I have tried this model of LM1875 audio amplifier.. http://www.electronics-lab.com/blog...25w-hi-fi-audio-amplifier-using-ic-lm1875.jpg .. it makes a huge amount of distortion.... when the input volume is at a lower stage it is cristal clear...bt whenever i increase the volume the sound gets worser..i have used a 8ohm 3W speaker to get the output....more info: 1000uF cap. of 16V electrolitic,100nF 63V cap. of polyester,0.22uF of polyester(marked as 2A104J),1uF electrolitic of 50V,27uF electrolitic of 16V ...i have used 12V 2.5A transformer split voltage...and the most important part is that both the ic and the speaker get so hot...please help me!!!
the ic and the speaker get so hot...please help me!!!
Are you just over-driving your poor 3W loudspeaker?
Frank.
that's not likely the case...I built nemerous LM1875 amps, they run pretty cool, never too hot, assuming proper heatsink
even if you drive 3 watt speker pretty loud, it should not be too hot, that may indicate DC going through the coil, or the oscillation, as mentioned above
even if you drive 3 watt speker pretty loud, it should not be too hot, that may indicate DC going through the coil, or the oscillation, as mentioned above
did you check?did you check the DC on the output?
i used negetive pole of the capacitor to the ground and positive pole to (-12Ve)
boom fireworks display.
-12Ve to negative pole of capacitor and ground to + pole of capacitor
but that's for the -12Ve rail only.
Right, the positive lead of the capactor goes to the "most positive" part of the circuit. With a dual/split supply, this means the positive lead of the capacitor sometimes goes to circuit ground, because the negative lead goes to the negative side of the rectifier, which is "most negative."
But wait a second, just asking, here.
You say you use a "12V 2.5A transformer split voltage." Of course by this you mean a 24 volt center tapped transformer? Because a "split" 12 volts delivers +/- 6 volts, which of course won't work.
But wait a second, just asking, here.
You say you use a "12V 2.5A transformer split voltage." Of course by this you mean a 24 volt center tapped transformer? Because a "split" 12 volts delivers +/- 6 volts, which of course won't work.
im a newbie in this business...and that was a silly mistake..but i just followed the circuit diagram and there they made this mistake in their diagram... im using 12-0-12 transformer of 2.5A.....so after all these what do you think?...i mean what kind of change should i make to get a distortion free sound......
Yah...i found dc voltage when the amplifier was making distortion...bt when it wasnt making distortion (in lower volume input) i found no dc......i used 47k instead of 10k,distortion decreased,bt gain too
47k is a bit too high, 150k & 47K will give approx 4x gain. (The 1875 is "stable at gain >=10x ".)
about the noise.... maybe your power caps are not big enough. what size are you using (on the power supply board)?
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