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PostPosted: 12 Nov 2009, 13:13 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
:thumbsup: Great stuff. Enjoy your work.
Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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PostPosted: 12 Nov 2009, 16:52 
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Joined: 27 Aug 2009, 15:19
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Location: Sweden
Sorry for that missprint in formulan (1.141) should be 1.414 nothing else.

Kjell.


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PostPosted: 12 Nov 2009, 18:24 
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Joined: 08 May 2009, 08:20
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Location: Duesseldorf, Germany
Hej Olof ;-)

I'm glad to read that you enjoy your project and i must say, that you've done it very good! It's not very easy to build a amp just "from the scratch" as first time project. Great!

You can use the 22uF / 25V cap instead of the 35V cap. That shouldn't be a big problem, because this cap isn't connected to the supply voltage. This cap is a decoupler for the feedback and it also works as a frequency setting component. You can attach it to the circuit and change it later to 22uF / 35V - when you got this cap. I would change it later, if you want to drive the amp to the limit (for safety reasons only).

Some more little tips:
Be sure that the leads from the PSU to the amp are able to carry the current. Use 1,5 mm² wires to supply the amp boards.
You must be careful with the IC isolation. Be sure that the IC doesn't have a electric contact to the coolers. Use MICA or Silipads + thermal grease.
If you like to build the completed amp into an enclosure, be sure that it's vented, or the amp will heat up.
Connect the "MAINS EARTH" to the enclosure, if you want to use a metal enclosure.

Feel free to ask, if there any questions are left!

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 13 Nov 2009, 02:12 
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Joined: 04 Nov 2009, 01:45
Posts: 45
Thanks again! You've been very helpful. I'm glad that I finnaly got it to work and I gotta say it does not play bad compared to my dads NAD.

Cheers,
Olof


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PostPosted: 13 Nov 2009, 10:38 
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Joined: 04 Nov 2009, 01:45
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Too bad my crappy camera aren't able to pick up the sound very well. Now i'm waiting for the cabinet from Italy =)


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PostPosted: 18 Dec 2009, 02:29 
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Location: Duesseldorf, Germany
Hi all,

Just a little but important information about the power supply:

The power supply schematic has been updated this week (Dec. '09). The two 2.5A fuses on the DC power supply schematic have been removed!

Please omit the two fuses + holders, if you are working with the old schematic. Or you can jump / bridge the fuses with at least 5A slow blow fuses or copper wire if you already have built the power supply following the old scheme.

In some cases, the power supply will lose the symmetrical output, if only one of the fuses blows and the ICs will pass DC to the speaker outputs which could damage speakers.

Please refer to the new power supply schematic on the project page and thanks for regarding this info and for your cooperation.

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 10 Jan 2010, 20:58 
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Joined: 05 Jan 2010, 19:04
Posts: 6
I'm intrigued by your project, and I'm starting to line up parts to build one. I have a couple of questions. Would it be possible to power the amp with a "wall wart", or batteries? I have a boombox-style enclosure lying around and want to have something portable.
Alternately, if I went with the on-board power supply, could I use 1N4007 diodes for the bridge rectifier? I've got a bunch of those lying around at present.
cheers,
-p


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PostPosted: 11 Jan 2010, 15:29 
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Joined: 08 May 2009, 08:20
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Location: Duesseldorf, Germany
Hi all,

i hope you enjoyed the New Year's party without painkillers on the next day ;-).

Hi P,

it's hard to say, if a wallwart supply would work well with the TDAs. I've really no experience with using wallwarts for IC amps, but i would guess, that the current and the voltage from a wallwart supply is not enough to fire up the TDAs. I'll take a look on the specs again, to see, how "big" the supply must be, to get the TDAs working.

Using batteries isn't a good idea. They would run empty before you had a :yumcoffee:..
The onboard PS could be a good chance to get the stuff together. Do you know the AC output from the built-in xformer?? Maybe the current too??

Let me take a look, how much power you'll need from the power supply at least..

Yep - you could use the 4007 diodes. That depends on the xformers power... 4007 diodes can handle 1A p.e.

Talk to you soon...

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 12 Jan 2010, 16:09 
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Joined: 08 May 2009, 08:20
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Location: Duesseldorf, Germany
A voltage at about 12Volts + and - with about 600mA per channel would be enough for the "boombox".
If you want to engage a single supply (unsymmetrical supply, without a negative rail) you'll need some more components on the TDA circuit.
The circuit layout for use with a single supply is shown on the datasheet.
Attachment:
tda_pwr_vs_supply.gif
Here you can see the power supply voltage vs. the output power. I think it helps making a choice for the supply.


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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 12 Jan 2010, 18:58 
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Joined: 05 Jan 2010, 19:04
Posts: 6
Wow, thanks for the lengthy and detailed posts Tom. You're very thorough. I'm off to the local elecronics district here in Kaohsiung City today, I'm not sure if they have those nice dual-output toroidal transformers that I see in most of the builds on the forum, but they do have a decent array of mono transformers on offer, so I'd use a pair of those and a slightly bigger enclosure. This is going to be fun.


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