Opamp challenge - Page 12 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Closed Thread
 
Thread Tools Search this Thread
Old 24th January 2013, 05:19 PM   #111
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by Mooly View Post
OK thanks

I guess we're just going to have to see what you come up with. Extending the LF response by reconfiguring the circuit is easy of course... and does what you ask... but I guess that's not what your getting at.

The first simulation here wouldn't work in practice using real parts (although it does work in spice)

The second would work of course but its totally standard and can't be what you are getting at. It does have the added bonus though of decoupling the opamp rails though, which is is a "huge" benefit.

So I guess its over to you to show what you have come up with

(we are all intrigued)
I'm getting confused sorry

Last edited by FdW; 24th January 2013 at 05:22 PM.
 
Old 24th January 2013, 05:24 PM   #112
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by magdrop View Post
Do you know why Mooly's example makes the .1uf cap look like a 10uf? I'd really like some help with that.
Where was that posted? Again confused: You refer to the 100nF used as the output capacitor (that will limit low frequency output voltage swing severely (I think)).

Last edited by FdW; 24th January 2013 at 05:26 PM.
 
Old 24th January 2013, 06:56 PM   #113
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by magdrop View Post
I think everyone understood your position the first time you posted it. The 37th time doesn't add a whole lot.

Do you know why Mooly's example makes the .1uf cap look like a 10uf? I'd really like some help with that.
Do you mean this one, post #31
Opamp challenge

The 0.1 is now included in the feedback loop. Our point of interest is across the 10k and so the feedback keeps this point correct. If you look at the output
of the opamp rather than the notional output terminal of the circuit then the opamp output rises with decreasing frequency to counter the rise in Xc of the cap. The downside is that the circuit will clip easily at low frequency because the output of the opamp has to be so large.

Here's the output of the opamp rather than at the other side of the cap.
Attached Images
File Type: jpg Capture2.JPG (137.0 KB, 139 views)
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
 
Old 24th January 2013, 10:34 PM   #114
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Quote:
Originally Posted by magdrop View Post
I think everyone understood your position the first time
you posted it. The 37th time doesn't add a whole lot.
Hi,

Such a childish comment adds nothing.

Address the points in the post or say nothing.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 24th January 2013 at 10:37 PM.
 
Old 25th January 2013, 03:26 AM   #115
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Quote:
Originally Posted by Mooly View Post
Post #90 tells us that the 10k connects between pin 6 and zero volts which means that the output voltage must be measured on pin 6 to meet the requirement of "the output voltage is developed across the 10k"

No nearer
When connected beween V(out) and Gnd, then it serves no purpose.
And who says it's connected between Vout and Gnd?
 
Old 25th January 2013, 07:29 AM   #116
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by JMFahey View Post
And who says it's connected between Vout and Gnd?
Post #90

Quote:
Originally Posted by diegomj1973 View Post
If it helps: the 10K resistor is connected directly between pin 6 and 0 volts (in both variants: the common and modified). It may be another value, too: to make it more generic.

Tested with TL071, TL081CP, LM741.

It works in real conditions and simulations.

I had uploaded a video on YouTube that showed a better response at low frequencies. However, I had to delete when I realized the possibilities this could offer myself.

regards
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
 
Old 25th January 2013, 08:11 AM   #117
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Not necessarily the same
 
Old 25th January 2013, 08:41 AM   #118
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Agreed ... that is why I asked earlier if two identical circuits could be made (as in left and right) and fed from a normal source (such as a CD player with common grounds for the players L and R outputs and with no interaction)
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
 
Old 25th January 2013, 10:55 PM   #119
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

I currently amuse myself occasionally by buying toy kits that on the
the box state 3+ (years old), that is true in terms of playing with the
parts, but the real challenge is to use every single part to look like
toy illustrated but without enough instructions / illustrations /
information to be able to do that, and certainly on purpose.

That is the parent bit I guess, and TBH I genuinely assume it
can be done, and if I can't work it out, I'm missing something.

So if some take the same attitude to this "challenge" fair enough.

But I don't, I do know my stuff, and it seems most taken in don't.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 25th January 2013 at 11:12 PM.
 
Old 26th January 2013, 12:15 AM   #120
diyAudio Member
 
Join Date: Jun 2011
So, is there a closure date on this challenge, or can we expect it to go on for ever without the OP's solution ever getting seen?

I certainly wouldn't offer a contribution without some suggestion that I wasn't just *issing in the wind. In fact, I think anyone with a shred of integrity posting such a challenge should have lodged the solution in a sealed envelope with a third party with instructions to open it on a specified date, or earlier if the solution was found, and that anybody taking it up without such a safeguard is misguided. Otherwise, who knows if a solution exists? And even then, it's just a sealed envelope, it could be empty.

I wouldn't have been as outspoken as sreten for reasons I'll leave you to guess, but I'm damned glad somebody has been. There's something about this thread that doesn't really respect the members, whether or not some people are insensitive to it.

Last edited by counter culture; 26th January 2013 at 12:20 AM.
 

Closed Thread


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Here's a challenge.... Meshuganah Solid State 42 16th November 2011 02:59 AM
Here is a Challenge latala Solid State 41 12th May 2011 02:13 AM
Single supply opamp - unequal rail voltage and opamp selection Hans L Parts 8 19th February 2006 03:15 PM
a challenge --or I need help lawrence99 Car Audio 0 9th March 2005 05:44 AM
The challenge ! thylantyr Solid State 51 24th July 2003 09:41 PM


New To Site? Need Help?

All times are GMT. The time now is 10:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2