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Volume Amp

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AtomSoft

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Hey guys i need to create a nice small amp something for a headset. Hopefully to fun on 1 or 2 batteries. I just need to boost the volume on a mp3 device but i want it to be for my headphones. So i can reuse on many devices.

Some thoughts on ICs or ideas?
 

MikeMl

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Most Helpful Member
Lm386.................................
 

AtomSoft

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i have a few i guess i need a datasheet lol im so lazy lol

BUT:
Wide supply voltage range: 4V–12V or 5V–18V

I need more of a 3v option. I guess i can look at the "Equivalent Schematic and Connection Diagrams" and try to figure how it works. and make a lower voltage amp

found LMC6572
 
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k7elp60

Active Member
I would think you need a power amp more like a TDA2822M or a MJM2073 both of which will work on 3V.
 

AtomSoft

Well-Known Member
ok is it safe to believe that a amp can be made using some transistors and resistors. Basically setup some different resistors to create different power voltages while using different transistors to switch the power ?

Like this:
FIRST AMP SCHEMATIC DELETED i had it wrong there.
here is what i mean:
 

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AtomSoft

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I read the first page of the below site and this caught my eye:

In order to register all of the minute pressure fluctuations in a sound wave, the microphone diaphragm has to be extremely sensitive. This means it is very thin and moves only a short distance. Consequently, the microphone produces a fairly small electrical current.

This is fine for most of the stages in the process -- it's strong enough for use in the recorder, for example, and it is easily transmitted through wires. But the final step in the process -- pushing the speaker cone back and forth -- is more difficult. To do this, you need to boost the audio signal so it has a larger current while preserving the same pattern of charge fluctuation.

This is the job of the amplifier. It simply produces a more powerful version of the audio signal.
from: HowStuffWorks "How Amplifiers Work"

and on page 2:
The pre-amplifier works the same basic way as the amplifier: The input circuit applies varying resistance to an output circuit generated by the power supply. Some amplifier systems use several pre-amplifiers to gradually build up to a high-voltage output signal.
NEW SCHEMATIC :
 
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AtomSoft

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Nigel why wouldnt the above work? it will use the same input and switch it using the same speed of the input but switching more power as the output so signal is the same but boosted. Why wouldnt this work?
 

audioguru

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Sound from headphones is produced by AC current.
Your transistors produce DC current which might destroy your headphones.

An amplifier has voltage gain.
Your pile of transistors and resistors have a voltage loss.

Your transistors are not biased properly so they will just produce severe distortion.
 

audioguru

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I simulated the "simple easy amplifier":
1) It is not biased correctly so the negative-going output swing is severely clipped.
2) It has a voltage loss instead of voltage gain.

I tried to fix it but it is too simple to be much better.
 

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audioguru

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The LM386 is a pretty good little amplifier. It has a basic voltage gain of 20 so you will need a volume control for it.
 
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