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PostPosted: 30 Dec 2014, 13:15 
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Joined: 31 Dec 2008, 15:34
Posts: 441
vezilka wrote:
Hello, :)

I'm trying to build this project. I have one question tho...

I have these options available:

36V-AC(2x18V-AC), 100VA. which is 2.7 Amps http://www.loging.mk/en/2041/176818/0/S ... nsformator
30V-AC (2x15V-AC), 200VA. which is 6.6 Amps http://www.loging.mk/en/2042/179975/0/S ... nsformator

also my question is which fuse to use with each transformer.



Hi

If only these two options, you should go for the 200 VA, 6,6 A, even if it's only 2x15 VAC, simply because you want the higher current for the amplifier, instead of higher voltage and less current of 100 VA, 2,7 A.

After rectification you should see around 2x21 VDC ( remember that the max voltage/limitation for the TDA2050 is 2x25 VDC ).

More about transformators, in this tutorial from Tom: viewtopic.php?p=10032#p10032

Fuse for the 2x15 VAC transformator:

It depends ...we will take both a 115 and 230 V area calculation.

Generally you take the VA load ( In this case 200 ) and divide that by the input voltage ( 115 or 230 ). Then multiply that by ( 1,35 )

So 200/115 = 1,73 A or 200/230 = 0,87 A

1,73 * 1.35 = 2,33 A ( = T 2,5 A fuse ) or 0,87 * 1,35 = 1,17 A ( = T 1,25 A fuse )

If not a standard current rating for the fuse, always round up to the next available size. Also, use a SLOW BLOW type fuse ( often marked T ) ...don't use F in this case.


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PostPosted: 03 Jan 2015, 15:34 
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Joined: 27 Dec 2014, 18:44
Posts: 3
Hello again and thanks for your answer. It has been very helpful. Unfortunately the electronics store is out of the stock with the 15v-0-15v / 200VA so I'm left with the other choice. Hope I'll get a decent sound :headphones:


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PostPosted: 14 Jan 2015, 11:47 
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Joined: 14 Jan 2015, 11:33
Posts: 2
Hello all,

Four years ago i built one of these without any problem, and was pretty amazed with the sound quality of these TDAs!
But recently i built another unit that has some more stuff, but with the same amp circuit.
I am pretty sure the circuit is free of errors, but when I turn the amp on there is a lot of distortion and resistor r4 smokes out.. It is rated 2w as described.
Can anyone help me figure this out, please?

Thanks


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PostPosted: 16 Jan 2015, 11:37 
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Joined: 14 Jan 2015, 11:33
Posts: 2
The problem is solved.
Seems my circuit was generating positive feedback, causing the amp to oscillate.
Redesigned the circuit to the tda datasheet recommendations and now it works fine.
Thanks


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PostPosted: 27 Jan 2015, 19:53 
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Joined: 28 Jan 2014, 16:37
Posts: 4
A picture from Making of :)
Enjoy :)
Image


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PostPosted: 29 Jan 2015, 19:04 
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Joined: 27 Dec 2014, 18:44
Posts: 3
Hello again!
Everything is completed, used smaller heat sinks for the TDAs which combined with an additional fan stay slightly warm at hi volume. I really love how the amp sounds, warm, nice and no noise even at maximum volume.
Started to place the modules in the box, front and back panels are sent to be laser cut. This is my progress so far, I will be posting a final pic when I complete the box.

Image

Image

Image


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PostPosted: 03 Feb 2015, 13:15 
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Joined: 28 May 2008, 21:53
Posts: 4565
Location: Winnipeg, CANADA
Hi vezilka, real nice work on the PCB and layout. Enjoy the amp

Cheers

_________________
[ 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: 17 Feb 2015, 18:10 
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Joined: 24 Jan 2015, 16:18
Posts: 1
tombethe wrote:
Hi all!
...
I bought a 18-0-18 VAC or a 18VCT (Volt AC - centre tapped) transformer. Is that wrong? What can i do now??
Now - that's not a mess and you surely can use it. How?
Attachment:
centre_tapped.GIF
Just change the supply input a little bit for use with one (1) single rectifier bridge, because you don't need to build a "centered" PSU like the one above. The PSU is centered by the transformer because the transformer is (now guess what) - centre tapped ;-).
Whoops - why don't we use it as standard? Because the performance is slightly lower and centre tapped transformers (VCT) are not usual sold types. I want to say, that it's way easier to get a dual secondary type.


Hi,
I'm a complete newbie and I'm going through building the amp. Unlike said, I couldn't find a dual secondary transformer, only a center tap one. One thing I couldn't understand and I'd like some help: How can I wire the PSU to both channels ? It's one single board with parallel connection to the channels or two independent boards with parallel conection to the transformer ?

Thanks !


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PostPosted: 15 Jul 2016, 05:18 
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Joined: 15 Jul 2016, 04:22
Posts: 1
hello sir good morning to every body I am trying to make a amplifier with tda 2050 as shon in symatic with single tda 2050 25w , iam using either 4 oms or 8 oms speaker with 25 waccording to thids diagram link below http://diyaudioprojects.com/Chip/DIY-TD ... ematic.png
plzz help me about resistor r1 wich is of 22k r2 which is of 680 oms and r3 22k plzz tell me that if I can can the r1 r2 and r3 value like in chart it is given that r2 and r3 will increase and decerese the gain what it mean , can I put 5k pot isted of r2 680oms to control the gain plzzzz help me with this resistors value can I change it or not plzzz help me


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PostPosted: 17 May 2017, 13:59 
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Joined: 15 May 2017, 02:22
Posts: 1
Location: Italy
Hi I built the amplifier from your schema but without a potentiometer. So the problem that gets noise from a radio but at a very low level (they hear with ear attached to the speaker) that remain constant even by increasing the volume of the pre.I have checked The masses but nothing to do ... What can you depend (however the sound is very good)


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