Audio signal to control voltage across electromagnet

[Jamd]

Hi,
I'm a total newbie, so I have a project where I want to manipulate some ferrofluid with an electromagnet using an audio input (from say an iPhone). My initial thoughts was to have say 3 band passes corresponding to 3 electromagnets so you can see the individual elements of the song (such as bass ext).

I was hoping you guys could point me in the right direction in what to read up on how I can get this project rolling.

Like I said total newbie, had some experience with circuits from A level physics but thats about it!!

Many Thanks!
James

 

[Laplace]

What does your ferrofluid display look like? How are the electromagnets arranged around the blob of ferrofluid? Do you expect to turn the electromagnets ON/OFF as with a switch, or driven by ramped currents from a linear amplifier? If the electromagnets were to be pulsed, what is the minimum pulse duration needed to produce a ferrofluid response? What is the maximum square wave frequency before the ferrofluid shows no visual response? Will the electromagnets be unipolar or bipolar? I believe you need to know the essential electrical characteristics of the waveform driving the electromagnets before addressing the signal processing of the audio signal. The signal processing itself may take two possible routes: analog or digital. Analog signal processing would require designing with active filters, envelope detectors, op-amp level shifters, and possibly automatic gain control (AGC). Digital signal processing would require designing with a microcontroller, audio signal conditioning & AGC, analog-to-digital conversion, fast Fourier transform (FFT), and software for driving the electromagnets.