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Old 15th January 2013, 08:07 PM   #21
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JMFahey:

The circuit presented by you does not seem in the least to mine.

Also, if you take the trouble to simulate or measure will notice that this circuit does not meet even close to what I can get with my design.

Believe me, I understand you perfectly in the fact that you may be wary of something new.

The blue curve corresponds to what you have kindly uploaded.

Click the image to open in full size.


regards
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Old 15th January 2013, 09:54 PM   #22
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I used the 741 simply to represent an audio amplifier. But you can extend the application to any similar topology (TL071, TL081, etc or even discrete, like the one I'm using). This can be for small signal or power, too.

Laboratory measurements were made with a simple and inexpensive TL081CP.

I know I'm risking a lot in a forum as prestigious as this. And was not the only one in which I presented this challenge. This is my choice for very personal things (which may be irrelevant to the forum, but it is very important to me).

With my greatest respect
 
Old 16th January 2013, 07:11 AM   #23
Mooly is offline Mooly  United Kingdom
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I'm intrigued by what you feel you have come up with. I haven't been able to replicate all you claim in particular keeping the voltage gain at around +3.9

By AC coupling the output via the 10 uf you can then use the 10K as a ground reference.......

Have you tested your circuit with non sinusoidal waveforms and deemed it acceptable ?
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Old 16th January 2013, 06:38 PM   #24
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Why is it prohibited to skip components? Wouldn't the possibility to achieve a similar result with less components be an inprovement?

If you can live with inverted phase, you can tidy up the following schematic later. I.e. skip the 100 n cap, use 2,4 k instead of 2 x 1,2 k, 9,31 k or 9,53 k instead of 2 x 4,7 k.

Click the image to open in full size.
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Old 16th January 2013, 06:54 PM   #25
TNT is offline TNT  Sweden
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Prior art killed the cat?

/
 
Old 16th January 2013, 07:00 PM   #26
Mooly is offline Mooly  United Kingdom
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I came up with this as per original requirements although I suspect it isn't what he is after... and its just a bit of fun

AC coupled input, Yes
Similar HF response, Yes
Voltage gain of 3.92, Yes
Similar input impedance, Yes
Output developed across the 10K, Yes
Same components used, Yes. All the components in the original are used.
No real offset issue, Yes. The 741 isn't perfect here anyway.
Non inverting of overall phase, Yes
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Old 16th January 2013, 07:44 PM   #27
GoatGuy is offline GoatGuy  United States
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Quote:
Originally Posted by pacificblue View Post
Why is it prohibited to skip components? Wouldn't the possibility to achieve a similar result with less components be an inprovement?

If you can live with inverted phase, you can tidy up the following schematic later. I.e. skip the 100 n cap, use 2,4 k instead of 2 x 1,2 k, 9,31 k or 9,53 k instead of 2 x 4,7 k.
I think the poster (original) is suffering from delusions and is further insufferably pretentious. A "design" without a "purpose", or with a "secret purpose", and an ill-defined "challenge" ... is delusional and pretentious.

"Power - makes others strive to want something that is kept unachievable" - some wag in 1949.

GoatGuy
 
Old 17th January 2013, 12:56 AM   #28
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Pacificblue:

Close, but suffers three important things:

1) The magnitude, while not as is (it is very close), but the phase is inverted. This could be a minor problem but ...

2) The offset problems have not been considered. This stage can cause problems, if the gain becomes important (to make it more generic).

3) There is an improvement that is not served by that configuration, but I can not disclose yet, because it would give guidelines to find the answer.

The blue curve corresponds to what you have kindly uploaded.

regards

PD: I did not say I was forbidden to skip components.

Click the image to open in full size.
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Last edited by diegomj1973; 17th January 2013 at 01:07 AM.
 
Old 17th January 2013, 11:41 AM   #29
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by diegomj1973 View Post
To accomplish this, one has to use the same components shown in Scheme A (referring to quantity, type and value). Not allowed to remove or add components as those shown in Scheme A (you must use the same components, to achieve the objective of this challenge).
Quote:
Originally Posted by diegomj1973 View Post
Pacificblue:

PD: I did not say I was forbidden to skip components.
Please clarify In the first post you say all components must be used (not allowed to remove...) and the later post implies you can skip using some parts.
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Old 17th January 2013, 04:01 PM   #30
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Quote:
Originally Posted by Mooly View Post
Please clarify In the first post you say all components must be used (not allowed to remove...) and the later post implies you can skip using some parts.
Remove: use fewer components that have been shown. Example: if the original scheme employs 8 => implies having used less than 8.
Add: use more components that have been shown. Example: if the original scheme employs 8 => implies having employed more than 8.

There are no restrictions on the order of connection between components. There is complete freedom to connect as you wish.

PD: In the scheme proposed by Pacificblue the input impedance of the circuit is not around 5K9 (in the passband).

regards

Last edited by diegomj1973; 17th January 2013 at 04:08 PM.
 

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