If TDA7294 Can work in 30V AC transformer - diyAudio
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Old 2nd June 2010, 03:48 AM   #1
guaxian is offline guaxian  China
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Default If TDA7294 Can work in 30V AC transformer

TDA7294 PDF says it max V. is 40V DC, But my transformer is double 30V AC, Will it broken?
Anybody try to use hight voltage in use
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Old 2nd June 2010, 05:09 AM   #2
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Yep, you'll definitely blow it up with such a high voltage transformer. Even the TDA7293 which can stand 50V will be a tad marginal with such a transformer, unless its regulation is 7% or better.
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Old 2nd June 2010, 05:26 AM   #3
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Thanks Abraxalito, But I will still keep trying, If Broken
I will reply here.
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Old 6th June 2010, 05:57 AM   #4
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You could use your transformer in Center Tap config with just 2 diodes (total), in the center tap specific full wave rectifier. . . pretty much just exactly like a vacuum tube rectifier.
Link ---> File:Fullwave.rectifier.en.png - Wikipedia, the free encyclopedia
This makes approximately 22vdc,0,22vdc after rectification

or, you could use a regulated power supply
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Old 8th June 2010, 07:01 AM   #5
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Thanks for reply!
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Old 11th June 2010, 06:28 AM   #6
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Hi everybody, This is Vedmitrasharma from City of Tajmahal . Can somebody guide me how to parrellel T D A 7294 I.C.s to get more current power to drive subwoofers as the have done with L M 3886 in Berringer moniter box with 3 I.C.s .regards everybody .waiting for reply
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Old 23rd June 2010, 01:29 AM   #7
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Quote:
Originally Posted by vedmitraa View Post
Hi everybody, This is Vedmitrasharma from City of Tajmahal . Can somebody guide me how to parrellel T D A 7294 I.C.s to get more current power to drive subwoofers as the have done with L M 3886 in Berringer moniter box with 3 I.C.s .regards everybody .waiting for reply
I just had TDA7293 with 3 I.C.s. Working fine in +/- 45V!
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Old 23rd June 2010, 01:32 AM   #8
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Hi all, I have input 30V AC on TDA7294, Working for two weeks,
It's working fine and the TEMP is no hight, TDA7293 may be safe on +/- 42V DC.
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Old 16th May 2012, 05:18 PM   #9
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Quote:
Originally Posted by guaxian View Post
I just had TDA7293 with 3 I.C.s. Working fine in +/- 45V!
hi guaxian,
can u send me this 3 ic shcematic and pcb details thanks
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Old 16th May 2012, 07:25 PM   #10
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The first three words of the TDA7294 specheet: "ST", "TDA7294" and "100V".
I would have no problem running it on a 2x30V~ transformer.

Infact I did...

I made a PCB for the class G/H application of the TDA7294 and this is in the specsheet as being run of off +/-20 and +/-40. I had a custom transformer wound for it with a 2x30V secondary (and 2x15). It worked for a few months, and then it indeed blew up . But I have no indication the voltage caused it. It had other issues, like clipping at 25V with a +/-20 and +/-40V supply

As for paralleling it: it can be done (there's a commercial amp discussed on here somewhere with (iirc) 12 bridged sets of TDA7294's that can be paralleled to one channel).

But the TDA7293 has a special feature for it (never looked into it as I am stuck with a load 7294's due to the above mentioned failed project) but supposedly it is like a master-slave function and doesn't even need extra resistors. So it would be far easier to do it with a 7293.


Edit: another quote from the specsheet:
Quote:
The TDA7294 is a monolithic MOS power amplifier
which can be operated at 80V supply voltage
(100V with no signal applied) while delivering output
currents up to 10 A.

Last edited by ric-paul; 16th May 2012 at 07:46 PM.
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