What would a ferrite choke do to a PWM signal?

[supak111]

Trying to understand what the waveform of a 12kHz PWM would look like if you put a ferrite rod choke on it?

Saw a guy doing an experiment where he took a 7 inch long, 1/2 inch diameter ferrite rod and wrapped 18 awg wire around it end to end. Than he pulsed a 12v PWM at around 12khz through it. What would the end signal look like?

 

[Harald Kapp]

The ferrite is a lossy inductor. The edges of the signal will be slowed and show ringing. The intensity of the effect depends on the specific properties of the ferrite and the number of turns of te winding.

 

[supak111]

So PWM's DC square wave after a large choke like the one I describe above will end up looking more like a sine wave?

 

[Harald Kapp]

More or less.