Voice changer faulty

Thread Starter


Joined Oct 22, 2011
Hi everyone, I build the telephone voice changer project for my final year project. The problem was, when I build and test it on breadboard, it doesn't give any output. I already check my connection and wiring but it still doesn't work. Was it my IC that I used are incompatible? please help me

LM358AN IC and datasheet

TDA7052 IC with volume control

Original circuits

Modified circuits


Joined Apr 16, 2010
It is impossible to say why it doesn't work. With the information you have provided, one can only guess.

What does it do? Have you built it exactly like the schematic? Have you substituted any components? Does the power LED come on? Does the speaker make a click when you turn the circuit on and off? Have you checked that the IC's are getting power on the correct pins? Is the battery connected correctly and providing a full 9 volts under load? State what you have tried and what the results were.

If you post a clear, close up photo of your assembly, it might be possible to see some issues.


Joined Sep 9, 2010
Divide and conquer. You can diagnose one thing at a time. For instance, does the audio amplifier work when there's a signal at J1? Check the bias and output voltages at the op-amps.


Joined Dec 20, 2007
The original project uses a TDA7052 power amplifier with a 10k log volume control and it works fine.
But somebody changed the circuit to v2.0 and used a TDA7052A that has a DC volume control that needs a 1M linear volume control. 10k will mute it all the time.
It will work if you replace the 10k log pot with a 1M linear pot.

Which website "updated" the TDA7052 to a TDA7052A (v2.0) but used the wrong pot?

Thread Starter


Joined Oct 22, 2011
hehe actually I forgot to change 10k to 1M on the sheet. I used 1M pot to this circuit. I do the design for ver 2.0 since the ordinary TDA7052 wasn't available at my market so I use TDA7052 with volume control. from ur opinion, does this 2.0 circuit work? I believe this circuit work since I only changed the IC TDA 7052 with adjustable volume ones. the other modification was just a minor (like adding LEDs and jack for microphone):)