DC Servo MOSFET Amplifier

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
R

rsavas

Member
Joined 2012
As always nice build Terry, cheers to you but I have a question about the design itself.
What I do not understand with this design, is why the, so called, "evil" feedback cap "C6" is being used? I thought the whole idea of using a DC servo-controlled design, is to eliminate the evil ecap in the FB path, that is for controlling the DC offset and allow for DC gain? Unless the servo can not compensate for the amount of DC offset without using C6, which brings the whole design topology into question.
 
prasi

prasi

Member
Joined 2014
sites.google.com/site/analogdesign1234/
Paid Member
Mark Tillotson said:
I looked at the board layout and there is a distinct lack of star grounding, so that the high currents from the rail decoupling capacitors get injected into small signal ground - that's probably enough to risk oscillation.

This is made worse by the ground trace being pretty thin and split two-ways, rather than flood-filled plane - most of the top side is unused and could be used for decent ground.
Click to expand...

Dear Mark, this pcb ( one of my first) was done with some inputs, read back. input ground is separate.
This is an old styled DIY pcb with no provision for top layer but for jumpers:). Anyone with copper clad and few parts in his bin can build this.

regards
prasi
 
prasi

prasi

Member
Joined 2014
sites.google.com/site/analogdesign1234/
Paid Member
rsavas said:
As always nice build Terry, cheers to you but I have a question about the design itself.
What I do not understand with this design, is why the, so called, "evil" feedback cap "C6" is being used? I thought the whole idea of using a DC servo-controlled design, is to eliminate the evil ecap in the FB path, that is for controlling the DC offset and allow for DC gain? Unless the servo can not compensate for the amount of DC offset without using C6, which brings the whole design topology into question.
Click to expand...

There is no "C6 evil feedback cap" in the design that Terry built. The design is according to following sch.
DC Servo MOSFET Amplifier
 
still4given

still4given

Member
Joined 2004
prasi said:
Nice build Terry,
I am sure there is someway to configure clip leds, Mr. Mile can tell us.
regards
prasi

A side note: you have created a great shortfall of diamond plates which could have been used elsewhere to support infrastructure development by Governments!:D;)
Click to expand...

Hi Prasi,

The PSU I used is the original FX100 PSU. It has clip LED's built into the circuit. I tried to use them but every time I drove the amp hard enough to make it clip it blew the LED. I thought I had wired it wrong initially but after 4 LED's I realized it is hitting them too hard.
 

Attachments

  • FX100 PSU.png
    FX100 PSU.png
    670.9 KB · Views: 398
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom