It's not clear why one would make this distinction. The time and frequency domain representations of a physical signal are mathematically equivalent. If one is physical the other is by definition.
So a pure sine wave is a graphed unit circle?
The DC component is the average of the duty cycle? I'm still having trouble understanding why then we set our cut-off frequency to 0Hz? Don't we need the voltage to toggle between 0V and 5V in order to achieve PWM?
Do we dare speak of Butterworth, Bessel, Chebychev, elliptic etc?Allan
Hi GangWell I printed out the thread today and read it thoroughly. I was hoping that it would clarify things however it's raised more questions.
1. If I want to calculate the impedance of the circuit shouldn't I be using the PWM frequency (490Hz) in order to calculate the reactance of the capacitor?
3. How do I know whether the device I'm feeding my filtered signal to is drawing current?
4. I'm still unsure about component selection. In post #29 septillion touches on the subject but I don't quite follow. Wouldn't I be interested in the acceptable ripple voltage rather than the ripple frequency? Could you expand on this?
5. The PWM signal constantly changes based on how strong the Received Signal Strength Indicator (RSSI). I imagine I need to balance responsiveness and ripple?
6. If I increase the frequency and reduce the resistor/capacitor size I gather that means the capacitor can charge/discharge quicker hence the better response?
7. If I was to use DAC what would be a good starting point?
If I put a hot soldering iron tip on a circuit board, and the temperature on that part of the circuit (where the hot iron tip is touching) abruptly rises from 25 degrees C to some relatively high temperature value. Yep...assuming this is happening in the real world, in the time domain. Better not tell anybody that the temperature rise at that part of the circuit is physically (actually) a bunch of sinusoids all individually ganging together at the same time.
Maybe you're being subversively ironic, but the Fourier Transform as we know it was introduced in Joseph Fourier's seminal manuscript on heat transfer to analyze essentially the scenario you describe.
Jean-Baptiste Joseph Fourier - (/ˈfʊəriˌeɪ, -iər/; French: [fuʁje]; 21 March 1768 - 16 May 1830) was a French mathematician and physicist born in Auxerre and best known for initiating the investigation of Fourier series and their applications to problems of heat transfer and vibrations.
This firestorm of posts was only triggered by someone deciding to pointlessly argue over a distinction without a difference.
5. The PWM signal constantly changes based on how strong the Received Signal Strength Indicator (RSSI). I imagine I need to balance responsiveness and ripple?6. If I increase the frequency and reduce the resistor/capacitor size I gather that means the capacitor can charge/discharge quicker hence the better response?
On the other hand, if you have any given waveform (periodic or not), your signal is and can be expressed as a sum of sines and cosines at different frequencies...