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DC Servo MOSFET Amplifier
DC Servo MOSFET Amplifier
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Old 15th September 2010, 12:34 AM   #91
glazarou is offline glazarou  Greece
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Apex seems i begin to love this amp ...the corrected clear schematic is this...

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with different R14 values(tried 22k,30k,56k) and different supply voltage, circuit gave 50W-200W on 8ohm with great frequency response....

i try now to use opamp at front-end for smaller and simpliest pcb....
i tried many opamps so far (opa637,tl072....) but only the NE5532 gave a good result...60W/8Ohm
using +-50 supply and 30k(R14) on feedback...
i 'm not an expert on opamps so,any idea which other opamps to try?
the circuit i try is this....

Click the image to open in full size.

is there something that im missing?also the sine is not clear at output...seems to have much distortion...

Click the image to open in full size.

Last edited by glazarou; 15th September 2010 at 12:37 AM.
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Old 15th September 2010, 10:14 AM   #92
apexaudio is offline apexaudio  Serbia
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Your schematic is wrong. This circuit use OP and is simple.
Regards
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Old 15th September 2010, 10:20 AM   #93
apexaudio is offline apexaudio  Serbia
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You can see PCB for this circuit in thread MOSFET Amplifier IRFP240/IRFP9240 post #253.
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Old 15th September 2010, 03:26 PM   #94
glazarou is offline glazarou  Greece
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hmm..wasnt so easy as i though...

similated with no good results...~18W/8ohms
with R12=1k...

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Old 15th September 2010, 03:44 PM   #95
apexaudio is offline apexaudio  Serbia
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You forgot 220R from 22R emiter resistors of BD243/BD244 to gnd.
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Old 15th September 2010, 04:50 PM   #96
glazarou is offline glazarou  Greece
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oops....forgot it.....once more thanks for help...

fixed & worked
i changed values on R14 & R28 for ~110W/8Ohms
Click the image to open in full size.

sine
Click the image to open in full size.


the frequency response wants a fix....and you know i got 110W at 1Khz...
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Old 15th September 2010, 06:49 PM   #97
apexaudio is offline apexaudio  Serbia
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C4 is 1nF not 100pF, and remove zobel R25,C16. Compenzationfor 220R, 22pF missing.

Last edited by apexaudio; 15th September 2010 at 06:53 PM.
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Old 15th September 2010, 07:16 PM   #98
glazarou is offline glazarou  Greece
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no...nothing changed

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Old 15th September 2010, 07:32 PM   #99
apexaudio is offline apexaudio  Serbia
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This frequency response is to wrong to be real. In real life response is ok.
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Last edited by apexaudio; 15th September 2010 at 07:36 PM.
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Old 15th September 2010, 07:53 PM   #100
apexaudio is offline apexaudio  Serbia
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What program you use for simulation?
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