Hello
I am trying to design a circuit to drive an audio exciter (a small 8 ohm driver) at very low frequencies. Rather than use the audio exciter to produce audible sound waves, I am using it in contact with the skin to give a sense of touch. So the frequencies are very low typically 0.5 to 2 Hz. I originally thought that I would use a small audio amplifier but have realised that these are only able to push and pull the driver by coupling the output through a capacitor and at the frequencies I am interested in, this doesn't seem like a good solution since I would need a huge capacitor. So I was hoping to drive the exciter directly from a high power op amp. I am using battery power and so was thinking of creating a dual supply with two Lion batteries. One side of the audio driver would be connected to ground (between the batteries) and the other side would be driven positive and negative depending on the voltage at the input) provided by an arduino. When negative I am naively assuming that the op amp will just sink current from the ground via the driver. There is no sink current in the spec - so I was hoping that the sink and source current ceiling would be the same.
The max current through the driver is about 400mA and I have found a nice cheap op amp (L272) that can go up to 750mA - so I was assuming this might work. Here is my schematic. The input from the arduino is ac coupled and biased so that the op amp sees a true AC input.
I am just wondering if this circuit is likely to work ? Or is there a better way to do this?
Thank you for any advice !
Stephen
I am trying to design a circuit to drive an audio exciter (a small 8 ohm driver) at very low frequencies. Rather than use the audio exciter to produce audible sound waves, I am using it in contact with the skin to give a sense of touch. So the frequencies are very low typically 0.5 to 2 Hz. I originally thought that I would use a small audio amplifier but have realised that these are only able to push and pull the driver by coupling the output through a capacitor and at the frequencies I am interested in, this doesn't seem like a good solution since I would need a huge capacitor. So I was hoping to drive the exciter directly from a high power op amp. I am using battery power and so was thinking of creating a dual supply with two Lion batteries. One side of the audio driver would be connected to ground (between the batteries) and the other side would be driven positive and negative depending on the voltage at the input) provided by an arduino. When negative I am naively assuming that the op amp will just sink current from the ground via the driver. There is no sink current in the spec - so I was hoping that the sink and source current ceiling would be the same.
The max current through the driver is about 400mA and I have found a nice cheap op amp (L272) that can go up to 750mA - so I was assuming this might work. Here is my schematic. The input from the arduino is ac coupled and biased so that the op amp sees a true AC input.
I am just wondering if this circuit is likely to work ? Or is there a better way to do this?
Thank you for any advice !
Stephen
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