Object Lab 1: Basic Electronics

Part 1: LEDs in Series and Parallel

The first circuit for this lab consisted of two LEDs in series, with power supplied by a voltage regulator, which transformed 9v to 5v. Each LED had a forward voltage of 2v, and a minimum current of 30 mA. From this I derived a desired resistance of 33.33333 ohms. I choose the next strongest resistor available, which was 50 ohms.

The schematic for my completed circuit is below.

The second circuit involved the same power regulator and LEDs, but this time involved two LEDs run parallel, with a resistor in each parallel piece of the circuit. For this circuit, I calculated an ideal resistance of 100 ohms per resistor.

Below is my diagram of the second circuit, as well as my implementation.

Part 2: DIY Switch

For my custom switch, first I folded copper foil around two patch cables. Next, I cut out a picture frame shaped piece of foam and glued it to one of the cable, as seen below.

Next, I glued the other foil wrapped cable to the other side of the foam. Finally, I cut squares of foam to protect the outsides of the switch from grounding issues and shorts. A diagram of the switch can be seen below.

The idea behind this switch is that when the two sides of the foam are squeezed together, the copper sheets will connect and complete the circuit, making a sort of instantaneous switch. Videos of the switch functioning can be seen in part 3.

Part 3: Creative Enclosure

At first, I planned to make an enclosure for my board out of corrugated cardboard. Given the relative weakness of my fabrication skills though, I soon decided that I would be better served to find a pre made box that would fit my electronics. After trying a few boxes which ended up too big, I finally happened across an empty cigarette package which turned out to be a perfect size. I chose this as the basis for my enclosure.

Since my electronics were very limited in their function, and could really only turn a lightbulb off and on, I decided that I would take advantage of this simplicity to “animate” an illustration. In order to do this I would move the electronics into the enclosure, and place an image on top of the box so that it would be illuminated when the LEDs were switched on.

First, I moved replaced the toggle switch with my custom switch, and tested for errors. After brief troubleshooting, everything worked, and I moved the breadboard into the box. To prevent random malfunctions, I taped several of my leads, and cut holes of the 9V supply. I taped the LEDs to the top of the box. Below is a video of the open enclosure, with functioning electronics.

After making sure everything was functioning and secure, I closed the box, and taped it so it would stay closed. To do this, it was necessary to route the button of the box and back in, as seen above. Below is the closed box, with the illustration attached.

Finally, time for the final test: will the cat’s eyes light up?

They did!