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Chip Amps Amplifiers based on integrated circuits

TDA7293 - Need help on circuit
TDA7293 - Need help on circuit
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Old 8th April 2005, 05:54 AM   #1
Fossil is offline Fossil  Singapore
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Default TDA7293 - Need help on circuit

Hi All!

I found the following circuit at http://home.s-planet.de/t.dauner/7293/

It is quite similar to the one which was published in UB electronics some time back.

Can someone explain the function of the caps/resistor network between Pin 2 & 14. The recommended circuit has only 1 resistor between those pins.

Thanks!
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Old 9th April 2005, 05:24 AM   #2
wxn is offline wxn  Lithuania
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100u caps are there to set DC gain to 1
R103 - feedback resistor
C3 prevents oscillation
C1 bypasses 100u caps
R1 - don't know for sure
R102 - gain setting resistor
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Old 9th April 2005, 09:51 AM   #3
boholm is offline boholm  Denmark
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It is a filter. It cuts away frequencies out of the audio band ( 20 Hz - 20 kHz).
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Old 20th July 2017, 12:17 AM   #4
CaseSensitive is offline CaseSensitive  Australia
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so C3 should be 47pf, better don't change it?
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Old 22nd July 2017, 08:55 AM   #5
AndrewT is offline AndrewT  Scotland
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C3 can increase the risk of oscillation.
It also allows interference brought in via the speaker connections to be injected into the -IN pin and get amplified.

Better to start with a low value 2p2F or 5pF and add a series connected resistor somewhere between 5k and 51k. A variable resistor of 50k or 100k can be used to tune the effect of C3.

C102+C2 are too small in comparison to C101
try a pair of 150uF, or 220uF, or for extended low bass 330uF, or 470uF

The gain seems to be set quite high. Do you have a reason to want this high gain?
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Old 22nd July 2017, 10:49 AM   #6
scottjoplin is offline scottjoplin  Wales
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Quote:
Originally Posted by wxn View Post
100u caps are there to set DC gain to 1
R103 - feedback resistor
C3 prevents oscillation
C1 bypasses 100u caps
R1 - don't know for sure
R102 - gain setting resistor
Surely R1 is the feedback resistor?
Only just realised this is an old thread
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Old 22nd July 2017, 11:58 AM   #7
JMFahey is offline JMFahey  Argentina
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Better get a De Lorean DMC-12 car, you are answering 12 y.o. questions
Click the image to open in full size.
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Old 22nd July 2017, 01:03 PM   #8
AndrewT is offline AndrewT  Scotland
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The question is new. The answers pertain to that question.
Old information can be just as relevent as current information.

There is nothing wrong with searching for a topic that contains the answers one needs, or contains details that are similar to, or even identical to what one wants to do now.
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Old 23rd July 2017, 12:09 AM   #9
CaseSensitive is offline CaseSensitive  Australia
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I mistaken it with another one. I got 15pF there. My design has a bandpass in it, lhe lowpass cap is pretty small. Was reading that post at work, not enough time to look at it.
R1 would be feedback resistor, together with R102.
AndrewT is right, C101 is for low frequencies, but C2 and C102 for mid. I calculated 3 differnet setups for low, mid and high drivers. Its all happening now. They are not oscillating.

I got a similar design from back then, but only now I got around to finish the build

Last edited by CaseSensitive; 23rd July 2017 at 12:17 AM.
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