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F5X -- the EUVL Approach
F5X -- the EUVL Approach
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Old 28th November 2011, 10:23 AM   #591
EUVL is offline EUVL  Europe
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No fixed rules, just what I feel like.
Normally around 1/1000 to 1/20000 of the main C.

A good reference :

http://sound.westhost.com/power-supplies.htm

But feel free to experiment.


Patrick
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Last edited by EUVL; 28th November 2011 at 10:47 AM.
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Old 28th November 2011, 10:59 AM   #592
Murdoc is offline Murdoc  Germany
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F5X -- the EUVL Approach
Tanks a lot!
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Old 28th November 2011, 12:11 PM   #593
ashaw is offline ashaw  Australia
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A large capacitance has a large paracitic resistance and inductance in series with it. Adding a smaller capacitor improves the Power supply's high frequency response. A value of between 1uF and 10uF is appropriate after the reservoir capacitor. In high speed digital logic at least a 100nf cap should be plased next to each IC. With several such caps and several pF range caps also often being added.
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Old 28th November 2011, 01:53 PM   #594
jameshillj is offline jameshillj  Australia
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Bipass caps often produce complicated higher freq resonances, so you sometimes have to consider adding specific value 'snubber' ccts (R-C) to the paralleled capacitors to get the best results.

Fortunately, some combinations seem to work okay without the extra damping/filters but many don't - plenty of source material available about 'snubber' design, and other threads here, too.
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Old 28th November 2011, 02:45 PM   #595
dnewman is offline dnewman  United States
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Quote:
Originally Posted by ashaw View Post
In high speed digital logic at least a 100nf cap should be plased next to each IC. With several such caps and several pF range caps also often being added.
While completely off-topic, I found the following recent article to be a nice illustrative write up of this,

Decoupling by Example

It seems that during a recent 74xx TTL contents, many of the entrants lacked use of bypass capacitors....

Dan
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Old 9th December 2011, 03:40 AM   #596
EUVL is offline EUVL  Europe
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Just a teaser from the test team.

Smyslow sent me a square wave response of his F5X proto currently using 2SK1530 / 2SJ201 output devices, and 2SK170 / 2SJ74 front end cascodes.
Red is input; blue is output.

Fitzfish, meanwhile, also has his standard grounded X measured with some excellent distortion results.
But I'll leave him with the honour to tell you.

So we are making progress.




Patrick
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Last edited by EUVL; 9th December 2011 at 03:43 AM.
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Old 9th December 2011, 05:42 AM   #597
fitzfish is offline fitzfish  United States
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Thanks Patrick.

It is exciting to see them working. I'll start with a taste of the measured performance and promise to post many more in the upcoming build thread.

This is THD in the grounded X configuration, 1W into 8 ohms. After some additional testing I'll be switching to floating X.

The total harmonic distortion is around 0.0006%.

More to come!
Dave
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Old 9th December 2011, 07:27 AM   #598
chalkandtalk is offline chalkandtalk  United Kingdom
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Exciting and thanks for posting. Looking forward ti building even more now.
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Old 9th December 2011, 10:12 AM   #599
johnwmclean is offline johnwmclean  Australia
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Exciting news, excellent results.
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Old 9th December 2011, 10:26 AM   #600
EUVL is offline EUVL  Europe
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You can see the balanced circuit and the good matching at work here, as all even harmonics are almost 10dB smaller than the next odd.

Only when you see distortion spectrums like this do you realise why there is so much fuzz about matching, .. etc.




Patrick
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