It's a commendable effort that you're willing to share your PCB designs free of charge but I must say it would have been much better if the PCBs had been tested prior to publication. That said, I would like to draw your attention to a serious (you might say burning
) flaw in your current design. Namely, the emitter of the transistor Q5 should be connected to the minus power supply, not the ground, which also goes for the capacitor C1.
As regards the high-power version, the output transistors are too close together and unless there's some forced cooling solution implemented, you might get high smoke levels but certainly not much power.
Regards,
Milan
) flaw in your current design. Namely, the emitter of the transistor Q5 should be connected to the minus power supply, not the ground, which also goes for the capacitor C1. As regards the high-power version, the output transistors are too close together and unless there's some forced cooling solution implemented, you might get high smoke levels but certainly not much power.
Regards,
Milan
Hi Boraomega,
I have couple of questions regarding your second schematic I would like to now more about of curiosity.
1: Why is the Zobel on "the other side" of output coil L1?
2: What is your intention with R14 and why is it not connected before L1?
3: Why is C2 connected to a resistor divider between Q6 & Q7 instead of connecting to just one side, or use double capacitor setup to both side?
4: Would not base stoppers be good to use with Q8 & Q9?
5: The copper trace on PCB between R5 & Gate of Q7 is going underneath output coil L1, shouldn't it be better to redraw that part to avoid eventual coupling leading in worst case to oscillation?
Cheers Michael
I have couple of questions regarding your second schematic I would like to now more about of curiosity.
1: Why is the Zobel on "the other side" of output coil L1?
2: What is your intention with R14 and why is it not connected before L1?
3: Why is C2 connected to a resistor divider between Q6 & Q7 instead of connecting to just one side, or use double capacitor setup to both side?
4: Would not base stoppers be good to use with Q8 & Q9?
5: The copper trace on PCB between R5 & Gate of Q7 is going underneath output coil L1, shouldn't it be better to redraw that part to avoid eventual coupling leading in worst case to oscillation?
Cheers Michael
Thank you MOAMP for pointing to that MORE than serious mistake. I can't explain how I overlooked that?!
It will be corrected promptly!
Regarding publishing PCB's designs prior to even initial testing, you are generally more than right! The only fact I can eventually use as my excuse is that I already stated clearly that I haven't built and tested that schematic and PCB up to this moment, hence, publishing PCB design proposal, I presume, shouldn't be taken by anyone as a "blanco" invitation to build it as a proven and tested design! Frankly, I rarely make mistakes in PCB designs but things happen once in a while... as everyone can see.
My apologize to everyone! Corrected design will be posted tonight! At least, I own that much to all of you.
It will be corrected promptly!
Regarding publishing PCB's designs prior to even initial testing, you are generally more than right! The only fact I can eventually use as my excuse is that I already stated clearly that I haven't built and tested that schematic and PCB up to this moment, hence, publishing PCB design proposal, I presume, shouldn't be taken by anyone as a "blanco" invitation to build it as a proven and tested design! Frankly, I rarely make mistakes in PCB designs but things happen once in a while... as everyone can see.
My apologize to everyone! Corrected design will be posted tonight! At least, I own that much to all of you.
boraomega said:
Bora,
maybe this time it happend twice, but I'm glad you at least payed attention to point number 5 in my previous post in your latest PCB layout, my "curiosity" for this time is very well satisfied!
Cheers Michael
PS: I notice now that your schematic is similar as to the posted one in post #1, I have read this thread before but totally forgotten the similarity between your schematics and thought your schematic was a new proposal by You, pardon on my part moisue!
Ultima Thule said:
Bora,
maybe this time it happend twice, but I'm glad you at least payed attention to point number 5 in my previous post in your latest PCB layout, my "curiosity" for this time is very well satisfied!
Michael,
I certainly paid attention not only to point #5 but to all of them... otherwise that could be seen as a kind of disrespect of a fellow member and that is something that my education and culture won't allow me to do! I am still not convinced about possible negative influence you are worried about, but being already in a process of modification, that was just a few more minutes to make even you happy!
To my opinion it certainly is, not only of LM3886 but also of any GC amp, and by all means. On the other hand, it is more complicated to build but well worth that effort.
Well, for DIY enthusiast designs are rarely "final". Many, according to author's words, did original DOGC but I don't think that anyone managed to test this last modification-proposal yet, including me! I believe to have a chance to test it soon ( duties and time permit).
Well, for DIY enthusiast designs are rarely "final". Many, according to author's words, did original DOGC but I don't think that anyone managed to test this last modification-proposal yet, including me! I believe to have a chance to test it soon ( duties and time permit).
-_nando-_ said:
First one is the version with complementary differential pair.
Second is with feed forward error correction input, and that OP-amp is DC-servo system to keep zero DC on the output. It is not part of the feedback.
As I stated and highlighted before, I haven't built and tested ANY of those ideas yet, and it would be very incorrect and irresponsible from me to judge now will any of them work and how! I believe they WILL!
Let it be said once forever: posting of one schematic should not necessary be taken as "blanco" invitation for anyone to go directly and build it!!!
It seems that you missed my corrected PCB's on page 25!?
I am very sorry if my attempt to contribute caused confusion! Original widowsmaker's schematic should still be there where he posted it and it is full working project according to his statement and confirmations from several other members. I just attempted to introduce some further thinking and possible improvements...