Amplified ear

[ImpulsE041993]

hello guys,

please help me how this circuit limits the highly amplitude signals from the mic.

the link below is the site i where i got the circuit.
https://www.redcircuits.com//Page38.htm

 

[colin55]

HOW THE CIRCUIT WORKS
The Hearing aid circuit above is a 3-stage arrangement, using transistors 1, 2 and 4. The third transistor discharges a 10u electrolytic when audio passes through the circuit and is not part of amplifying the signal.
We will concentrate on the operation of the third transistor.
The 10u is initially charged via the 100k resistor and the voltage on the 10u is passed to the base of the first transistor to provide maximum gain.
When audio is passed through the circuit, any waveforms above 0.6v are detected by the third transistor to turn it on briefly. This action partially discharges the 10u via the 1k5 resistor. The lower voltage on the 10u is passed to the first transistor to reduce its gain.
In this way, any loud signals are not amplified as much as weak signals and the circuit will pick up very faint sounds while it will not be overloaded by loud signals.
The output is connected to high-impedance (relatively high-impedance) earphones.

 

[4pyros]

When audio is passed through the circuit, any waveforms above 0.6v are detected by the third transistor to turn it on briefly. This action partially discharges the 10u via the 1k5 resistor. The lower voltage on the 10u is passed to the first transistor to reduce its gain.

Thay are controling the gain with the .6 volt threshold.

 

[ImpulsE041993]

i want to know the whole behavior of the circuit.. on how it operates.. and how every element in the circuit works..

 

[ImpulsE041993]

do u hav any idea?

 

[audioguru]

do u hav any idea?

We learned the basics and then advanced electronics so we know the function of each part of the simple circuit just by looking at it.

I don't know if somebody here has the time of a couple of years to teach you electronics.

 

[akolewl]

q

can you explain how the amplification process is done starting from the electret mic?
thanks.

 

[audioguru]

can you explain how the amplification process is done starting from the electret mic?
thanks.

You must learn the basics of electronics then learn how transistors work.

 

[gilmanli]

Yes,if you don't know basics electronics,it is very difficult talk with y

 

[akolewl]

thanks.. i have somehow understood the circuit already. but may i ask, what is the purpose of C5 and D1 in the circuit?

 

[colin55]

D1 discharges C3 and C5 prevents "motor-boating."

 

[akolewl]

thank you.