How can i get an average voltage of square wave output voltage using low pass filter?

Question

Thanks for the answers. my output voltage has multilevel steps. ie, for example the output voltage is 30V from 0 to 50ms, 20V from 50ms to 100ms and 10V from 100ms to 150ms. I know i can easily measure it using Oscillscope but i want a circuit which gives me the average of the above multilevel output voltages.

Answer 1

i think this will work - no promises

the output from a suitable low pass filter will yield a rough sinusoidal shaped positively biased wave

pass this thru a "large" "series (ac) cap" which will remove most of the dc component and then buffer it and then measure the resultant voltage with a true rms meter

if it is a "true" rms  meter the wave shape should not make a difference  so you can skip the low pass filter

Answer 2

Much easier to measure it directly without the LP filter, which will probably change the reading.

Question 1, do you want average or RMS voltage?

Question 2 is this square wave swinging from +V to -V or 0 to +V

Question 3 is this square wave 50% duty cycle?

RMS:

You can use a true RMS meter, or an oscilloscope.

Re scope, if it is actually a 50% duty cycle square wave, centered on ground, then the RMS is equal to the level of the + peak voltage.

Average:

if it is actually a 50% duty cycle square wave, centered on ground, then the average is zero. If the square wave swings between zero and +10 volts, and the duty cycle is 50%, then the average is 5 volts.

If the duty cycle is not 50%, then it's DC * Peak voltage.

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