[Hallicrafters] Piesoelectric effect case in point.

[Carl]

Interesting article but I get a kick out of the "severe drift" comment of up 
to 15%. That means diddly squat for our applications in bypassing and 
coupling. Class 2 and 3 have legitimate purposes in our BA's as do NPO where 
needed. Electrolytics of -50/+100 tolerance hasnt raised the ire of the 
obsessed here yet; they are use as a bypass cap.

I wasnt aware that ceramic was now available in values to compete with 
electrolytics and of course at those values ESR comes into play.

Carl
KM1H


----- Original Message ----- 
From: "Peter Bertini" <radioconnection at gmail.com>
To: "Glen Zook" <gzook at yahoo.com>
Cc: "rbethman" <rbethman at comcast.net>; <hallicrafters at mailman.qth.net>
Sent: Sunday, January 02, 2011 4:39 PM
Subject: Re: [Hallicrafters] Piesoelectric effect case in point.


> Hello to the group...
>
> I have been very careful in stating that the Piezo effect probably would
> cause any noticable problems in boatanchor gear. But, even the 
> manufacturers
> acknowledge that it exists, and the reasons:
>
> http://my.execpc.com/~endlr/ceramic.html
>
> Unfortunately this thread has taken so many turns and branches that it is
> impossible to follow and know exactly what is being replied to at this
> stage; thus I am begging out of further discussions. My only point was 
> that
> capacitors have specific electrical traits and one size doesn't fit all.
>
> 73 to all, and a Good New Years to everyone.
>
> Pete
>
> On Sun, Jan 2, 2011 at 4:31 PM, Glen Zook <gzook at yahoo.com> wrote:
>
>> There may not be any way that a ceramic disc capacitor can become a
>> transducer, but I have, on very rare occasions, heard audio coming from a
>> disc ceramic capacitor that has been used for coupling in an audio 
>> circuit.
>>  Replacing the capacitor, usually with a "poly" type, has cured this
>> "problem".
>>
>> I have also run into an occasional problem where, when "tapped", a disc
>> ceramic capacitor did act microphonic and introduced the "sound" into the
>> audio chain.  Have run into this on both transmitters and receivers.
>>
>> Probably, replacing with another ceramic disc might have solved the
>> problem.  One that did not have whatever "defect" which caused it to act
>> like a speaker.  However, when I do experience this I just replace the 
>> disc
>> ceramic capacitor with a different type and go on to the next problem.
>>
>> Glen, K9STH
>>
>> Website:  http://k9sth.com
>>
>>
>> --- On Sun, 1/2/11, rbethman <rbethman at comcast.net> wrote:
>>
>> Having just researched ceramic capacitor construction, I don't see ANY 
>> way
>> that these would have the ability to become a piezo transducer, OR having
>> anything to do with these old boatanchors.
>>
>> You "may" want to do a bit of research also.  They also manufacture 
>> "dipped
>> ceramic" capacitors.
>>
>>
>>
>>
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