Formula Sheet: Function Generator & 555 Timer | Analog Circuits - Electronics and Communication Engineering (ECE) PDF Download

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Analog Circuits: F unction Generator & 555 Timer
F orm ula Sheet for GA TE
F unction Generator
• Purp ose : Generates w a v eforms (sine, square, triangular) with adjustable frequency
and amplitude.
• Key Comp onen ts :
– Oscillator (e.g., Wien Bri dge for sine w a v es).
– W a v e-shaping circuits (e.g., in tegrator for triangular w a v es, Sc hmitt trigger for
square w a v es).
• Wien Bridge Oscillator F requency :
f =
1
2pRC
where R is resistance (? ), C is capacitance (F ).
• Condition for Oscillation : Gain of the amplifier m ust b e =3 for sustained oscilla-
tions.
555 T imer
• Purp ose : V ersatile IC used as a timer, oscillator, or pulse generator in astable and
monostable mo des.
• Pin Configuration :
– Pin 1: Ground, Pin 2: T rigger, Pin 3: Output, Pin 4: Reset.
– Pin 5: Con trol V oltage, Pin 6: Threshold, Pin 7: Disc harge, Pin 8: V cc.
555 T imer: Astable Mo de
• Op eration : Generates con tin uous square w a v e (oscillator).
• F requency of Oscillation :
f =
1.44
(R
1
+2R
2
)C
(Units: Hz )
where R
1
, R
2
are resistors (? ), C is capacitor (F ).
• Time P erio d :
T =
1
f
=0.693(R
1
+2R
2
)C (Units: s )
• Dut y Cycle :
Dut y Cycle=
R
1
+R
2
R
1
+2R
2
×100% (cannot ac hiev e e xactly 50%)
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Analog Circuits: F unction Generator & 555 Timer
F orm ula Sheet for GA TE
F unction Generator
• Purp ose : Generates w a v eforms (sine, square, triangular) with adjustable frequency
and amplitude.
• Key Comp onen ts :
– Oscillator (e.g., Wien Bri dge for sine w a v es).
– W a v e-shaping circuits (e.g., in tegrator for triangular w a v es, Sc hmitt trigger for
square w a v es).
• Wien Bridge Oscillator F requency :
f =
1
2pRC
where R is resistance (? ), C is capacitance (F ).
• Condition for Oscillation : Gain of the amplifier m ust b e =3 for sustained oscilla-
tions.
555 T imer
• Purp ose : V ersatile IC used as a timer, oscillator, or pulse generator in astable and
monostable mo des.
• Pin Configuration :
– Pin 1: Ground, Pin 2: T rigger, Pin 3: Output, Pin 4: Reset.
– Pin 5: Con trol V oltage, Pin 6: Threshold, Pin 7: Disc harge, Pin 8: V cc.
555 T imer: Astable Mo de
• Op eration : Generates con tin uous square w a v e (oscillator).
• F requency of Oscillation :
f =
1.44
(R
1
+2R
2
)C
(Units: Hz )
where R
1
, R
2
are resistors (? ), C is capacitor (F ).
• Time P erio d :
T =
1
f
=0.693(R
1
+2R
2
)C (Units: s )
• Dut y Cycle :
Dut y Cycle=
R
1
+R
2
R
1
+2R
2
×100% (cannot ac hiev e e xactly 50%)
1
• High Time (T
on
) :
T
on
=0.693(R
1
+R
2
)C
• Lo w Time (T
off
) :
T
off
=0.693R
2
C
555 Timer: Monostable Mo de
• Op eration : Generates a single pulse of fixed duration when triggered.
• Pulse Width (Time Duration) :
T =1.1RC (Units: s )
where R is resistance (? ), C is capacitance (F ).
Key Notes
• T ypical Supply V oltage : V cc = 5V to 15V for 555 Timer.
• Capacitor Charging/Disc harging : Based on R C time constan t, t = RC .
• Con trol V oltage (Pin 5) : Used to mo dulate frequency or pulse width (t ypically
b ypassed with 0.01 µF capacitor).
• GA TE Tips :
– Memorize astable and monos table form ulas.
– Chec k units: resistances in ? , capacitances in F , time i n s , frequency in Hz .
– F or astable mo de, dut y cycle < 50% requires additional circuitry (e.g., dio de
across R
2
).
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