1) think simple and controllable.
Forget transformers and Class D .
Problems must be solved one at a time, without introducing new uncontrolled variables.
As in: if you want to make shaker easy to drive, buy the higher impedance one instead of kludging a transformer in the middle.
Back to the one you have.
2) The main problem is that we don't have the slightest idea as of its impedance curve, and I mean its loaded impedance.
It moving in free air, unloaded, may be interesting but not our main problem today.
Here I suggest a circuit to measure that.
Not the definitive one, of course, but we must do some measuring first or this is just idle talk.
It goes down to DC so if you want to apply , say, a 0.1 Hz squarewave with 50% duty cycle , as in : "5 seconds up, 5 seconds down" to see how far the load flexes, moves or whatever, you can do it.
Try that with a transformer .
This is not a speaker, this is not Audio (although so far specified frequencies lie within the Audible range), this is ElectroMechanical Engineering and it's a shaker driving a load, not a speaker moving air ...... although both devices are "cousins".
This circuit supplies 1A peak with 1V peak input, at any frequency from DC to a few KHz.
You connect the generator at its input, set to 1V Pk, check that you have 0.1V Pk at the 0.1 ohms resistor and them measure voltage across the shaker coil, at any frequency you wish.
The lowest value you will get there is 1 * 0.37= 0.37V Pk ... the highest only God knows (so far ) and you will too, after you measure.
This is a very simple, stripped to the bones measuring circuit, to get data which is not in the datasheet.
After that, you can start with the real design
a) it may oscillate.
The TDA2030 is not designed for gain less than 10X ... but since that depends on the shaker impedance which we absolutely ignore, let's start as is and later compensate, if necessary.
b) start with some +/-8V DC supply, from a 6+6 VAC transformer, a bridge and a couple 4700x16V caps.
We start low (the minimum the chip can use), to minimize dissipation due to horrible impedance matching.
Impedance we still don't know by the way.
This is what I would build in a jiffy to start with preliminary measurements, later a proper design can be made.
Forget transformers and Class D .
Problems must be solved one at a time, without introducing new uncontrolled variables.
As in: if you want to make shaker easy to drive, buy the higher impedance one instead of kludging a transformer in the middle.
Back to the one you have.
2) The main problem is that we don't have the slightest idea as of its impedance curve, and I mean its loaded impedance.
It moving in free air, unloaded, may be interesting but not our main problem today.
Here I suggest a circuit to measure that.
Not the definitive one, of course, but we must do some measuring first or this is just idle talk.
It goes down to DC so if you want to apply , say, a 0.1 Hz squarewave with 50% duty cycle , as in : "5 seconds up, 5 seconds down" to see how far the load flexes, moves or whatever, you can do it.
Try that with a transformer
.This is not a speaker, this is not Audio (although so far specified frequencies lie within the Audible range), this is ElectroMechanical Engineering and it's a shaker driving a load, not a speaker moving air ...... although both devices are "cousins".
This circuit supplies 1A peak with 1V peak input, at any frequency from DC to a few KHz.
You connect the generator at its input, set to 1V Pk, check that you have 0.1V Pk at the 0.1 ohms resistor and them measure voltage across the shaker coil, at any frequency you wish.
The lowest value you will get there is 1 * 0.37= 0.37V Pk ... the highest only God knows (so far
) and you will too, after you measure.An externally hosted image should be here but it was not working when we last tested it.
This is a very simple, stripped to the bones measuring circuit, to get data which is not in the datasheet.
After that, you can start with the real design
a) it may oscillate.
The TDA2030 is not designed for gain less than 10X ... but since that depends on the shaker impedance which we absolutely ignore, let's start as is and later compensate, if necessary.
b) start with some +/-8V DC supply, from a 6+6 VAC transformer, a bridge and a couple 4700x16V caps.
We start low (the minimum the chip can use), to minimize dissipation due to horrible impedance matching.
Impedance we still don't know by the way.
This is what I would build in a jiffy to start with preliminary measurements, later a proper design can be made.
Audio Precision has a patent on using a similar technique to linearize its sig-gen output trafo. The primary winding resistance is cancelled by making the magnitude of the output impedance of the driving amp the same, but negative in sign. However they start out with a nickel cored trafo which has lower distortion than iron. They do achieve better than -100dB distortion though which is highly unlikely to be obtained from any driving chipamp.
Now that's a nice little power op amp. How'd that slip under my radar?
This looks like it was designed for industrial servo systems. I bet it would work great in this application.
Hey! , that one looks good
That said, it can be used with the current drive circuit I suggested for preliminary measurement.
And after operating parameters are measured, also used for the definitive design.
I just posted a video, a little while back, where a guy made a Huge Paralleled Chipamp with 18 LM3886's.
He used it to direct drive his DIY 4 foot by 14mm wide ribbon speaker.
It worked pretty good and I quite was amazed!!
He showed his laptop displaying the peak voltages of about 2V to 3V or so in real time as it was playing .
So, Yes, It can be done !!
This was the First time I had actually seen such a beast and have only read about such things.
I have been obsessed with this sort of technology ever since I have learned that it could be done some 20 years ago!!!!
It would take about 4 to 8 LM3886's depending on how hard you need to drive the thing to get down to a .5ohm level for a load.
FWIW
jer
Here it is !!!
Enjoy!!
http://www.youtube.com/watch?v=hdYfXYKzrT8&list=UUqoEM9AQrfEKxMsVXJyo7-w
He used it to direct drive his DIY 4 foot by 14mm wide ribbon speaker.
It worked pretty good and I quite was amazed!!
He showed his laptop displaying the peak voltages of about 2V to 3V or so in real time as it was playing .
So, Yes, It can be done !!
This was the First time I had actually seen such a beast and have only read about such things.
I have been obsessed with this sort of technology ever since I have learned that it could be done some 20 years ago!!!!
It would take about 4 to 8 LM3886's depending on how hard you need to drive the thing to get down to a .5ohm level for a load.
FWIW
jer
Here it is !!!
Enjoy!!
http://www.youtube.com/watch?v=hdYfXYKzrT8&list=UUqoEM9AQrfEKxMsVXJyo7-w
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It fits the OP's requirements.
What else need be discussed.
That's what I meant. It's like a magic bullet for this application.
OPA549T Texas Instruments | Mouser
Mouser has it in stock.
Check the prices.
Lets say the lowest voltage 10A part: PA51
Digi-Key: $us 145
Apex micro has a fantastic product line.
But is far too rich for my projects.
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