I've been playing around with an IC named MSGEQ7 which returns the amplitude of seven different frequency bands. To be able to utilize it, I use arduino.
Now I want to make the circuit permanent but I realised that I really don't need to use this IC with an Arduino, instead I can build separate band-pass filters to get the amplitude of the desired frequency band.
So, what I want to do is designing a band-pass filter with a varying capacitor or resistor so that I can shift the center frequency of the band-pass filter. But I really don't need the amplitude of the frequency instead I want to get HIGH or LOW if there is this frequency in the given signal.
I am planning to connect the output of each filter to base of an NPN transistor to drive some LEDs.
So, all in all I need help for designing the band-pass filter. I want to use op-amp to make it easier (I think it makes it easier, right ?) But I don't know much about it. Googled it but could not find a proper design, especially with a varying parameter to be able to change the middle frequency.
Appreciate if you guide me.
Now I want to make the circuit permanent but I realised that I really don't need to use this IC with an Arduino, instead I can build separate band-pass filters to get the amplitude of the desired frequency band.
So, what I want to do is designing a band-pass filter with a varying capacitor or resistor so that I can shift the center frequency of the band-pass filter. But I really don't need the amplitude of the frequency instead I want to get HIGH or LOW if there is this frequency in the given signal.
I am planning to connect the output of each filter to base of an NPN transistor to drive some LEDs.
So, all in all I need help for designing the band-pass filter. I want to use op-amp to make it easier (I think it makes it easier, right ?) But I don't know much about it. Googled it but could not find a proper design, especially with a varying parameter to be able to change the middle frequency.
Appreciate if you guide me.