[Hallicrafters] Piesoelectric effect case in point.

[Peter Bertini]

Ceramic disks use ceramic dilectrics.There are several types:

http://electronics.ihs.com/collections/abstracts/eia-198-1.htm

 Are you thinking of dipped mica caps?

Piezo effect means the capacitor can exhibit the characteristics
of a piezo transducer, not that is one.

Pete

On 1/2/11, rbethman <rbethman at comcast.net> wrote:
> Well, as Carl pointed out, first the proper spelling is piezo.
>
> I can see this with quartz.  The 1950's Shure element is one big slice
> of quartz.
>
> I'm having a problem with "ceramic"  What is the ACTUAL construction of
> "ceramic disk" capacitors?  In every application of "ceramic" materials,
> they don't work ANYTHING like quartz.
>
> The best of my knowledge, disk caps have been mica for the dielectric.
> The silver mica migration has come up quiye a bit over the years.
>
> Bob - N0DGN
>
> On 1/2/2011 3:23 PM, Roger (K8RI) wrote:
>>> Hi Walt
>>>
>>> That is interesting. I personally was never fond of ceramic disks in
>>> audio
>>> circuits, especially for coupling. But I never expected that the effect
>>> would be that pronounced. Thanks for the verification.
>>>
>> I wonder if this is truly a "piesoelectric effect" of the caps having
>> developed a mechanical defect that allows the capacitance to change
>> value with vibration, or mechanical shock, thus acting like a capacitor
>> microphone.  The results would be the same the mechanics are quite
>> different.
>>
>> 73
>>
>> Roger (K8RI)
>
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