric constant ceramics certainly pick up vibration long
before anything breaks, and no matter how much you scold them they do
not stop.

Yet another reason to avoid the poxy things. Z5U, Y5V = shite.

Cheers
Terry
 
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