In this experiment, the circuit has three subsystems with many electronic components. The first one played as an automatic switch to run the circuit. The second subsystem was a manual switch for the circuit. Finally, the last subsystem has been used to increase the current that flows through the circuit. In this section, the three subsystems will be described individually:
1. Subsystem #1
The first subsystem (Figure 1) has been used as an automatic switch. For this circuit, three main components have been used, which are a Trim Pot (Figure 2), a LDR (Figure 3) and an operational amplifier (LM324) (Figure 4). The Trim Pot is a small potentiometer that can be used for adjustment in a circuit. Also, the Trim Pot can be used as a variable resistor (preset resistor). The LDR (light dependent resistor) is a light-controlled variable resistor. The resistance of the LDR increases when the incident light intensity decreases, that means the LDR is proportional to the incident light intensity. The Trim Pot (Variable resistor) and the LDR are connected the operational amplifier (LM324) that passes the current when the LDR has a higher voltage. In this subsystem, an LED has been used as an indicator when the current flows through the operational amplifier (LM324).