Filter calculations

[strungout]

Ok, this may sound wierd, but how do I read the results on my calculator when I use the corner freq formula?

The formula is f=1/(2*pi*R(M)*C(uf), the results is supposed to be in Hz but then I get stuff like 0.0033(bunch more numbers). Is that 33Hz, 3.3KHz or 33KHz?

Sometimes the results is much clearer like 1/(2*pi*0.001*2.2)=72,343...etc which is 72Hz (by AMZ freq corner calculator.

So, bring some light before I hit my big toe somewhere...

Ciao.

[spongebob]

The original formula can be a little bit difficult to use, but if you tweak the units a bit you get a version that's easier to use:

f [kHz] = 1000 / (6.28 * c [nF] * r [kOhm])

[strungout]

thnx makes alot more sense now.

[R.G.]

If you're using a calculator to keep the decimal point in the right place, you don't need the units crutches. Just use resistance in ohms and capacitance in farads. The result is in hertz.

What will you do when you accidentally get a result that's really 0.00223Hz? Restore the decimal point to where you think it ought to be?

I strongly disagree with the use of special calculator pages by beginners. It may make one or two calculations for you, but it impedes and ultimately prevents the process of gaining understanding of the underlying calculation.  A person generally doesn't learn until they make a few mistakes and *understand* how and why they made them.