Hi, i want to use a 5 volt source and i want to increase the audio output of this circuit. How to do?

 

How much change to the circuit can you accept? I'd replace it entirely.

 

Do you want to increase the voltage, or current capability, or both?

To begin with:

- Remove R3, it does nothing useful
- If you remove R2 and connect RV2 directly to the battery you can adjust the gain over a much larger range
- Increase the capacitor sizes to about 47uF if you want the circuit to be useful over the whole audio range
- Add a small resistor to the emitter of Q1. Or better yet, add a larger, partially bypassed resistor to the emitter of Q1 and increase R_ear

What kind of output level do you want?

 

Hi, i want to use a 5 volt source and i want to increase the audio output of this circuit. How to do? View attachment 102553

A chip is much easier - the TDA7052 works well down to 5V, but its a BTL so not much good for earphones if you need stereo.

The A suffix part has DC volume control.

 

Thanks guys. I Will try the veracohr suggestions. This Circuit comes from a spy ear toy. I wanted to have much gain. I am working to a hearing empaired project

 

Thanks guys. I Will try the veracohr suggestions. This Circuit comes from a spy ear toy. I wanted to have much gain. I am working to a hearing empaired project

My TL431 electret capsule booster was published in Elektor a few years ago - someone here has a link to an online copy of the article.

The device is based on a 2.5V reference, so 5V would be cutting it fine - but might work well enough with 32/64 Ohm earphones.

With 12V supply it runs slightly warm loaded with an 80R speaker, its "comfortable" with a 140R telephone earpiece.

The TL431 can be had in TO92, SMD, 8-DIL and SOIC-8. With a small handful of passives you can be up and running. You can use a logic level MOSFET for more output drive, but biasing is easier if you use an interstage coupling transformer.

 

Thanks but i am a beginner. I dont Know if i can!

 

I know how, as a beginner, it seems easier to use discrete components. This is not true, and I encourage you to look at integrated circuits. Yes they are complex on the inside, but that is not your problem. They are designed by teams of experts to do exactly what you want, and you usually have to do little but power them and connect inputs and outputs as described by the data sheet. You will get so much farther, so much faster, once you accept that. Designing your own transistor amplifier is challenging, and you'll never match what the pros have already done for you.

 

MikeML is a wizard with the TL431 so he got me curious. There is a low level amplifier in the datasheet.
I'm thinking about a 1000 ohm to 8 ohm audio transformer I bought at Radio Shack. Too bad most of them are closed now.
Oh well. If you have to go to an internet vendor to buy an audio transformer you will be more likely to get one that is right for the job instead of making the job right for the transformer.

 

I have some problem to Connect this device with one single battery. I think the problem is on the connection of the max4466 electret. It has a common ground and it make me impossible the connection with the pam 8403 that have separate ground. Audio- and battery -. How can i Connect it properly? Maybe a diode?

 

Your pam chip uses a bridge output for each channel, it doesn't use a common ground.

Try a Tda2822 chip

 

No no. The problem is not in the output, but in the input. If i use a battery For each single chip. It Works.. How to Connect properly the pam8403 and the electret max4466? It's seems so easy.

 

You cant use the supply ground and signal ground together, they have to be separated, so you need to use two separate batteries., or a different chip.

datasheet

 

Maybe this can work. I need to find a dc to dc Converter 5volt to 3.3

 

You need an Isolated output Dc to Dc converter.

 

I know how, as a beginner, it seems easier to use discrete components. This is not true, and I encourage you to look at integrated circuits. Yes they are complex on the inside, but that is not your problem. They are designed by teams of experts to do exactly what you want, and you usually have to do little but power them and connect inputs and outputs as described by the data sheet. You will get so much farther, so much faster, once you accept that. Designing your own transistor amplifier is challenging, and you'll never match what the pros have already done for you.

The TDA7052 I suggested in an earlier post uses the absolute minimum of external components.

Literally; a supply, a decoupling capacitor, a speaker and a volume pot.

The A suffix part I mentioned has DC volume control, so the pot varies the DC bias on the control pin instead of dividing the input signal voltage.

Being a BTL amp, it also works well down to 5V.

 

Hey Ian field can you give me some suggestion to isolate the ground of power supply to the ground of audio?. I posted an image before.

 

You need an isolated dc to dc converter like one of these, choose one with your voltage range.

 

One For each chip?

 

No,just one it isolates the supply so you can use one battery or psu.