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Low wattage amplifier with volume control

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frankwas

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Hi.

I'm looking for an amplifier circuit that will boost low level output just slighty so that my PC's input will pick it up nicely, so that the recoring level isn't so low. The amp must be as small as possible, use a wall adaptor 12V 500mA or less to run and it MUST have a volume control.

Does anyone have suggestions?

Thanks,

Francois.
 
frankwas said:
Hi.

I'm looking for an amplifier circuit that will boost low level output just slighty so that my PC's input will pick it up nicely, so that the recoring level isn't so low. The amp must be as small as possible, use a wall adaptor 12V 500mA or less to run and it MUST have a volume control.

Does anyone have suggestions?

This is called a preamplifier, it's very simple and easy to make, using just a single opamp - you can specify the gain witht he feedback components, making one a variable resistor for your volume control.

However, you don't say what you are wanting to amplify, and this affects the design of the preamp, mainly the input impedance - but it depends what you are trying to do, a magnetic phono pickup requires a very different preamp.
 
I'm trying to boost the sound going out of a mixer and into a PC. But the output volume is too low for recording. Can you point me to a circuit design pls?
 
frankwas said:
I'm trying to boost the sound going out of a mixer and into a PC. But the output volume is too low for recording. Can you point me to a circuit design pls?

The output level from a mixer should be at line level, and can probably provide considerably more than that. If it's too low you've probably got a fault somewhere - I'm presuming you've got the record levels turned up on your PC software, and the correct input selected?.
 
Maybe the mixer made a small signal level intended for a microphone input? That's a bit lower than line level. Do you also have a mic input in addition to a line level input?

Frankly, I'm surprised your computer doesn't have an input gain to fix this. If it's a Windows machine, there's a control panel separate from your recoding tool to control line in level and it may be set too low.

An op amp does the job nicely. But be sure you get a low noise op amp like a TL082 or TL084, others can add a hiss to small signals which is noticible during quiet periods.
 
GraveYard_Killer said:
try to look for an LM386 amplifier

That's a power amplifier, not a preamplifier, not suitable at all - although it would work, but somewhat crudely with poor performance. It's also more expensive than a simple opamp.
 
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