Outer Foil on Film Cap

Outer cap foil surface can pose as an EMI antenna or as a shield depending on if that pole corresponds more to 'damped' side of the circuit (that could cause problems, as frequencies go up), or more to signal ground. Is that's what you refer to? S.M.

But, how do I explain that in simple words? I have a hard enough time explaining capacitance. I know how to hook them up, but can't tell you why that does what it does.

Some things you just have to take on faith, baby.

I remember Pythagoras once said that once.

I have found that, "just because" sometimes satisfies them for awhile.

But the bright ones always come back.

I'm not into teaching (done it for a while in military tech environment) but my idea is that method of thinking is the final goal and not trying to explain every bit of information. Now depending on your audience 'simple words' can get different meanings and task isn't always that easy. Even the simplest project, if you try to exhaust it, you'll have to go to low level details, and even those require some audience background and so on. But you do have to stop somewhere. S.M.

If you had rotated it axially when you changed the probes It would have looked the same.

Don't worry, be happy.

So, is it just the outer layer that gives the difference? That I could explain.

Well, there's no fool like an educated fool. I've known about capacitors stripes for most of fifty years now. I've read about it in books, I'm been told in classes, and I've seen it when I've experimented. IT AIN"T REAL!

After I questioned how to really explain it, I started doing some research online. The old Sprague archives have been opened and, lo and behold, there's a tech note from an engineer that the stripe was merely an artifact that they used in production and it had nothing to do with the outer foil. In fact, the note says, most of the orange drop caps' outer foils can't even be identified by testing.

So, what did I see? They call it confirmation bias. Since I believed in the effect, I tended to look only at data that supported my belief and ignore data that didn't. Turns out this myth did me no harm, but what other myths do I believe in?

Has anybody given you the real scoop on Santa, yet?

Don't tell me about that old coot,

For years he's given me nothing but WorldCom stock and John Edwards bumper stickers.

In RFI propagation, a faraday shield acts as a limiter. The outer foil is the grounded one - in most cases a capacitor is an RF bypass to ground, to prevent feedback etc..

If it is a DC blocker to allow Ac signal to pass, it matters less because the connecting wires radiate, damped only by their matched impedance. The capacitance of the capacitor determines the pass band for stage to stage signal transmission

Yes.

And the outer foil is connected to ground.

Not only in capacitors but also the outer layer in transformers for signals circuits is used to be connected to ground.

Example is in signal transformers and single phase rectifiers outer-layerof secondary is connected to ground for the purpose.