[sdiy] Wanted: non mathematical description of the function ofRC-filters

[David G Dixon]

I think I understand the motivation here: math is always hard, and
therefore, any math-based description is going to fly right over the heads
of noobies.  However, IMHO, the operation of a filter is SO MUCH EASIER to
understand from a mathematical viewpoint that it is easiest just to teach
the math.  I didn't really understand filters myself until I took myself
through the mathematical analysis of current flow.

Do as the others have suggested: start with a voltage divider, and DEVELOP
THE MATH for it.  You can always relate it to pipes carrying water, if that
helps conceptually.

Next, replace one of the resistors with a capacitor, and introduce the
capacitor's impedance function, which is inverse to frequency.  Draw graphs
based on the math (the transfer functions) to show how the resistance
through the capacitor goes down as the frequency goes up.

Next, swap the resistor and capacitor.

As a professor of engineering, it has always been my experience that
students never really learn until their resistance to learning is broken
down.  When a student says that he or she wants to learn something, but then
puts conditions on how they are prepared to learn it, that usually means
that they don't really want to learn it.  Electronics is math.  The sooner
noobies understand that, the faster they can learn it properly.