Recent content by windell747

thanks, windell

is there any freeware that you may know of that I can use to simulate the performance of my filtering circuit? I don't have the radio with me as I'm on vacation from the lab so I don't have a chance to do some testing of the audio quality of sending a square wave into the mic input of the radio...

Thanks VE1BLL. I was once told about the passband filter within the radio. I wasn't sure if I should just assume that this already exists in the radio. The radio is the VX3R. Is there any way I can look this up for sure? Thanks, windell

would it be better if I put the capacitor at the end of the butterworth filter? or how about at the output of the opamp so that there is more current flowing?

Thanks, I really appreciate it!

I guess i was reading that for active filters the number of opamps usually identify the amount of poles in the filter. And for a single pole filter TI's filter pro only comes up with a single op amp so I assumed that a salleen filter with a single opamp was a single pole filter. Of course I...

yeah im sorry, I just want to try to follow the books as much as possible because this circuit is being reviewed by other members on my team and I need to make sure that I can analyze everything and not wing anything. I really like your 2 pole butterworth filter. To filter out the DC component...

I apologize for making a new thread I thought it was a little bit different of an idea, but after thinking about it, it is pretty much the same. So I guess to get the unattenuated sine wave at 1020Hz and to filter out the DC component, it would probably be best for me to go with an active...

Thanks! to make ease of calculating the correct values I was thinking about using a 2 pole lowpass butterworth filter. I guess TI's filter pro can come up with convinient component values for you. Do you see any disadvantages to this? You will see that I put up a new post asking about this. I...

I'm filtering a 1020Hz 3.3V squarewave from a microprosessor using a 2 pole low pass butterworth filter. Thanks to TI for their filter pro! I would like the output frequency of filter to be a 1020Hz sine wave. I realize that if I select the cutoff frequency at 1020Hz that my sine wave will be...

I'll be putting a noninverting amplifier at the end of the double stage filter do make use of the high output impedance of the opamp. Do you think that that will solve the parasitic effects? Also I think you 1000k value isn't correct if a 0.47uF capacitor is used. Are there any advantages to...

This is wonderful! This might seem a little dumb, but is there a way I can see that there is no components lower than the fundamental frequency of the square wave? I see the that first couple terms of the fourier transform of the square waves is .... ((4k)/pi)*(sinx+0.33sin3x+0.20sin5x...)...

Should I not pass the single through a band pass or is a low pass filter enough? The frequency of interest is 1020Hz or about 1kHz.

Thank you for the reply! In using your suggestion, how to I filter out the higher harmonics? Could you direct me to a resource showing me what the cutoff frequencies are for your circuit? Also...what is the gain after the cutoff frequency? thanks, windell

5Hz sinusoid preferably... could also use a square waveform, but not as preferable. The current requirement I know is small (mA range), but I still need to calculate it.