DC Servo MOSFET Amplifier

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#81
RE Replacements for IRF240/IRF9240

apexaudio said:
IRF640/IRF9640 or IRF540/IRF9540 (with +/-45V DC max rail voltage) can be used.
Click to expand...

Hi Apex,

I found IRF540/IRF9540 fets. I have a +/-49V DC transformer with me. Can I use this transformer or is +/-45V the absolute max voltage for this amp with this fets. If so I will then continue my search for the proper fets. Any mods I can do to use this fets with my voltage?

Regards,
Macd🙂🙂🙂
 
#82
macd said:
Hi Apex,

I found IRF540/IRF9540 fets. I have a +/-49V DC transformer with me. Can I use this transformer or is +/-45V the absolute max voltage for this amp with this fets. If so I will then continue my search for the proper fets. Any mods I can do to use this fets with my voltage?

Regards,
Macd🙂🙂🙂
Click to expand...

What is AC voltage on transformer? You can use IRF540/IRF9540 with +/-49V DC rail voltage for usual home listening.
Regards
 
#84
+-49Vdc from a 35+35Vac transformer seems a bit low.

Is the transformer 230:35+35Vac?
Is your supply 220Vac when you measure the rectified DC voltage?
Are you using a single bridge rectifier with a CT transformer, or are you using dual bridge rectifiers with dual secondaries?
 
#85
RE Replacements for IRF240/IRF9240

AndrewT said:
+-49Vdc from a 35+35Vac transformer seems a bit low.

Is the transformer 230:35+35Vac?
Is your supply 220Vac when you measure the rectified DC voltage?
Are you using a single bridge rectifier with a CT transformer, or are you using dual bridge rectifiers with dual secondaries?
Click to expand...

Yes, the transformer is rated at 220:35+35Vac. I am using a single bridge rectifier with my transformer. Only one secondary. I have measured my DC volts on output of transformer. +/-49V DC.

Macd
 
#87
Stcboy's F100
 

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#90
Forum member do simulation of new DC Servo Mosfet Amp, after correct some mistakes on schematic. I must design PCB for this Amp or someone else do that🙂
 

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#91
Apex seems i begin to love this amp 😀...the corrected clear schematic is this...

An externally hosted image should be here but it was not working when we last tested it.


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....

An externally hosted image should be here but it was not working when we last tested it.


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

An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
#96
oops....forgot it.....once more thanks for help...

fixed & worked
i changed values on R14 & R28 for ~110W/8Ohms
An externally hosted image should be here but it was not working when we last tested it.


sine
An externally hosted image should be here but it was not working when we last tested it.



the frequency response wants a fix....and you know i got 110W at 1Khz...
An externally hosted image should be here but it was not working when we last tested it.
 
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