Others have posted good replies already, hope they've helped to connect the=
 dots=20
for you.

Once the underlying principals are learned I suspect each of us summarizes =
and=20
simplifies our own knowledge with a mental picture or general analogy that =
seems=20
to suit. For me it's this: capacitors and inductors are essentially opposit=
es in=20
function, a capacitor attempts to maintain a constant voltage accross it's =
terminals=20
and does so by changing the current flowing through itself, an inductor att=
empts to=20
maintain a constant current flow and does this by changing the voltage acro=
ss itself.

> Capacitors:
>=20
> I'm trying to (fully) understand the principle of capacitor reactance and
> high pass filters. I'm having trouble forming a mental picture of how a
> capacitor in series with a signal blocks DC and has the lowest impedance
> for the highest frequency signals on a voltage and charge-on-the-plate
> level. I can understand how a capacitor tied to ground acts as a buffer a=
nd
> smoothes out high frequencies by averaging the voltage. But I don't reall=
y
> get how the reverse is true for a capacitor in series with a signal. I ca=
n
> see how it blocks DC after it is fully charged.
>=20
> 1. How does a capacitor in series work to block a DC signal, but pass a
> high frequency signal?
> 2. If you apply a voltage to a capacitor in series (keeping in mind that =
it
> takes time for the voltage from the power source to rise), I understand
> that the current before the capacitor is NON-zero. But what about the
> current AFTER (on the other side) of the capacitor? Is it zero or non-zer=
o
> (considering that a capacitor is just two parallel plates)?
>=20
>=20
> LC circuits:
>=20
> 1. Consider a parallel LC circuit where the bottom is tied to ground and
> the top is tied to a mixed-frequency signal source. I understand that the
> parallel LC circuit will shunt all frequencies to ground other than those
> around its resonant frequency. After the signal source is removed, the
> circuit will eventually lose its energy. How do I make an oscillator out =
of
> such an LC circuit that self-starts (that is, I can simulate in LTSPICE
> which doesn't take into account external noise coming into an oscillator
> circuit, which is required for some oscillator designs)? I've looked at L=
C
> oscillator circuit types like the Hartley oscillator, but I don't see how
> this can self start in theory under ideal conditions.


--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.