The point was to share findings and hope for more discussion. Not all here are engineers whose primary job is electronics. Me amongst them. What is obvious and well known to you may not be even clear to others.
Whoever, junior or senior, wrote the piece had more knowledge than I did. I found it and I share with diyers. It is up to you if you use it.
DF96, you seem to have deep knowledge, so share it with me / us.
Back to topic, I can see clearly how electrolytic or film caps respond to signal in function of DC voltage across it. It proves you were right and that is the point no. 2
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I have (for too long time 
) planned to measure 3rd harmonics from caps using a signal generator (1kHz) a twin-T filter tuned to 1KHz and a RMS V-meter.
You simply measure the signal through the filter without a cap and calibrate the V-meter for zero reading. Add a cap and you should see harmonics give a reading.
It could be a piece of cake to attach a voltage supply across the cap and see if that adds harmonics.
Have to add this to my "must-do list".
) planned to measure 3rd harmonics from caps using a signal generator (1kHz) a twin-T filter tuned to 1KHz and a RMS V-meter.You simply measure the signal through the filter without a cap and calibrate the V-meter for zero reading. Add a cap and you should see harmonics give a reading.
It could be a piece of cake to attach a voltage supply across the cap and see if that adds harmonics.
Have to add this to my "must-do list".
Distortion from all except the very worst caps is quite small so you will have difficulty in measuring it. The twin-T filter, assuming it will be boostrapped, may produce more distortion than many capacitors. And the filter will include caps itself.
Think of it like this: how would you measure inaccuracies in a ruler when all your measuring equipment is based on rulers?
Think of it like this: how would you measure inaccuracies in a ruler when all your measuring equipment is based on rulers?
Well, I cvalibrate my equipment with all parts EXCLUDING the caps connected. Whatever I add to my setup in the next step will be measured.
I have a RMS-meter capable of measuring down to at least -120dB. IF a cap is bad enough it is detectable.- This setup is/was used when measuring so called Klirr, 3rd harmonic distortion.
I have a RMS-meter capable of measuring down to at least -120dB. IF a cap is bad enough it is detectable.- This setup is/was used when measuring so called Klirr, 3rd harmonic distortion.
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