TECHNET Archives

July 2018

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Wed, 18 Jul 2018 20:51:26 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (55 lines)
  
  


  
  
  
    
    	
    	Lol,
If your theory is correct the “fluid stream” would follow the laws of fluid dynamics which it doesn’t since for the flow (current) to increase for a given resistance the pressure (voltage) would have to increase which is exactly the opposite of Bernoulli’s laws.
And yes an ageing capacitor does resemble a balloon in capacity terms.
Best regards.
John
    	

    	Sent from my iPad Pro
    
  
From: 30171501600n behalf of 
Sent: Wednesday, July 18, 2018 1:41 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.
>

ATOM RSS1 RSS2