# Operational Amplifier

**Types of Operational Amplifier**

**Inverting Amplifier:**

**Fig. :** Inverting amplifier

Voltage Gain,

**Non-Inverting Amplifier**

Voltage gain,

** **

**Fig. :** A non-inverting amplifier

**Voltage Follower**

: - for voltage follower

** **

**Fig. :** Voltage follower

**Summing Amplifier**

If*R*_{1}=*R*_{2}=*R*_{3}= R,

Then output voltage is given as :

** **

**Fig. : **Summing amplifier

**Differential Amplifier :**

V_{0}=

=

Put R_{1}= R_{3}& R_{4}= R_{2}

V_{out}=

**Fig. :** Differential amplifier

**Integrator:**As its name implies, the**Op-amp Integrator**is an operational amplifier circuit that performs the mathematical operation of**Integration.**

Ideal voltage output for theas:**OP-amp Integrator**

**Fig. :** Integrator

**Differentiator Amplifier:**The differentiator amplifier circuit performs the mathematical operation of**Differentiation.**

V_{o} = â€“R_{f }C

**Fig. : **Differentiator amplifier

IC-555 TIMER

**Fig. : **8-PIN DIP 555 timer

# IC-555 Timer as Astable Multivibrator

The time during which the capacitor charges from 1/3 V_{cc} to 2/3 V_{cc} is equal to the time the output is high and given by

t_{c} = 0.693 (R_{1} + R_{2}) C_{1}

Similarly the time during which the capacitor discharges from 2/3V_{cc} to 1/3V_{cc} is equal to the time the output is low and is given by t_{d} = 0.693 R_{2} C_{1}

Hence the total period of the output waveform is T = t_{c} + t_{d} = 0.693 (R_{1} + 2 R_{2}) C_{1}

**Fig. :** IC timer 555 in astable mode

**
Duty cycle. **The

*duty-cycle*is the ratio of time in the high state to the total period, T and is given by

**
Frequency of oscillation.** Frequency of oscillation is given by

**Fig. :** Voltage across capacitor C_{1} and output voltage waveforms

# IC-555 Timer as Monostable Multivibrator

The time during which output at pin 3 is high is given by t_{c} = 1.11 R_{1} C_{1} second

where C is in farad and R is in ohm. The equation clearly shows that width of the output pulse depends on the values of R_{1} and C_{1} only

**Fig. : **IC 555 in monostable mode

**Fig. : **Output waveforms