Simple Potentiometer

Activity 2

Purpose

In this lesson participants will use the breadboard and the Arduino to create a simple circuit that will control the output of a light with a potentiometer. By the end of this lesson participants will understand what a potentiometer is, and the difference between analog and digital input.

Materials

For each participant:

3 wires
1 potentiometer
1 breadboard
1 Arduino Uno

In general:

1 Arduino USB cable to connect to computer
Computer source

Vocabulary

potentiometer
analog input
digital input
sensor
Arduino
Breadboard
LED

Step 1: Identity Activity

Ask the participants to review the pictures from the #ILookLikeAnEngineer twitter campaign.

Facilitate a discussion that asks the participants to reflect on what the pictures represent.

Provide students with the background information.

The hashtag campaign "I Look Like an Engineer" was created in August 2015 by software developer Isis Anchalee in order to challenge the stereotype of what an engineer looks like. She wanted to highlight how underrepresented groups, such as women and people of color, contribute and participate within the engineering industry. In response, many people from underrepresented groups shared photos of themselves with the #ILookLikeAnEngineer hashtag on social media platforms like Twitter, Facebook, and Instagram.

Discuss

Why do you think people felt compelled to participate and share their pictures?
Why do you think they decided to use social media as a tool for the campaign?
How else do you think people can challenge stereotypes of who participates in engineering?
~~Do you think you've participated in engineering practices?~~ What engineering practices do you think you have participated in?
- [Knowing how electricity works and understanding how to make circuits is a form of electrical engineering]

Step 2: Background On a potentiometer

Background

Arduino is able to work with both analog input and digital input. With a digital sensor, Arduino is able to read whether it is on or off. On the other hand, Arduino is able to read how much of something there is with an analogue sensor. This is great for working with sensors that have a range of settings and not just on/off, such as sensors that measure stretching, bending, force, heat, light, etc.

There are specific pins on the Arduino board that are able to read analog input. They are located in the bottom-right part of the board, and are marked "Analog In". These pins use the "analogRead( )" function in the Arduino code, which allows them to measure not only if there is a voltage applied to them, but the amount of voltage that is applied.

Arduino defines a potentiometer as "a simple knob that provides a variable resistance, which we can read into the Arduino board as an analog value". In this specific lesson, the potentiometer will control the rate at which the LED on the Arduino board will blink.

The potentiometer we will be working with looks like this. The knob on top can be twisted left and right. The three prongs will be inserted into the breadboard, fully incorporating the potentiometer into the circuit.

For More Background:

Electronics Basics - How a Potentiometer Works | Random Nerd TutorialsA potentiometer may come in a wide variety of shapes and are used in many applications in your daily life, for example to control the audio volume of the radio

This website here describes a potentiometer in more detail. Feel free to check it out, but this activity is very basic, and doesn't require the depth of understanding that the website goes into.

Step 3: Create The circuit

Directions

# 1

Insert the prongs of the potentiometer into the breaboard. It doesn't matter where the potentiometer goes, but ensure there is at least one row of empty holes next tothe side of the potentiometer that has the prongs. The wires will need to be connected into those holes to complete the circuit.

#2

Connect the first wire from ground to one of the outer pins of the potentiometer. The ground is labeled GND on the Arduino. It will be in the row of pins on the bottom part of the board, and is labeled "POWER" on the side, found right next to the "ANALOG IN" label. There are two GND pins, and it doesn't matter which of these two you put the wire into. For the outer pins of the potentiomenter, this means one of the holes on the breadboard that is next to one of the leftmost or rightmost potentiometer prongs.

#3

Next, place a second wire from the 5V pin to the other outer pin of the potentiometer. On the Arduino there should be a pin labeled "5V" right next to the leftmost GND.

#4

The last wire goes from analog input 2 to the middle pin of the potentiometer. Analog input 2 is labeled "A2" and is in the row of pins labeled "ANALOG IN".

#5

Following the directions for setting up the code on the main page:

Click on the "New Sketch" button found near the top-left of the page
Type the following code onto the new sketch. Make sure the code is identical, code must be exact. Include all semi-colons, dashes, tabs, and capital letters. If the code is not exact it will not run correctly.

I named my sketch "basic_potentiometer" but you are welcome to name it whatever you please
With the code you have on the computer click the " ✔"
Then click the "↠" circle, this will upload the code to the Arduino

Now you can try twisting the potentiometer. There is an LED built into the Arduino board that should be blinking. Based on the direction you twist the potentiometer, the blinking of the light will either speed up or slow down.

Step 4: REflection

In the first activity, we talked about how women used social media to share their identities as engineers. Have you ever used technology to share your identity with others? If so, how? What identities did you share? Why?
How would you describe a potentiometer to a friend?
What questions do you have about the arduino technology?
What skills from previous lessons did you use in this lesson?
What would you like to learn to do with arduino?

Appendix

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