Switches and LEDs ( PComp Lab 1 )


Introduction to Physical Computing / Week 2 / Switches and LEDs


My previous experiences in dealing with a circuit were not great. I had a few mandatory classes during my undergrad that dealt with electrical circuits and theory. However, being in a program that was trying to ‘focus’ on teaching software, the faculty as well as the labs were not good (they were bad and uninspiring). Personally, what this transpired into was an absolute befuddlement with how circuits worked, and barely getting through these courses with a minimum passing grade.

So yeah, there were some apprehensions as I was preparing myself to work on circuits. And to simply see that LED light up was magical. What felt better was to finally understand how a breadboard is structured, how the current flows into the wires, and how to deal with the anodes and cathodes. For the first time, I made a circuit without help or a grudge (haha).

I experimented with two kinds of switches. One was a basic switch, wherein connecting ends of a conducting wire would turn on the switch and holding them apart would turn the switch off. Very basic! A second switch was implemented using, well, a switch.

After this, as illustrated in the previous class, I played with a series circuit and a parallel circuit. The series circuit didn’t work the first time. The LEDs I was using worked with a higher voltage, apparently. So post-modifications, I had built a series circuit successfully. The parallel circuit was smooth.

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Shoelace switch:

shoe-lacesThe lab also asked us to think about a simple application for a switch and LED circuit. One useful application that I could think about was a shoelace switch. When the shoelace is taut, the current flows through one part of the circuit, hence lighting up a green LED. When the laces come undone, the current starts flowing through another segment of the circuit lighting up a red bulb. A simple circuit that could notify a person and prevent him/her from tripping over. Voila!

Below is a circuit diagram for such a circuit. There are two resistors and LEDs connected in parallel. The resistance for R1 is significantly lower than R2. Following the path of least resistance, the current across the green LED is high, and the current across the red LED is very low when the laces are tied together. I haven’t implemented the circuit yet, so I’m not sure if this will work. I’ll post a picture/video for a working model soon.

shoe-lace-switch

One thought on “Switches and LEDs ( PComp Lab 1 )

  1. This makes me so excited that you had a new beginning with electronics! And the shoe lace switch would be great to actually execute! You can make your own conductive shoe laces or there are some really close conductive fabrics you could use! Thank you for posting this.

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