Ampilfying Audio Output?

[LiNx]

Hey -

I have a pair of those speakers with the red and black wires coming out the back - not RCA, just a little red and a little black copper wire.

When I hook these up to normal headphone jack or an RCA jack, sound comes out, but only very, very quitely...

My question is, is there any way to ampilfy the sound before it goes into the speaker? It doesn't have to be variable, just at a comfortable level and I'll control the actual volume from the source. Sound quality really isn't that important - I want it to be half decent, but I won't be blasting the music.

Any help, even another web page would be great. The easier diagram the better - I'm a little electronically challenged.

Thanks
-LiNx

 

[audioguru]

An LM386 makes a simple speaker amplifier. It output power is only 1/2W when powered by 9V but is a lot louder than "very quiet". If it is played loud continuously, a little 9V battery won't last long. Then use a mains AC to 9VDC adapter instead of the battery.

 

[LiNx]

Okay, so the only way to do it is to buy one of those LM386 things? Where can I find one of them?

 

[audioguru]

The LM386 low power audio amp IC is available at most electronics parts shops in North America.

 

[Nigel Goodwin]

Okay, so the only way to do it is to buy one of those LM386 things? Where can I find one of them?

Not the ONLY way (there are a GREAT many possible solutions, certainly thousands of them!) - but the LM386 is a simple solution, low cost, and easily available.

 

[LiNx]

Great! Thanks.

 

[LiNx]

Is there something that I'm not understanding with national semiconductors samples? You mean... I just click a button, and they send me free stuff in the mail?? WHOA! There has to be something else... No?

 

[audioguru]

Make them think that you are making something that you will manufacture and sell millions. :lol:

 

[LiNx]

Wow! What an amazing plan!! Man, do I like your thinking :!: :!: :!:

 

[Thunderchild]

i've used TBA820's before and there r fine give 1.2 - 2 W output but the earlier proposal is fine it's up to u and what u can find

 

[LiNx]

Okay... So I'm finally getting around to building this thing.

Just clarifying some things...

1. All of things labbeled as 470uf, 0.05uf, those are capacitors, right? So are we talking like ceramic disk capacitors?

2. The little 10k variable resistor... Where can I get one of those from? Does this sound like the right thing - "10K Logarithmic Taper Pot"??

3. What in the world is a BYPASS??

4. All of the things that lead to ground, where do I actually wire those to?

Thanks
-LiNx

 

[Optikon]

Okay, so the only way to do it is to buy one of those LM386 things? Where can I find one of them?

Not the ONLY way (there are a GREAT many possible solutions, certainly thousands of them!) - but the LM386 is a simple solution, low cost, and easily available.

Yes also consider TDA series from st microelectronics.

https://www.st.com

If you find you need more power, they make similar devices that range from < 1W up to 100+W. I've done a 10W amp with a $2 part from them before..

 

[Dr.EM]

The 470uf is an electrolytic capacitor, it is cylindrical in appearance. The 0.05 can be a ceramic. That pot sounds fine. Everything with ground connects together and to the the "-" terminal of the battery or power supply. I think you ignore the bypass, unless you experiance problems such as oscillations or noise, then connect a 0.1uf capacitor as shown. I think the 20x gain is what you want though.

 

[LiNx]

Yes also consider TDA series from st microelectronics.

https://www.st.com

If you find you need more power, they make similar devices that range from < 1W up to 100+W. I've done a 10W amp with a $2 part from them before..

Thanks - I'll check them out.

The 470uf is an electrolytic capacitor, it is cylindrical in appearance. The 0.05 can be a ceramic. That pot sounds fine. Everything with ground connects together and to the the "-" terminal of the battery or power supply. I think you ignore the bypass, unless you experiance problems such as oscillations or noise, then connect a 0.1uf capacitor as shown. I think the 20x gain is what you want though.

Wow... That sure made this whole thing seem a lot easier... Thanks

 

[Thunderchild]

u could use a TDA 2009 to make a 2X10W amp. that is what i am about to do for my car and will put it in the cars ash tray to leave the car radio bay free for whatever source i choose.

 

[audioguru]

u could use a TDA 2009 to make a 2X10W amp. that is what i am about to do for my car

If you make an amp for your car you should check the datasheet and look for a 24V battery in your car. The TDA2009 isn't made for use in a car.

 

[LiNx]

Okay... What do you guys think about this??

The 6 line-in's all go through a 10k pot, and then an on-off-on switch where you can choose to put it through out1, mute it, or put it through out2. The amp's are going to be two of my little LM386 things.

I don't see why this wouldn't work, but can anybody point something out?

 

[audioguru]

The LM386 doesn't need a negative 12V supply. The total of your two supplies is 24V which is much too high for an LM386, and you have them shorted together anyway.

An audio mixer is made with a differential input inverting opamp that has multiple inputs that don't affect each other. The LM386 doesn't have an inverting input where negative feedback is applied.
On your circuit, if you turn down one or more inputs then they all will be lower.

I don't know why you are connecting the inputs of the LM386's to the power supply through 10k resistors. :cry:

 

[LiNx]

Okay... That last drawing was a result of my poor drawing skills and me trying to do stuff that I didn't have a clue about. So, here is the next drawing, which hopefully will be more clear. Does this look like it will work?

 

[Nigel Goodwin]

Okay... That last drawing was a result of my poor drawing skills and me trying to do stuff that I didn't have a clue about. So, here is the next drawing, which hopefully will be more clear. Does this look like it will work?

No it won't work, you can't just join the sliders of pots together, turning one right down would mute all the rest. You need to use a simple virtual earth mixer, between the pots and the power amplifier. Basically one opamp, one feedback resistor, and one resistor per pot - there are plenty of simple mixer designs on the net.