please help ... what is the wrong in this circuit?

[electronics lover]

what is the wrong in this circuit?

 

[ericgibbs]

hi,
A quick look, it should work.
Its supposed to flash the LED's when the microphone gets an audio signal.

We need more info from you..what is the wrong in this circuit? dosnt help

 

[electronics lover]

hi,
A quick look, it should work.
Its supposed to flash the LED's when the microphone gets an audio signal.

We need more info from you..what is the wrong in this circuit? dosnt help

thank you Mr.ericgibbs , I connected the circuit but the LEDs are light in continuous shape .

 

[ericgibbs]

thank you Mr.ericgibbs , I connected the circuit but the LEDs are light in continuous shape .

hi,
Do these two quick tests.

1. Short the base of T3 to 0V, the LED's should off

2. Short the base of T4 to +9V, LED's should go off.

Let me know what you see.

 

[electronics lover]

hi,
Do these two quick tests.

1. Short the base of T3 to 0V, the LED's should off

2. Short the base of T4 to +9V, LED's should go off.

Let me know what you see.

hi ,

I have worked step 1 and 2 and the LEDs go off ,
Is the variable resistance RV1 and all transistors are true connected ?

 

[ericgibbs]

hi ,

I have worked step 1 and 2 and the LEDs go off ,
Is the variable resistance RV1 and all transistors are true connected ?

hi,
The last two tests suggest that T3 and T4 are not shorted.

The RV1 look OK
Look at these two images for the transistor pins, they agree with yours.

Disconnect C3 and check the LED's [then reconnect C3 after the test]
then
Disconnect C2 and check LED's

 

[mandalapurajesh]

i have some doubts....i dont know where to ask this..so any one plz help me...may be crazy doubts...plz help me....
1)why there in world only analog and digital signals ...is there any other signals?..plz clarify...?
2) what is input impedance?how it will come?
3) any electronic system have gain plot and phase plot...in that gain plots gives the information about staticts of the gain weather it improved or not...but coming to phase plot ..usaually we give inputs as analog signlas(mostly sine wave) with some phase and other stuff like amplitude etc..at the output of system... may the phase will increased or same or incresed...MAY BE my explanation was no so good....but i want know abt what is the use of phase plots and what is phase..?

 

[electronics lover]

hi,
The last two tests suggest that T3 and T4 are not shorted.

The RV1 look OK
Look at these two images for the transistor pins, they agree with yours.

Disconnect C3 and check the LED's [then reconnect C3 after the test]
then
Disconnect C2 and check LED's

hi ,
thank you Mr. ericgibbs
I have worked these steps , but the trouble is still .
the resistors R10, R11 and R12 I used are 920 K ohms , is this true or they must be 1 M ohm?

 

[ericgibbs]

hi ,
thank you Mr. ericgibbs
I have worked these steps , but the trouble is still .
the resistors R10, R11 and R12 I used are 920 K ohms , is this true or they must be 1 M ohm?

hi,
R10/11/12 are 1.5meg Ohms, using values lower than these could cause the problem you have.

 

[DerStrom8]

i have some doubts....i dont know where to ask this..so any one plz help me...may be crazy doubts...plz help me....
1)why there in world only analog and digital signals ...is there any other signals?..plz clarify...?
2) what is input impedance?how it will come?
3) any electronic system have gain plot and phase plot...in that gain plots gives the information about staticts of the gain weather it improved or not...but coming to phase plot ..usaually we give inputs as analog signlas(mostly sine wave) with some phase and other stuff like amplitude etc..at the output of system... may the phase will increased or same or incresed...MAY BE my explanation was no so good....but i want know abt what is the use of phase plots and what is phase..?

This thread is here to discuss Electronics Lover's circuit. I suggest you go back to the main page and under the "General Electronics Chat" click "Create new thread." I'm sure the members of this forum would be happy to help you out.
Good luck!
Der Strom

 

[audioguru]

The circuit is very sensitive. If it is built on a breadboard then the long connecting wires will pickup mains hum.
If the electret mic is not connected with shielded audio cable then its wires will pickup mains hum.

 

[electronics lover]

hi,
R10/11/12 are 1.5meg Ohms, using values lower than these could cause the problem you have.

hello Mr.ericgibbs , I have replaced these resistors by 1.5 M ohms , but the trouble is still .
I removed the resistor R11=1M ohm , and when I touch some parts of the circuit like T1 or T2 or some parts , the circuit Works well .

 

[electronics lover]

The circuit is very sensitive. If it is built on a breadboard then the long connecting wires will pickup mains hum.
If the electret mic is not connected with shielded audio cable then its wires will pickup mains hum.

thank you Mr.audioguru ,
but can you explain what this meaning "wires will pickup mains hum" ?
and can you get the picture for "shielded audio cable" ?
thanks.

 

[audioguru]

thank you Mr.audioguru ,
but can you explain what this meaning "wires will pickup mains hum" ?

If your home has AC electricity then its fairly high voltage sends "hum" all over the place. wires that are fairly long on electronic circuits that are built on a breadboard pickup the hum with the wires acting like antennas.

can you get the picture for "shielded audio cable"?

ALL audio input signals use shielded audio cable to avoid hum pickup.
A microphone has a very low level signal and a high gain preamp so its connecting wires must use shielded audio cable that is co-axial with a signal wire surrounded with shield wires.