# [SOLVED] LM383 Amp [help]



## hobby_guy (Nov 14, 2011)

Hi, I when to my electronic store and ask for the LM383 but they didn't have it so they told me that the TDA 2002 is the same thing so I have that using instead of the LM383.

So I build the 7Watts amp with this TDA 2002 but the thing I'm having trouble is that with two nine volts battery it just makes a weird sound but with the one 9V I could hear it, and pretty loud too, but it doesn't sound clear I would describe it as distorted, and I was told that this amp could be power 5 to 20V so if you could tell me whats going on to be able to hear it rite and clear. Well thank you and for any comment.


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## octaneman (May 13, 2009)

*Re: LM383 Amp [help]*

Hi hobby guy 


Your circuit has been set up as a band-pass filter, which means your circuit cuts off fequencies that are too high or to low. When you turn the volume down what you effectively doing is attenuating, meaning you are reducing the amplification that goes to the speakers. The problem with these circuit is that it blocks frequencies on both sides of the spectrum, only the frequencies that you select will pass through the filter.



Question: What type of amplifier are you attempting to build ?


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## hobby_guy (Nov 14, 2011)

*Re: LM383 Amp [help]*

yes when I turn the volume up it sound distorted and when I turn it down it sound better but sorry but I don't understand what you mean by the only frequencies that I select will pass through the filter.

And thank you for the comment.


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## octaneman (May 13, 2009)

*Re: LM383 Amp [help]*

hobby guy,




What I mean is when you drew your band-pass circuit you need to calculate your capacitor and resistance values which frequency ranges you want to hear through your speakers. Remember, the band-pass circuit cuts off low and high frequencies. 



On your LM383 circuit on the output pin the capacitor values are different than on the TDA2002. On pin 5 of the TDA2002 it has 2 capacitors in parallel one is 100 mf while the second is 0.1 mf. The LM383 has only one capacitor at 0.2 mf.


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## hobby_guy (Nov 14, 2011)

*Re: LM383 Amp [help]*



octaneman said:


> hobby guy,
> 
> 
> 
> ...


Thank you so much octaneman but I still have a lot to learn, this is easy for you since you know all this but I wouldn't know how to calculate the capacitor and resistance values for the frequency ranges for the speakers.

But thanks again octaneman....:smile:


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