SIGNAL AMPLIFIER
1. ABSTRACT:
The circuit shows a 3-transistor
voltage amplifier suitable for a variety of projects including receivers,
intercoms, microphones, telephone pick-up coils, and general audio monitoring.
The values are not particularly critical and modest deviations from the
indicated values will not significantly degrade the performance.
2. COMPONENTS:
·
Resistors
·
Capacitors
·
Transistors(Q2N2222)
·
Voltage
Supply(DC)
·
Input
Voltage(Vsin)
3. WORK OF EACH COMPONENT:
·
Resistors:
In the
given circuit resistor R5 is working as an Rs. It is also used to improve
amplifier. R6 and R7 have such a high resistance values, so that whole current
which is coming from source go to the base of the Q2. R10 and R11 also have
high resistance values for same reason. R12 is Rc(collector resistance) of Q3
and R13 is Re(emitting resistance) of Q4. R14 is load resistance.
·
Capacitors:
Capacitors
are used for pass the AC current and block the DC current. C5, C6 and C8 are
working to prevent the ac current to directly hit the DC supply.
·
Transistors:
All the
3 npn transistors work to amplify and stabilize the input signal.
·
Voltage Supply(DC):
Dc
supply is given to put all the Transistors into cut-off region.
·
Input Voltage(Vsin):
To give the minute input sinusoidal signal.
4. CIRCUIT DIAGRAM:
5. WORKING OF CIRCUIT DIAGRAM:
A minute sinusoidal wave is given to Q2 which
is brought into cut-off region by Vdc and hence amplifies the signal. The
signal then is carried forth to the next pair of transistors which stabilize,
modulate and further amplify the signal the output at the emitter of Q4 is fed
to C9 which across the R14 is the final output.
6. OUTPUT RESPONSE:
Red: Input
Green: Output
7. APPLICATION:
Voltage amplifiers can be used in various fields. Among them some are given
below:
· Receivers
· Intercoms
· Microphones
· Telephone pick-up coils
· Mobile phones
·
General audio monitoring
