What is also fun is learning something new every time I open a Technet post.
Ken Barton CID
Technical Designer,
Avionics HW
Blue Origin, LLC
21218 76th Avenue S.
Kent, WA 98032 (253) 437-5625 x5625
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D
Sent: Wednesday, July 18, 2018 3:14 PM
To: [log in to unmask]
Subject: [EXTERNAL] Re: [TN] capacitor measurement
We wish it were simpler.
Current does not actually "flow" from plus to minus, nor from minus to plus. Rather, it is a simultaneous electron/hole flow recombination across the entire conductor. It all depends on how you look at it. The physicists still argue about this. They always will.
The tank or water balloon you are referring to is called a dielectric or dielectric plates.
And furthermore, engineering really is quite simple; it is nothing more than learning to use different tools to control various energies or energy sources that are all trying to reach equilibrium. Electronics is nothing more than using electrical or electronic components to control differences of electrical potential (both positively and negatively charged) trying to achieve 0 volts. Hydraulics and fluid dynamics is nothing more than using various tools to control liquid forces trying to reach 0 pounds per square inch of pressure. Hot things want to reach room temperature, or at least the temperature of the air around it. So do cold things. So do magnetic fields. So does light energy. So do chemical reactions, etc., etc.
Understanding all of that is quite simple. The hard part is learning and memorizing methods, the units of measurement and the calculations for control, and the ratings of the components, valves, light meters, emission rates, cooling rates, ad nauseum.
Sometimes, very nauseum.
But once you have mastered that, it's fun!
Archimedes said "Give me a place to stand, a solid fulcrum, a lever long enough, and I can MOVE the world!"
Electrical engineers say "Give me a good electrical ground, plenty of power and wire, sufficient capacitance and shielding, and I can CONTROL the world."
dean
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dennis Fritz
Sent: Wednesday, July 18, 2018 3:42 PM
To: [log in to unmask]
Subject: Re: [TN] capacitor measurement
Ahhh, those blank, blank electrical engineers again. Why can't it be
simple? Current is a flowing fluid stream, just electrons not water.
Resistors are valves that increase or decrease the flow. Capacitors are
tanks where the fluid flow is stored. And now you are telling me the tank
size varies with age and temperature. What are you electrical guys using for a tank - some kind of water balloon or something?
On Wed, Jul 18, 2018 at 4:04 PM Wayne Showers <[log in to unmask]>
wrote:
> What has been described is all good information, but here is the yeah but:
>
> At design:
> Voltage coefficient is the largest concern and for this reason, each
> cap should be overtightened and then loosened. General Rule I follow
> in RC circuits is to try to keep the capacitance as low as possible to
> counteract the effects of aging.
>
> In production testing:
> So long as the specifications are known, I use a variant of the old
> Mil-R-39008 (Carbon Comp Resistors) which is group average of 2X
> tolerance and for individuals, 3X tolerance. This has been effective
> in limiting both bad product and test failures. I also target testing
> at 60Hz for capacitors to limit capacitance depression from higher
> frequency and/or source impedance.
> These attributes will limit false rejections at Incoming Inspection
> and ICT.
>
> As for 'refreshing' capacitors:
> Baking above the Curie point is not always possible or for that matter
> even desirable, so I only ever did this on a limited basis.
>
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