I have a RC filter on which I need to increase the capacitance. I have one 47uF ceramic capacitor and 2 47uF aluminum electrolytic ones at home. Can I use these in parallel in the RC circuit? Thank you for your help!
For a low-pass filter for PWM where the voltage is always the same polarity yes, you can use multiple electrolytics:
You might also consider a "Pi" RC circuit:
For lower losses it is better to replace the resistor with a suitable inductor to make an LC circuit.