Basic Electronics

I also attempted to create a switch in my circuit. The area where the threads cross to make an “x” serve this purpose. When the threads lay flat, the LED turns on. When one thread is lifted, the LED turns off. 

Series circuit: A series circuit is a type of circuit in which each component is lined up end-to-end to form a single pathway for electricity to flow. In this case, the threadboard circuit had LEDs, where the negative side of one LED would connect to the positive side of the next LED. 

At first, I tried to make the series circuit using a yellow and red LED. I knew from my experience in class that a single coin cell battery might not be enough to light multiple LEDs. Therefore, I stacked two batteries to increase the voltage. However, even with the correct configuration, the LEDs in my series circuit did not light up. After changing the LEDs, my circuit lit up. It is likely that the larger red and yellow LEDs required a higher voltage than the smaller white LEDs I replaced them with. 

Parallel circuit: A parallel circuit allows for electricity to flow through multiple pathways. In this case, multiple LEDs could connect to both the power and ground busses on the threadboard. 

Similarly to the series circuit, I tried to build the parallel circuit using the red and yellow LEDs. What was strange was that only the red LED lit up, and the yellow one didn’t. I suspect that the yellow LED requires more power than the red LED. When I replaced the colored LEDs with white ones, both white LEDs lit up. 

One thing I noticed between the series and parallel circuits was the difference in brightness for the LEDs. This was easier to see when I used the white ones. Generally speaking, the LEDs looked brighter in the parallel circuit than in the series circuit. When I compared one LED in the series circuit versus two, it was very noticeable that the two LEDs were dimmer. However, the brightness of one LED versus two LEDs in the parallel circuit looked very similar if not the same. 

Breadboard circuit: The breadboard circuit is built using a breadboard, a 9 volt DC power supply, and jumper wires. The DC power supply plugs into to a DC barrel jack, which is connected to a 7805 voltage regulator with jumper wires. The 7805 voltage regulator converts the 9 volts from the DC power supply to 5 volts. From there, the out voltage is wired to the positive column on the breadboard, and the ground is wired to the negative column on the breadboard. Since electricity runs through these two columns, I can run a connection from the positive column to the switch, to the resistor, to the LEDs, and then back to the negative column. Flipping on the switch will complete the circuit and turn on the LEDs. 

Series circuit: From the resistor, the LEDs are connected end-to-end, in which one path/wire connects back to ground. I used red LEDs, where the forward voltage is 2 volts, and the forward current is 0.02 amperes according to this website. Therefore, resistance would equal (5-2-2) volts / 0.02 amperes or 50 ohms. With this calculation, I chose a 47 ohm resistor for the series circuit. 

Parallel circuit: Both LEDs connect to the resistor to create two paths, which requires two wires to connect back to ground. I used the same red LEDs from the series circuit, so resistance would equal (5-2) volts / 0.02 amperes or 150 ohms. With this calculation, I chose a 100 ohm resistor for the parallel circuit.