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Old 22nd December 2008, 06:56 PM   #151
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Quote:
Originally posted by pacificblue


Which is as true the other way round. 2 x LM1875 means per deinition 40 unprotected Watts. 1 x 3875 means 56 protected Watts, with the same component count as 1 x LM1875. Output power is similar enough to forget about it, price will be similar, complexity will be higher for 2 x LM1875. The only logical reason left to use 2 x LM1875 instead of 1 x LM3875 is to use it as a learning exercise.
Yes, of course a parallel LM3875 is worthy of exploration as well.
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Old 22nd December 2008, 07:04 PM   #152
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Quote:
Originally posted by gekkehenk
. . .
I've changed several things

The inducter changed to 5uH as the documentation says it should be.
The coupling cap is changed to 220nF polypropyleen 5%. Also following the documentation. Al other caps are polypropyleen 1%.

. . .
Most application guides that contain a speaker output zobel and specify the cap, also specify mylar/polyester/MKT.
These are available with either the appearance of a "box" or as a "dip cap" (looks like bubble) cap. It is the polyester film dip cap that is most specific for speaker output zobel.
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Old 23rd December 2008, 07:19 AM   #153
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Pay attention that there must be space for screwdriver between powercaps...
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Old 24th December 2008, 05:49 AM   #154
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Screwdrivers! Oh what an adventure that was.

First, solder a cap, then. . .
2 oz vodka
5 oz orange juice

Next, solder the other cap, then. . .
2 oz vodka
5 oz orange juice

Wow, pretty soon, I had some sort of artsy sculpture sort of power circuit with eighteen caps. This wasn't my best idea.
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Old 24th December 2008, 07:20 AM   #155
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Quote:
Originally posted by danielwritesbac
First, solder a cap, then. . .
2 oz vodka
5 oz orange juice

Next, solder the other cap, then. . .
2 oz vodka
5 oz orange juice
Finally the secret behind many of your posts is revealed.

Merry Christmas
David
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Old 24th December 2008, 07:44 AM   #156
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Quote:
Originally posted by pacificblue


Finally the secret behind many of your posts is revealed.

Merry Christmas
David

Merry Christmas to you too!

I finally found that thing! It actually has 20 caps (four are snubcaps). Without further delay, here's the not-recommended, too many screwdrivers = too many caps power supply:
Attached Images
File Type: jpg toomanycapspsu.jpg (23.5 KB, 1029 views)
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Old 24th December 2008, 05:23 PM   #157
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I,m a big step futher with my pcb design now!!

Click the image to open in full size.

I've build a variable regulated power supply with a LM317 and LM337.

4x 2200uF Nichicon PS series caps. Low esr and impedance.
2x 1000uF Nichicon PS series caps. Low esr and impedance.
Vishay 1837 series 100nF 1% MKP filtering caps.
The output coupling cap is an 220nF 5% Polyester.
At the input is a 2,2uF evox-rifa polyester coupling cap 5%
All resistors are 1% metal films.
The diodes are the Mur-860.



The layout is made by the document of the LM1875.

-The whole print is "euro" sized zo it will fit easy in many housings from 5cm or higher.

- Input and output is as far away as possible from the power supply rails for minimal distortion.

- The ground for the input and output is not connected with the ground from the power supply.

- The ground wire from the transformer is in center point of the rails between the big caps and the voltage regulators.

- Power supply is futher off the Lm1875 for minimal distortion.

The only problem are the voltage regulaters. I didn't know that they could not deliver 1,5 amps at high voltages....oops. So i'm going to use a buffer transistor for both sides?

I,ve looked for other 3amps voltage regulaters, positive and negative but i couldn't vind any pairs. The only one i could find as best match was the LT1083 with the LT350 form Linear.

Does anyone know a better combination with minimal components?

Waiting for comments

Thanx!
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Old 24th December 2008, 05:23 PM   #158
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Oh, i almost forgot!


Merry cristmas everybody!
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Old 25th December 2008, 09:53 PM   #159
zikinho is offline zikinho  Croatia
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Any experience with the PSU voltage regarding the sound? With what kind of rail voltage did you get the best sound?

P.S. Merry Christmas everyone.
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Old 26th December 2008, 02:49 AM   #160
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Quote:
Originally posted by zikinho
Any experience with the PSU voltage regarding the sound? With what kind of rail voltage did you get the best sound?

P.S. Merry Christmas everyone.
No, I haven't built it yet so I really don't know. I was planning to use a rail voltage from 28 to 30 volts.

Greetings
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