Figure 10 shows both frequencies superimposed together. It is observed that when one frequency is low, the other remains high. In other words, only one tone is generated at any point in time.
With these simulations, it can be inferred that the Ltspice results were as expected. Since these results align to what is known in theory, it is considered to be accurate. The prototype is only then built and tested with an oscilloscope. The results is recorded and shown in the figures below.
4.2 Oscilloscope Readings
Figure 11: Oscilloscope Waveform for A1
Figure 11 shows the square wave produced from A1. The frequency obtained was 1.14Hz.
Figure 12: Oscilloscope Waveform for A2
Figure 12 above shows A2 producing a frequency of…show more content… This can be seen by the two distinct waveforms occurring at separate times. Since these measurements tally with the Ltspice simulations, it clearly shows that the prototype is fully functional.
The slight difference in the frequency values could have been attributed from several factors. Simulations produce frequency values under perfect conditions. On the other hand, the practical approach is faced with imperfections such as noise, internal resistance from components and experimental inaccuracies. The group then proceeded to add three decoupling capacitors in attempt to improve the accuracy of the experiment.
4.2.1 Decoupling Capacitors
The decoupling capacitors were implemented with the intention to reduce the noise and fluctuations from Vcc. Unlike simulations, Vcc is not constant at 3V under practical settings. With reference to Capacitor Guide (2015), these capacitors act as a reservoir to provide the energy to keep the voltage stable. They help to oppose quick changes to the voltage since it takes time to charge and discharge. Three capacitors of values 120nF, 180nF and 220nF were used to decouple the input frequencies. The prototype is then tested using an oscilloscope and the results are shown below.
