So...I am working on this ir heart rate monitor project...found it on the internet!! Its a really simple circuit...an ir emitter and a detector pair is used as a sensor...which is touched to your skin...it shines light up your skin and then reflected light is detected by the detector..this signal is then fed into an lm386 which amplifies the signal which is fed into an analog pin of an arduino or any micro controller...There's a code running on this microcontroller which sends this data via serial communication to the pc..there's a processing app on pc which reads this data and visualizes it (well it actually draws a straight line on the screen if you know what I mean) so..I was thinking if I could send that signal though my microphone port on my pc...then write a app that would visualize it!! I mean..what my lm386 generates is just a signal right?? (I know Lm386 is not ideal for such projects...it's noisy...I had Lm386 laying around so i used it..the signal was really noisy but then i blasted that amp with caps..now its presentable..i will replace it!! ) Similar to what my mic generates...if it is possible..it would fun ...i mean i could plug that into my android devices and write and app for it!! I know that my soundcard won't respond to such low frequency signal!! How do i convert that signal to something that my soundcard will detect??