Hey,

I'm working on a project trying to produce physical vibrations using an analog signal from "music" files in the low 50-500 Hz range. I'm looking at 4-10 actuators to produce vibrations for a particular range of frequencies (ex one actuator for 50-100 Hz, another for 100-200 Hz, etc).

My current attempt has been to take the signal directly from an aux audio cable, amplify it, filter it using a 4th order filters and then present it to voice coil exciters, which actually vibrate at the frequency of the input signal.

My knowledge of circuit design is limited and I simply copied an online 4th order circuit to create a low pass 300 Hz filter. My first question is, is it possible to design bandpass filters with a width of about 50 Hz or less? I've been told otherwise but I wanted to ask a larger audience.

Also, I'm trying to steer away from circuits and implement something in software so I can apply some more complex algorithms for the filtering. The voice coil exciters take in an analog "AC" signal, but I think I also have the option of using AC vibrating motors. I think the speed of an AC motor is proportional to the frequency of the signal so an AC motor should capture the information present in a band of frequencies as input. What can I use to output a bunch of analog signals carrying different bands of frequencies (analyzed and separated on a phone/computer/whatever) that would be used as input to these vibrating actuators?

Thanks for any help!

 

My first question is, is it possible to design bandpass filters with a width of about 50 Hz or less?

It certainly is! I used to work for a company that made filters that chopped the telephone audio band into 24 separate audio channels. Each band was about 100Hz wide, flat topped, and did not interfere with the one next to it. They used 8-pole passive Chebyshev filters using ferrite cores and precision capacitors.

Now days I would look at switched capacitor filters. In fact, could you simply rely on a mechanical resonance in the things you are going to vibrate?

Edit: Google found this http://cds.linear.com/docs/en/application-note/an27af.pdf