Hi,
I was hoping someone could outline the dimensions of my ignorance. I'm a physics student hoping to start a PhD this year and need to get myself to a reasonable standard with analogue electronics. I've set myself a project which has shown me how little practical electronics I know. Class D amp, what a mistake. Always biting off more than I can chew. At the minute I'm just scraping together the low side using op-amps. I understand the theory of class D operation and perhaps the schematic will be obvious to the more experienced. Its just square-wave > triangular-wave > PWM signal. Im just using a test sinoidal signal on the non-inverting input of the final op-amp. This is in ISIS Proteus btw.
Though I have had some nice looking signals, I think Im missing some of the basics. Im constantly dancing a fine line with non-convergence, eg the triangular signal out of the 2nd op-amp was non-symmetric (slightly lifted w.r.t 0v) so I added R7 to pull it down slightly. This works fine until the resistor reaches 33K then bang, non-convergence error. I have the feeling that Im missing the basics. Ive spent days tinkering and dont seem to be getting anywhere. I understand all the components, its the artistry Im lacking. For now my hope is to produce a reasonable low end stage (input signal to PWM signal for driver stage).
If someone could cast their eyes over this schematic and list the mistakes it would be greatly appreciated. That is if you can stop yourself laughing. Any contributions will be appreciated. I know there are ungrounded pins on the op-amps but this makes no difference in my case. Im going to keep working on this over the next few months and try to build this for a cheap subwoofer I have. I really want to order an oscilloscope and bubble etcher, etc but I think for now It would be jumping the gun. Many thanks
I was hoping someone could outline the dimensions of my ignorance. I'm a physics student hoping to start a PhD this year and need to get myself to a reasonable standard with analogue electronics. I've set myself a project which has shown me how little practical electronics I know. Class D amp, what a mistake. Always biting off more than I can chew. At the minute I'm just scraping together the low side using op-amps. I understand the theory of class D operation and perhaps the schematic will be obvious to the more experienced. Its just square-wave > triangular-wave > PWM signal. Im just using a test sinoidal signal on the non-inverting input of the final op-amp. This is in ISIS Proteus btw.
Though I have had some nice looking signals, I think Im missing some of the basics. Im constantly dancing a fine line with non-convergence, eg the triangular signal out of the 2nd op-amp was non-symmetric (slightly lifted w.r.t 0v) so I added R7 to pull it down slightly. This works fine until the resistor reaches 33K then bang, non-convergence error. I have the feeling that Im missing the basics. Ive spent days tinkering and dont seem to be getting anywhere. I understand all the components, its the artistry Im lacking. For now my hope is to produce a reasonable low end stage (input signal to PWM signal for driver stage).
If someone could cast their eyes over this schematic and list the mistakes it would be greatly appreciated. That is if you can stop yourself laughing. Any contributions will be appreciated. I know there are ungrounded pins on the op-amps but this makes no difference in my case. Im going to keep working on this over the next few months and try to build this for a cheap subwoofer I have. I really want to order an oscilloscope and bubble etcher, etc but I think for now It would be jumping the gun. Many thanks
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