Greetings. I'm currently working on a project that requires recording multiple audible frequencies to the same audio file. Basically I'm recording the tone and monitoring the freq spectrum for freq changes over a long period of time. I'm using a 555 to produce the tone, since its frequency changes as the condition of what I'm monitoring changes. My issue is, when I view the spectrum, I end up w/ all of the harmonics. I am wanting to remove these harmonics so I can use that bandwidth for other tones simultaneously. Therefore I'd be able to monitor several sensors at once... each sensor consisting of the same 555 circuit of course. I realize I could use a notch filter on every oscillator, but I'm wanting to see if there is a different way of filtering the harmonics, or even a way to produce the tones w/out even creating the harmonics. I was considering using an electret mic element coupled w/ a transducer assuming that the harmonics wouldn't be broadcasted to the mic. But I don't know if this will work.
Any thoughts? Any help would be appreciated.
Thanks as always J.Shrum snipped-for-privacy@gmail.com