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Chip Amps Amplifiers based on integrated circuits

eBay mono LM1875 kit
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Old 16th September 2019, 08:18 PM   #121
chermann is offline chermann  Austria
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hi again
last post for tonight.
my 12 Watt max look like a better TDA chip. because at the 2030 its written at 18V rail a may power of 9Watt. TDA2040 shows at 17V rail 12 Watt...
22Vrail is at the datasheet 8R TDA2050

hmm...
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Old 16th September 2019, 08:31 PM   #122
blackdod is offline blackdod  Europe
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Without magic smoke there is no glory

I have used mine with +/- 20V and without problems
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Old 16th September 2019, 08:38 PM   #123
chermann is offline chermann  Austria
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hi
i am impatient...i did it!
i set the chip on 20V rail and it worked fine. so now its a TDA2040.
correct?

i let the amp run on its clipping border = 500mVrms with my sweep 5 minutes at 8R and its survived. the chip has 59°C then i stopped and cooled with fan.


pic 1 is the consumption during 500mVrms 1khz on 8R
pic 2 is the scope probe ...its about 11,1V rms = 15,5 Watt


chris
good night
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Old 16th September 2019, 08:43 PM   #124
chermann is offline chermann  Austria
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Quote:
Originally Posted by blackdod View Post
Without magic smoke there is no glory

I have used mine with +/- 20V and without problems

Hi Jose
yes...i have a lot of kits with fake lm1875...so if something happened...TDA have to pay for
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Old 16th September 2019, 09:59 PM   #125
kurtvisti is offline kurtvisti  Denmark
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Quote:
Originally Posted by blackdod View Post
Without magic smoke there is no glory

I have used mine with +/- 20V and without problems
I supplied mine with +/- 26V and of course it went off in smoke.
Lesson learned: China PCBs ok. Components in the bin.

Or what do you all think?
Are any China Components ok?
Resistors perhaps?
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Old 17th September 2019, 05:59 AM   #126
chermann is offline chermann  Austria
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good morning kurtvisti


yes the pcb is ok. the components are maybe not the best but using +/-26V per rail is not recommended to any of these chips. TDA2030,2040, 2050 not more then 25V- datasheet .....the lm1875 is ok with +/- 30V at 8R and not at 4R!
actually my TDA2040?- fake 1875 is running since 90minutes with 20V per rail with a sweep of 10hz-35khz with 100mVrms. and the temp is on the chip 48°C. this is fine....don“t forget that no genuine TDA2030,2040,2050 is active or will be produces - so we have to expect a fake.
as i wrote i am surprised with the amazon kit that this chip can handle 25V per rail and give the recommended 20WAtt at 8R

so its definitive no TDA2030 - know i believe its a better one. its important to check because my transformer is a 18 -0 -18V AC = 25V DC.



chris
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Old 17th September 2019, 06:20 AM   #127
chermann is offline chermann  Austria
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Smile 25V rail ... no smoke

Hi


i did it !....25V per rail and no smoke


pic 1 idle
pic 2 +3 1khz with 100mVrms at 8R
pic 4+5 1khz with 600mVrms at 8R near clipping

13,1 Vrms on the scope give me 21,4Watt at 8R calculated...


so my chip is fine
chris
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Old 17th September 2019, 06:26 AM   #128
kurtvisti is offline kurtvisti  Denmark
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Quote:
Originally Posted by chermann View Post

i did it !....25V per rail and no smoke
And you have let the power on for a longer period of time?
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Old 17th September 2019, 07:00 AM   #129
chermann is offline chermann  Austria
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Hi
Now ist Running with 70mvrms Sweep at 8R. 30 min...no Problem with 25v tail.
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Old 17th September 2019, 07:45 AM   #130
blackdod is offline blackdod  Europe
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Good morning.



+/- 26V is out of specifications, so magic smoke is a logical consequence.

I know that TDA have been off the production line for years but I don“t know another chip that has similar characteristics to LM1875. In all the websites I have consulted they talk about TDA models.


The good news for all (thanks to Chris's tests) is that the fake chip is good enough. How much? I do not know
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