[sdiy] VCO saw integrator cap questions

[Ian Fritz]

At 12:21 AM 9/21/2009, David G. Dixon wrote:
>What about C0G monolithic ceramics?  They are
>supposed to be extremely stable with temperature.  Why don't we use them for
>VCOs?

Those are what I use now, as I've mentioned here several times.  I've 
compared them against polystyrene is several designs and they work just as 
well.  Additionally, one occassionally runs into bad polystyrenes, and they 
are easy to damage with heat, which has given a number of builders problems.


>3) I get ceramic caps from my school, and they are these pretty little blue
>things, some only about 3 mm wide and maybe 1.5 mm thick, with white
>markings (I think they're EPCOS, supplied by Digikey).  They are C0G in
>smaller values (up to 2n2), and typically have 0.1" lead spacing, although
>some are 0.2".

Yes, those are the ones.  Just put them in marked containers when you get 
them you will always know they are C0G.  They are small because of their 
multilayer construction and relatively low voltage rating.


>I use them for coupling, bypassing, and speed-up
>applications, but never for timing (integrators, filters, etc).  Could I?
>Should I?  They seem to work perfectly well.

Yes you could/should.  Yes, yes.

Ian