The LED Party

As assigned, I played around with how electronic components can be rearranged to reach a desired effect. Using LEDs for visual output, I assembled several circuits to allow me to distinguish the differences between series and parallel wiring. I used a 12v (which unfortunately really outputs 16v) AC/DC transformer to power my bread boards after realizing that I was being a bit too careless with my Arduino as a power source. I created a small green light gradient using 3 LEDs connected in parallel to a potentiometer which controls the overall brightness of the circuit. I also created a simple circuit to toggle between two LEDs. While tinkering, I found a great site to help me calculate the resistance of any resistor graphically without having to memorize the color code

After playing with the different LED circuits for a while, I wondered if I could connect a capacitor into a given circuit to alter the way an LED turns on and off. Rather than a static binary state, I wanted to fade an LED on and off electronically. Luckily, I came across a circuit design which claimed to do just the trick. I took a quick trip to Radio Shack and did my best to find the parts required to build the circuit. As expected, The Shack didn’t have quite what I needed, but I did my best to substitute parts bases on their limited selection. My main concern was finding an operational amplifier which would serve to increase and decrease the voltage accordingly. I picked out the LM324 in place of the LM1458, and was a tad frustrated when after first building the circuit, nothing much happened. I decided to rebuild the circuit and paid closer attention to the resistances in the schematic. The original schematic also called for a 9v power supply, but the LM324 has a higher voltage rating than the LM1458 so I opted to used the voltage coming directly off the power adapter at around 16v. After reworking the circuit, I got it to work somewhat. The LEDs seemed to fade, but the effect was a bit too subtle. I played with the resistance and capacitance between the two op amps in the circuit to change the frequency at which the LEDs fade. Using a smaller capacitor and resistor increases the frequency, while a larger resistor and capacitor decrease the frequency. I found the cutoff resistance to be anything greater than 40K–causing the circuit to stop functioning properly. Check out the pictures and video below to get a sense of what I did. Until next time.

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