Hi everyone. I'm involved in a personal learning Project of making a simple audio amp for my Smartphone. I'm using a LF351n that requires a V+ and V- and i've used the virtual ground technique for achieving the voltajes with 2 9V batteries. The thing is that i don't seem to get a proper performance out of the circuit, so i believe the power supply could be the problem.

My question is what else could i use to power my circuit? I would like to keep it portable, so AC isn't an option.

Thanks everyone in advance.

 

Post your circuit, and it probably would be better to use higher current batteries.

 

The LF351 has a pretty weak output current. If that's all you have, you can barely light an LED, let alone a speaker.

 

The LF351 has a pretty weak output current. If that's all you have, you can barely light an LED, let alone a speaker.

Wow, i didn't realized that was happening. Should I go for a LM 368?

 

Post your circuit, and it probably would be better to use higher current batteries.

This is a very simplified schematic:

 

An LM368 is a voltage reference.
You need an audio amp.

 

An LM368 is a voltage reference.
You need an audio amp.

My mistake is that somewhere I saw an audio amp using a 368. What would you suggest me?

 

How about an LM386?

 

How about an LM386?

386 yes! but does it need a lot of power? i would like to use portable power.

 

386 yes! but does it need a lot of power? i would like to use portable power.

The chip doesn't use up power compared to how much the speaker does.
This is like asking if the steering wheel gets good gas mileage.

 

The chip doesn't use up power compared to how much the speaker does.
This is like asking if the steering wheel gets good gas mileage.

Great analogy, so this means that maybe i'm too ambitious with trying to drive a speaker with batteries or any other portable power?

 

My mistake is that somewhere I saw an audio amp using a 368. What would you suggest me?

For maximum battery life you want a Class D (switching) audio amp such as this.
It can be powered from three AA or AAA batteries in series.

 

Millions of, "boom boxes" have been sold. Are you too ambitious to try to do something that has been done so many times before?

 

Millions of, "boom boxes" have been sold. Are you too ambitious to try to do something that has been done so many times before?

I get it, the thing is that i don't know how to properly do it. my approch is flawed.

 

For maximum battery life you want a Class D (switching) audio amp such as this.
It can be powered from three AA or AAA batteries in series.

Battery life is very important, but will output be sacrificed?

 

Battery life is very important, but will output be sacrificed?

Are you kidding? Everything we say, you ask if it makes something else not work.
Sure, we sit here and give bad suggestions so you will fail, no matter which one you believe.
Is that what you think?

 

Are you kidding? Everything we say, you ask if it makes something else not work.
Sure, we sit here and give bad suggestions so you will fail, no matter which one you believe.
Is that what you think?

No you misunderstood me. I'm new so you should know that i have questions and that I don't know anything, I'm learning and that's normal and also i don't believe that people he want to intentionally misguide others.

Maybe I should leave.

 

Battery life is very important, but will output be sacrificed?

Sacrificed how?
Did you look at the data sheet to see if it meets your requirements (which you haven't stated)?