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Old December 2nd 08, 06:22 AM posted to rec.radio.amateur.homebrew
Grumpy The Mule Grumpy The Mule is offline
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First recorded activity by RadioBanter: Sep 2008
Posts: 87
Default uses for exotic capacitor types?

Howdy,


Without seeing the parts I can only take a WAG at what the
capacitors in question might be. This web site might help.
http://www.faradnet.com/

UNKNOWN TYPE AND APPLICATION:
1. Blue, really shiny, flat, and small like a disc ceramic.


Possibly Murata (or others) ceramic capacitors designed for
use in AC line filters.

2. Orange and shiny- definitely not electrolytic or tantalum. Both
bulgy and flattish.


Possibly Sprage Orange drop polypropylene film capacitors. There are
various types in this product family. Generally good for high dV/dT
or pulse current applications like snubbers. Could be metallized film
or film and foil.

3. Green and shiny- both bulgy and flattish. (I've heard these are
either mylar or polyester film. How do I tell them apart?)


I think this is a good guess. Mylar is a polyester film.

4. Dark orange (maybe brownish?) and bulgy.


Another film capacitor. If brown possibly Panasonic polyester.

5. Yellow rectangular blocks.


It's a film capacitor, Possibly Wima. I can't remember what the
material is. Could be Philips polyester too.


KNOWN TYPE, UNKNOWN APPLICATION
6. Labeled "monolithic dip"- what do I use these for?


General low energy use, coupling, by pass and filtering.

7. "Mallory DC Film" (250V)- what do I use these for?


Polypropylene, bypass or noise suppression.

8. What's the difference between the following three types of mica
capacitors?


* Dipped silver mica
* Old-style micas (colored dots and physically large rectangular
blocks)
* Modern, not dipped-silver micas



Dipped mica is still made and good for RF coupling and snubbers. I use
these in antenna tuners.

The box type with dots are similar construction but with metal plates
instead of metalization. They're good for RF coupling and high current
like tank circuits.

The non-dipped I'm guessing Unelco metal clad which are more like the
box style without the box. Less series inductance so better high frequency
performance. I've used these in solid state linears up into the VHF range.


The film capacitors vary in the material, polyester (mylar) polyproylene,
polycarbonate, polystyrene and more exotic films like polysulphone...each
has its strong and weak points. Some use mixed dielectrics. The
construction can be metalized film, metal foil, double layer (self healing)
or stacked film. The method for attachment of the lead wires may vary too
with high current capacitors having thicker termination or schouping (sp?)
metal sprayed onto the ends of the foil or film. The Farad Net site
documents some of the types and applications.


As always YMMV. I'm just guessing.


73,
Grumpy