On Tue, 21 Aug 2018, wrote:

In rec.radio.amateur.homebrew Phi wrote:

wrote in message
...
In rec.radio.amateur.homebrew Phi wrote:

"Gareth's Downstairs Computer"
wrote in message
news You know, the ones in the clear plastic blobs, wire
ended with low puffage values and reputed to be super
stable?

Silver mica were the best.

Got any 1,000 uF silver micas?

--
Jim Pennino


Perhaps you forgot or don't know, they are not electrolytic.

Neither silver mica nor polystyrene capacitors are electrolytic.

What's your point?

Perhaps you forgot or don't know that in general polystyrene capacitors
are advantageous at audio frequencies while silver micas are advantageous
at RF frequencies and fill two entirely needs.

Read this:

https://en.wikipedia.org/wiki/Film_c...ilm_capacitors

Except "1,000uF" is a large value of capacitance, more in line for audio
than RF. At that value, virtually everyone shifts to an electrolytic
capacitor since it's the only way to get the value cheap and in a
reasonably sized package.

I admit to misreading it when I read it first, me thinking "1,000 pF"
which of course is .001uF and a value not common for the sort of thing
being discussed. It's a common RF bypass value, where you wouldn't need
an exact value and hence no need for polystyrene capacitors. Yes, I know
there are exceptions, but generally it is a high value for RF frequency
control purposes.

As for what happened to them, they came "late", and then I thought they
had just sort of morphed, either under a different name or something else
came along that was equivalent, but I admit I've not paid attention.

Michael