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TDA7052 didn't work even with an Op-Amp before it

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foxbrain

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i need a circuit that takes my voice (via microphone) and hear it by speaker for now.... and later i want to convert my voice to digital..
for the first step i connected a circuit as in the TDA7052 datasheet but i didn't hear anything and on the oscilloscope i just saw a small noise signal.
i added an op-amp amplifier to it but same results!!!
So how can i solve this problem...
Thanks
 

Are you amplifying the microphone output. The mic output is too low to drive the TDA7052 without being amplified.
 

you should make a simple pre-amplifier circuit, which will take weak input signal from microphone and will produce an good strength signal for ADC to work upon..
 

You showed two identical mic preamps but they use the very old and noisy LM358 dual opamp as an inverting amplifier with a very low input impedance that shorts some of the fairly high impedance signal from the electret mic but they should work. The preamp opamp should be a low noise audio opamp (TL071 for example) as a high input impedance non-inverting amplifier.

The "camera" mic preamp does not work with voice or music since it is biased only to detect the POP of a balloon breaking.

You did not show the schematic of your TDA7052 power amplifier.
 

so what should i do???
the schematic of TDA7052 is the same one in its datasheet, anyway its not the problem because when i put the probes of the oscilloscope before and after the amplifier nothing changes.....
 

The amplifier in the datasheet for the obsolete TDA7052 has a voltage gain of about 90 and should reproduce the signal from a microphone if the mic is connected and powered properly.

The amplifier in the datasheet for the newer TDA7052A shows its DC volume control on pin 4. If pin 4 is below 0.3VDC then the amplifier is muted with no output.
If pin 4 is +1.4V to +8V then the gain is about 50 and it should reproduce the signal from a mic if the mic is connected and powered properly.

What kind of mic do you have: crystal, dynamic, 2-wires electret or 3-wires electret?
If you have an electret mic is it powered properly and did you use a coupling capacitor from it to the input of the amplifier?
 

so i shouldn't just use the tda7052 alone... so what amplifer is the best in this case?
the microphone i'm using is a very simple, it isn't an electric one and it got 2 wires only. this image got the same microphone of mine......
 

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The obsolete TDA7052 has enough gain for a properly connected and powered electret mic if you speak loudly close to the mic.

The 2-wires electret mic has a ground pin that is connected to its metal case and a signal/power pin that should be powered through a 6.2k ohms from 6V.
A 620 series resistor and a 100uF capacitor to ground can decouple the 6V for the mic power.

The input pin 2 of the TDA7052 needs a resistor to ground for its bias current and as a 0V reference voltage.
A 0.33uF film capacitor can be the input coupling capacitor from the electret mic and it passes frequencies down to about 41Hz.
Here is a schematic:
 

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i had just tried your circuit schematic but it didn't work either...
it is giving me at the pin 5 and 8 a signal which is as a sin wave with an amplitude about 5v and 1.5us frequency.... and nothing is changed while talking.........
 

1.5us is 667kHz.
Most modern audio amplifier circuits oscillate at a high frequency when built on a solderless breadboard.
On a pcb the circuit will work perfectly.
 

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