31th JAN - The First Lab - Research & Simulation

On the first week, we mainly did two things including searching relevant circuit information on the internet and simulating the waveform using Multisim. Finally, we decided using following circuit diagram to connect our circuit.

figure 1

For simulation part, we tested every part respectively and using sine wave as input signal.The frequency and amplitude were adjusted to 1 KHz and 4V. We found that the first amplifier on the left hand side is used to amplify the signal which shows in figure 2.

figure 2

The red line represents the output waveform of the first amplifier and green line represents the input waveform. The second amplifier on the left hand side is used to clip and amplify the signal that was amplified by the first amplifier which shows in figure 3.

figure 3

The green line represents output signal of the first amplifier and red line represents output signal of the second amplifier. 

figure 4

After passing through the third amplifier, the waveform nearly become a DC signal but it is not stable which is shown in figure 4 that there is some glitches on the purple line. After passing through the last amplifier, it is much more stable which is at -19.6V which is shown in figure 4 by blue line.

For second week, we will check the operating voltage of PIR Sensor before and if it is within the normal range we will connect the circuit in the lab and replace the function generator by PIR sensor. According to the simulation results of the first week, it is much easier to check the real circuit. If output signal corresponds to our simulation, we will check the following part: sensitive angle, sensitive distance,etc.