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InterCom / Door Phone

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Don't you see that your new schematic has no input signal and has the 12V battery connected to the wrong location?
You also have R5 shorted.
 
You are feeding it DC try AC to sim it.
 
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You are feeding it DC. Try feeding it AC to sim it.
Your English is bad.

His 12V battery is in the wrong location and the circuit has no input signal so it has no output signal. Even the DC output voltage is wrong.
Also R5 is shorted.
 
oic, thank .... i want to ask , can i try the master circuit and slave circuit respectively by meansure the output voltage signal from speaker, without connecting both togather?
 
When you adjust the trimpots to null the local signal then there will be nearly nothing coming from your speaker when you speak into your microphone. The sound comes out of the distant speaker. That is how it avoids acoustical feedback howling where the mic hears the speaker and causes the sound to go around and around making feedback howling.
 
i was try the master circuit , measuring those part with Gnd, and the voltage i measured as list, i dunno why the base of transistor input so high , and the mike seem not worked....

and when i measure output 5 & 8 from the TDA7052a, the circuit became short circuit.... zero voltage measured....
 

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So why don't you measure at the slave circuit?

the circuit has been explained over and over several times.

You seem to have the wrong profession or the wrong hobby - possibly both.

Boncuk
 
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the problem is while i connecting speaker, the circuit became shorted, slave and master circuit also same.
 
Your transistor voltages are completely wrong.
Boncuk and you are using the wrong amplifier IC:
 

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ya , i know ... the base should be response only while i talking ... but i dunno why it maintain 6v++ and mike wasn't work
 
Your transistor voltages are completely wrong.
Boncuk and you are using the wrong amplifier IC:

I don't really see the reason why you pointed out the input coupling capacitor. The circuit contains it!

(C3 and C4).
 
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ya , i know ... the base should be response only while i talking ... but i dunno why it maintain 6v++ and mike wasn't work
The DC voltage at the base should be +6.0V, not +6.8V.
The voltage at the emitter should be about +5.3V, not +9.5V.
The voltage at the collector should be about +10.3V, not +6.0V.
Ground should be 0V, not +1.14V.
R7 should be 0V, not +0.6V.
Both outputs of the TDA7052 should be the same, probably +6.0V, not +1.0V and +10.6V.

The original circuit and Boncuk's circuit show the polarity of both C4 capacitors backwards.
 
I don't really see the reason why you pointed out the input coupling capacitor. The circuit contains it!
(C3 and C4).
I showed the original circuit's TDA7052 datasheet that has its pin 2 input grounded with a resistor. I also showed your circuit's TDA7052A with its pin 2 input grounded through the volume control but the datasheet shows a coupling capacitor maybe because it has DC on it. Maybe that is why the DC at the output of the TDA7052A is wrong.
 
the input to pin 2 of ic is +1.14V,
pin 2 of R7 should be 0V, not +0.6V.

and the speaker output not fixed at +1.0V and +10.6V, while i adjust the P1 , the value will different , either p1 max or min , voltage only +6V same

i will try TDA7052 IC at monday, see whether i connected speaker will get shorted circuit or not
 
May be wrong or not.

Comparing the data sheets of the TDA7052 and TDA7052A the only difference is the unconnected pin4 (DC volume control) in the TDA7052.

The internal connections should be same on both types.

Reducing the AF-input signal at pin 3 shouldn't have the effect of no speaker output.

I admit I didn't pay attention to the suffix "A", when I redesigned the circuit.
 
The datasheet for the TDA7052A does not have enough details and not enough spec's to show why its circuit uses an input coupling capacitor but the TDA7052 does not show an input coupling capacitor.

Maybe the input of the TDA7052A has a bias voltage that must be kept so it needs an input coupling capacitor. Then when the input is wrongly connected to ground through a resistor it might cause the outputs to have severe offset voltages. I don't use the lousy old TDA7052A because its datasheet is missing so many details. Instead I would use a TDA2822M amplifier in this circuit.
 
I think the TDA7052A will work properly if you add the 0.47uF input capacitor that is shown on its datasheet. Don't forget to correct the polarity of both C4 capacitors.

You do not use the stereo amplifier in figure 17 of the TDA2822M datasheet. You use the mono bridged amplifier circuit in figure 2 and its pcb design in figure 4.
 
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