my intuition says that the outputting waveform should resemble something more like the actual 110Hz waveform pictured. Slower but with the same amplitude.
That is exactly how filters do not work.
All a filter will do is to lower the amplitude of a signal. The cut off frequency is the point where the signal is reduced by half. So if you have a filter with a cut off frequency of 10Hz and you put a frequency of 10Hz into it the output will be half the input.
If you put a frequency of 100Hz into a filter with a cut off frequency of 10Hz the output will be a 100Hz signal who's amplitude is cut down by a quarter. For each octave ( a doubling of frequency ) you get from the cut off frequency the amplitude of the output will drop by a half. So at 1KHz a filter with 10Hz cutoff frequency will be a half times a half times a half = one eighth of the origional amplitude.
All the filter does is reduce the amplitude of the input signal by an amount determined by how far the input frequency is away from the cut off frequency.
That makes sense yes. It's actually opposite of what i thought.
However i'm still somewhat confused as how exactly this correlates with this picture:
The picture is obvious. You have two frequencies...the higher pitched one will be filtered, and the lower will pass.
But if i have just one (unmodulated) frequency, and i apply a filter...i'm going to get just the attenuation of the signal as you described. Am i understanding this correctly?
Somebody mentioned using a high-fi and the equalizer to filter out treble for instance. In this case the audio signal is heavily modulated and contains all sorts of frequencies (fro 20Hz to 20kHz).
Hmm, on second though that's actually it. If only the base is left, and then you start to slide down that, you'll basically be "turning down the volume".
What are the sliders doing technically..."adjusting" the RC components of the filter?
The base line...lets say has a range from 20Hz to 200Hz, is the slider basically increasing the low pass filter cut-off value from 0Hz to 200Hz?
So trying this with the PWM signal. 100Hz, 100% duty PWM signal would yield a halved amplitude, but still 100% duty, if i put a 100Hz filter on it. So 5V down to 2,5V?
Same with 50% duty. It'd get 2,5V for half cycle.
The average i was talking about is not actually a true average. It would be that, only if i used a 100Hz low-pass filter on a 100Hz signal, right?
Please pardon the complications, but this issue is somewhat bugging me. :)
As far as i know a PWM is juts a purely positive (or negative) square waveform with a cycle that can be from 0-100%. O% means constantly OFF (low), 100% constantly ON (high)...and let's say 80% is...80% of the cycle ON and 20% OFF.