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PostPosted: 25 Jun 2014, 13:09 
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Joined: 23 Jun 2014, 22:03
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i ve terminated all the ground at a single point.......
and is an exact copy of the given circuit
as in datasheet of tda2050 by st


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PostPosted: 26 Jun 2014, 18:35 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Hi cyberadi3,
Can you post a photo? Is there also DC offset on the output? Based on the symptoms, grounding would be my guess.

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: 07 Oct 2014, 11:22 
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Joined: 07 Oct 2014, 10:44
Posts: 4
Location: Athens, Greece
Hello there!

First, thanks for this great topic, I have wandered around many times while building a tda2050 single supply amp. It will be used as the power amp section of a small guitar amp.
First thing i did was to transfer the single supply layout to stripboard and build it with success. I tested it with 2 9V batteries and it sounded ok as far as i could tell.
Then i built the PS based on the schematic of this project. The transformer used was a 15-0-15 with the center left floating. The caps i used are rated for 60V or more. The diodes are taken out of an old VCR - so that's probably a weak point. I can't even find their specs anywhere on the internet...
The only component that is different is the 1R resistor that i didn't have - so i used a 2R2 2W. The power supply seems to work fine except for the audible ripple that has to do with mains AC frequency i suspect. The boards are not in a case so I also suspect that my grounding is far from perfect. I just connect the grounds from the boards together and the speaker ground to the negative side of the 2K2 resistor in the PS.
Also the wires that connect the PS to the amp board are rather thin, could this be another reason for hum?
The hum goes away as i feed the amp with more signal (another clue).
The power supply is also on stripboard!

attached are some bad quality images. 8-)

ps - I am self learning electronics, the whole process includes a lot of trial and error - this time I don't know how to proceed... thanx for any advice in advance!!!

Sot.


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PostPosted: 07 Oct 2014, 15:01 
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Joined: 07 Oct 2014, 10:44
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Location: Athens, Greece
Further investigation shows that placing a 1000uF cap in parallel with the 10000uF reduces the hum. So maybe with greater capacitance, perhaps 4700 it could be reduced more?


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PostPosted: 08 Oct 2014, 21:16 
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sotkouv - the hum could also be picked up from nearby wiring or could be due to grounding. Make sure the inputs are not close to the transformer or any AC wiring. 10,000uF should be plenty.

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: 09 Oct 2014, 03:33 
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Joined: 07 Oct 2014, 10:44
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Location: Athens, Greece
thanks a lot, i think I'll try to put everything in a metal enclosure, experiment with the grounding and see what happens!


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PostPosted: 20 Oct 2014, 11:12 
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Joined: 20 Oct 2014, 09:58
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My first post on this forum - thanks to everyone involved in this project.

Here are some basic questions about the amp of which I cannot seem to find a clear answer. This is my first approach to amp building so I apologize if they are too basic.

1.) What is the desired input impedance of the audio signal?
2.) If I wanted to limit the output power of the amp to 12W for my specific speaker, what will be the most elegant solution? Should I keep the input level limited or lower the overall gain of the amplifier?
3.) If I want to add a switch for selecting between two inputs (RCA and mini stereo jack), will a basic toggle switch affect the signal in a negative way?

Thanks in advance.
Warm Ragards,

Chris von Wielligh


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PostPosted: 26 Nov 2014, 14:37 
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Joined: 28 Jan 2014, 16:37
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BBM3 wrote:
Hello Tom,
The heat sinks I found at a local surplus electronics shop these are the only two they had. (Bummer)
The TDA2050's run ~40C driving 94dB 8 ohm speakers very loud.


Can u tell us a product part number for the heat sinks. I really want to get my hands on a set :)
Thank you in advance.


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PostPosted: 23 Dec 2014, 06:58 
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Joined: 28 Jan 2014, 16:37
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some pictures with my 4 modules of tda2050 :)
I will replace the matsushita caps 470uf/63v with some nichicon fg 470uf/63
And I am waiting for my wima to arrive. :)

http://postimg.org/image/jagvar2al

http://postimg.org/image/f5hebmez3


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PostPosted: 27 Dec 2014, 21:41 
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Joined: 27 Dec 2014, 18:44
Posts: 3
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.

Also I noticed during this thread that the versions of the PCB layouts have been updated several times. Which PCB and PSU layout is the correct one?

Thanks a lot :)


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