Effects of vibration on capacitors

Effects of vibration on capacitors

Post by Dan Majo » Sun, 14 Nov 2004 00:18:01





Quote:
> 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.

--
Sooner dot boomer at gbronline dot com

 
 
 

Effects of vibration on capacitors

Post by Bob Stephen » Sun, 14 Nov 2004 00:49:32



Quote:
> 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

 
 
 

Effects of vibration on capacitors

Post by Leon Helle » Sun, 14 Nov 2004 01:20:46



Quote:
> 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

 
 
 

Effects of vibration on capacitors

Post by John Popelis » Sun, 14 Nov 2004 01:46:20


Quote:

> 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.

--
John Popelish

 
 
 

Effects of vibration on capacitors

Post by Guy Maco » Sun, 14 Nov 2004 01:42:21


Quote:

>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).
 
 
 

Effects of vibration on capacitors

Post by Pooh Bea » Sun, 14 Nov 2004 06:38:24


Quote:

> 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

 
 
 

Effects of vibration on capacitors

Post by Product develop » Sun, 14 Nov 2004 07:10:31


Quote:

> 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.
 
 
 

Effects of vibration on capacitors

Post by David Harp » Sun, 14 Nov 2004 05:01:21


Quote:



> > 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.

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

 
 
 

Effects of vibration on capacitors

Post by Tim Wescot » Sun, 14 Nov 2004 11:26:09


Quote:



>>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.

High-dielectric constant ceramics certainly pick up vibration long
before anything breaks, and no matter how much you scold them they do
not stop.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 
 
 

Effects of vibration on capacitors

Post by Andy » Sun, 14 Nov 2004 13:34:40



Quote:




>> > 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.

> 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

- Show quoted text -

Quote:
> Thanks,
> Dave

 
 
 

Effects of vibration on capacitors

Post by Jami » Mon, 15 Nov 2004 05:07:10


Quote:

> 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 enca***t does
not fully fill the voids or a bad crimp.
 
 
 

Effects of vibration on capacitors

Post by ddwye » Mon, 15 Nov 2004 06:16:58


Quote:
>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.

--
ddwyer

 
 
 

Effects of vibration on capacitors

Post by Watson A.Name - » Mon, 15 Nov 2004 08:07:44



Quote:
> >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.

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.

Quote:
> --
> ddwyer

 
 
 

Effects of vibration on capacitors

Post by Gene Costanz » Mon, 15 Nov 2004 08:22:20


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

Huh, PHIL??!! :-)>