OpAmp multivibrators are fundamental circuits in electronics, capable of generating oscillatory outputs such as square waves. These circuits leverage the properties of operational amplifiers, resistors, capacitors, and feedback mechanisms to create stable, repetitive signals. This experiment focuses on constructing an OpAmp-based multivibrator to understand the principles of oscillation and the impact of variable components on the oscillatory frequency.

**Objective**

The goal of this experiment is to build an OpAmp multivibrator and explore how adjusting a potentiometer affects the circuit's oscillation frequency. By examining the relationship between component values and the resulting frequency, we aim to demonstrate the versatility and functionality of multivibrators in electronic design.

**Materials and Setup**

- Operational Amplifier (OpAmp)
- Resistors, including a potentiometer for variable resistance
- Capacitor
- Red Pitaya or equivalent for signal generation and measurement

**Circuit Assembly**

**Multivibrator Configuration:**Construct the OpAmp multivibrator circuit as depicted, incorporating a potentiometer to allow for adjustment of the oscillation frequency.

**Conducting the Experiment**

**Frequency Adjustment:**Utilize the potentiometer to vary the resistance in the circuit, observing the changes in oscillation frequency on an oscilloscope or equivalent measurement device.

**Analysis and Observations**

**Impact of the Potentiometer:**Adjusting the potentiometer alters the threshold voltage, thereby changing the time it takes for the RC filtered voltage to exceed this threshold and trigger a transition in the output.

**Relevant Equations**

The frequency of oscillation (*f*) and period (*T*) of the OpAmp multivibrator are determined by the feedback factor (*β*), resistance (*R*), and capacitance (*C*):

- Feedback factor: $\beta = R_1+R_2$
- Period of oscillation: $T = 2RC \cdot ln(\frac{1+\beta}{1-\beta})$
- Frequency of oscillation:

Additionally, the threshold voltage (*UTH*) for the inverting Schmitt trigger part of the circuit can be calculated using *β* and the saturation voltage +*Usat*):

- Threshold voltage:

**Conclusion**

This experiment with an OpAmp multivibrator illuminates the foundational principles behind oscillators in electronics, showing how simple adjustments to component values can significantly affect the circuit's output frequency. Through practical application and analysis, we've demonstrated the capability to create a basic, adjustable oscillator that produces a square wave output. Surprisingly, within this square wave lies the potential for sine wave extraction, hinting at the complex interplay between harmonic components in oscillatory signals. Understanding these principles offers a gateway to more advanced topics in signal processing and circuit design, revealing the inherent versatility of OpAmp circuits in generating a wide range of waveforms for various applications.