DC Servo MOSFET Amplifier

[apexaudio]

40mA per output MosFET is quite low.

There is only single pair of mosfets, and 5 pairs of BJTs.

 

[AndrewT]

He asked for the recommended idle bias current. You said 200mA.

Clarify!

 

[apexaudio]

He asked for the recommended idle bias current. You said 200mA.

Clarify!

If you set 200mA bias current, BJTs runs without bias, all bias current is thru MOSFET.

 

[AndrewT]

If you set 200mA bias current, BJTs runs without bias, all bias current is thru MOSFET.

you are confirming that the idle bias is zero.
You must make clear how to set up the operating currents in your ClassB style output stage.

 

[apexaudio]

you are confirming that the idle bias is zero.
You must make clear how to set up the operating currents in your ClassB style output stage.

No BIAS is 200mA, MOSFET are outputs, this is hybrid output stage, at low level only mosfets runs, and BJTs add current at higer power level.

 

[AndrewT]

Ah,
I forgot this is a hybrid. My failing.

But, that shows that the information you gave out could be confusing.

This unusual circuit requires more clarity in the setting up instructions that you will need to provide.
Simply stating bias is 200mA is not enough.

 

[apexaudio]

Ah,
I forgot this is a hybrid. My failing.

But, that shows that the information you gave out could be confusing.

This unusual circuit requires more clarity in the setting up instructions that you will need to provide.
Simply stating bias is 200mA is not enough.

I don't want that people who need clarity build this amp, and ask to many questions. My English is bad, and I can't help diyers without expirience. If someone find any usefull in this circuit...

 

[apexaudio]

Seting bias is simple like in any amp with lateral mosfets, 10R resistors in rail, and adjust with pot (R22, 1k) to get 2V on them.

 

[andrewlebon]

hi apex audio
greetings built your FS 100 PSU want to use it on 75 0 75 dc voltage can you please tell what modifications are required other than supply caps want to use in quasi amp for beginers
thanking you
andrew lebon

 

[nix]

Amplifier for 1R load

hi sir apex,

do you have pcb and component layout with this amp? coz i want to try with this design. Thank you.

regards,
nix

 

[andrewlebon]

diyAudio Member

Join Date: Feb 2008

hi apex audio
greetings built your FS 100 PSU want to use it on 75 0 75 dc voltage can you please tell what modifications are required other than supply caps want to use in quasi amp for beginers
thanking you
andrew lebo

 

[apexaudio]

diyAudio Member

Join Date: Feb 2008

hi apex audio
greetings built your FS 100 PSU want to use it on 75 0 75 dc voltage can you please tell what modifications are required other than supply caps want to use in quasi amp for beginers
thanking you
andrew lebo

Use 10000uF/80V caps, 1k5/5W instead 1k2/5W and add 0R1/5W in parallel to get 0,05R/10W for short circuit protect with 4 pairs outputs.
Regards

 

[apexaudio]

hi sir apex,

do you have pcb and component layout with this amp? coz i want to try with this design. Thank you.

regards,
nix

Use F100 pcb as driver and separate pcb on heatsink for outputs.
Regards

 

[de Ocampo]

F100 MKII

Hi APEXAudio,

Was coolets design uses a different schematic for F100MkII,
F100 schematic in the thread looks different, do you have the schematic for F100MkII?

Is the PSU for F100 will work for a +/-25v rail, I have here an amp with only +/-36vdc rail, I wish to use your PSU design for F100.

This post was rather late, just noticed in my copy though..


Thanks & Regards!

 

[apexaudio]

Hi APEXAudio,

Was coolets design uses a different schematic for F100MkII,
F100 schematic in the thread looks different, do you have the schematic for F100MkII?

Is the PSU for F100 will work for a +/-25v rail, I have here an amp with only +/-36vdc rail, I wish to use your PSU design for F100.

This post was rather late, just noticed in my copy though..


Thanks & Regards!

There is several different version of F100, and you can find schematics in the thread just notify post number.
PSU can work with +/-36vdc just change resistor in series with relay to get 24vdc on coil, or use 12v relay.
Regards

 

[de Ocampo]

post #141, horizontal lay there was a couple of IRF's 9610/610 is this correct?


Thanks

 

[apexaudio]

post #141, horizontal lay there was a couple of IRF's 9610/610 is this correct?


Thanks

This is version upgrade with mosfet drivers, schematic in post #70, look at post #121 also.
Regards

 

[de Ocampo]

got it!!



Thanks & Regards

 

[nix]

Use F100 pcb as driver and separate pcb on heatsink for outputs.
Regards

ok thank you sir apex..

regards,
nix

 

[apexaudio]

PSU with Protect... pictures from local forum.