Hello,
Here are some pages that will explain the integrator circuit:
http://www.radio-electronics.com/info/circuits/opamp-circuits/operational-amplifier-integrator.php
http://www.electronicshub.org/operational-amplifier-as-integrator/
Bertus
I've seen them, doesn't mention how to do it to a biased signal. And what's the advantage in using this instead of a simple low pass filter.Hello,
Here are some pages that will explain the integrator circuit:
http://www.radio-electronics.com/info/circuits/opamp-circuits/operational-amplifier-integrator.php
http://www.electronicshub.org/operational-amplifier-as-integrator/
Bertus
It won't be cut off if you power the op amp from plus and minus supplies rather than merely + and ground.I only found this schematic, I didn't find any 'real' scenario since the negative part would be cut off.
A negative supply, is all.What should I add do this so that I can integrate a biased square wave?
With a low pass filter, the magnitude of the filter's response levels off below a certain frequency (the "cutoff" frequency) and remains constant from there all the way down to DC. An integrator has no cutoff frequency and its response continues to increase with decreasing frequency. In a perfect integrator, this continues down to DC, where the response becomes infinite; however, in practice every op amp has a maximum DC gain, and this limits the gain of any practical integrator as the frequency approaches zero.By the way, what's the difference between an integrator and a low pass filter?
I would need a dual supply to do that, it's not pratical since I would use later on a 9V transformer.It won't be cut off if you power the op amp from plus and minus supplies rather than merely + and ground.
A negative supply, is all.
With a low pass filter, the magnitude of the filter's response levels off below a certain frequency (the "cutoff" frequency) and remains constant from there all the way down to DC. An integrator has no cutoff frequency and its response continues to increase with decreasing frequency. In a perfect integrator, this continues down to DC, where the response becomes infinite; however, in practice every op amp has a maximum DC gain, and this limits the gain of any practical integrator as the frequency approaches zero.
In that case you will have to "lift up" the entire operating range of the integrator by connecting the (+) input of the op amp to some positive reference voltage (for example, Vsupply/2 from a resistive voltage divider) and considering that reference voltage as your "virtual ground."I would need a dual supply to do that, it's not pratical since I would use later on a 9V transformer.
I have no idea what you mean by the above. The difference between a low pass filter and an integrator is exactly as I described in post #5 above.So a low pass filter would have differente results for 100 Hz and 300 Hz (just an example), and the integrator would have the same results, but both with amplitude differences (depending on the frequencies).
For example, using a three stage low pass filter for a 10 hz square wave, I get this:In that case you will have to "lift up" the entire operating range of the integrator by connecting the (+) input of the op amp to some positive reference voltage (for example, Vsupply/2 from a resistive voltage divider) and considering that reference voltage as your "virtual ground."
I have no idea what you mean by the above. The difference between a low pass filter and an integrator is exactly as I described in post #5 above.
That depends entirely on the filter's cutoff frequency, which you haven't specified; if it's less than or equal to the frequency of your square wave, you can get a reasonable approximation of a sine wave on the filter's output. Also, the more filter sections you cascade, the better job the filter will do of attenuating the square wave's harmonics and thereby leaving you with a clean(er) sine wave.For example, using a three stage low pass filter for a 10 hz square wave, I get this:
For 40 Hz, I get this:
I'm asking if for 10 Hz I would get a good sine wave like for 40 Hz using an integrator.
I have a square wave that has 9V or 0V.Hello,
Assuming the input signal is a squarewave of about the same amplitude as the powersupply, you could use the following circuit:
View attachment 132125
Bertus
I'm using three filter sections, the volume is low and it sounds good, but when I amplify it, the lower frequencies get fuzzy. So I want to try something that has better filtering across the frequencies (same for all, not having some frequencies fuzzier then others).That depends entirely on the filter's cutoff frequency, which you haven't specified; if it's less than or equal to the frequency of your square wave, you can get a reasonable approximation of a sine wave on the filter's output. Also, the more filter sections you cascade, the better job the filter will do of attenuating the square wave's harmonics and thereby leaving you with a clean(er) sine wave.
Hello,
What opamp are you using?
What offset voltage did you create?
By playing with the voltage divider on the + input, you should get a symetric output signal, assuming the input signal has a 50/50 dutycycle.
Bertus
by Jake Hertz
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