Practical use of resources: 1.5 K resistor, 22 u capacitance, LOTO oscilloscope, adjustable PWM wave,

note: the choice of resistance and capacitance value does not need to be accurate, is actually compose a low-pass filter cutoff frequency is very low, for example, we selected above value is equivalent to a cut-off frequency of 4.8 Hz low-pass filtering,







Video in the discussion and practice of the two methods, the first is a software control OSC482 duty cycle of the PWM adjust the size of the RC filter to produce dc, the second is through S02 produce square wave signal source module, manually adjust the amplitude change of dc size of square wave,


The video link below
https://www.bilibili.com/video/BV1de411W7LT


Consider: after practice can obviously with adjustable resistance partial pressure to an adjustable dc to dc, why want to use this method to generate the dc PWM + RC filter?