What would be the best type of circuit to oscillate a voice coil at 100Hz operating with approximately 45mA. I have a supply of 3-3.5 VDC available. I am trying to vibrate the coil and believe that a square output would be best. I have looked at various circuits with the 555 timer, but are there better more efficient ones?

Thank you very much in advance.

 

What would be the best type of circuit to oscillate a voice coil at 100Hz operating with approximately 45mA. I have a supply of 3-3.5 VDC available. I am trying to vibrate the coil and believe that a square output would be best. I have looked at various circuits with the 555 timer, but are there better more efficient ones?

Thank you very much in advance.

A 555 is a pretty efficient way to go. You might want to resonate the voice coil with a capacitor, which will greatly smooth out the tone. Not sure exactly what your application will be. (A loudspeaker actually has two main resonances...the mechanical one, and the electrical one. There's a great deal of interaction between them. But try putting a 10 uf capacitor across the coil for starters. If you want to get into a great deal of detail on this, I'll show you how to determine the free air resonance frequency of any speaker.

eric