©2019 Robotics for COMPLETE Beginners

06

Potentiometers

 

Welcome to your lesson on potentiometers!

You are making great progress towards understanding the crucial fundamentals which will make building your electronics and robotics projects much faster and easier!

  

You will be rewarded for your patience and time! 

In the previous lesson you learned how push buttons work and how they help electricity to flow or prevent that flow.

In lesson 02 you learned what resistors are and how to interpret them.

If you need to head back and refresh your memory with a review of that lesson now.

Potentiometers function much like a resistor.  In fact they are called “variable resistors”.  Variable means they can change, so they can change how much they are resisting the flow of electricity.
 

Potentiometers are found everywhere.  You may have seen them as "dials".  Something you rotate to change a radio station, the volume of your music on a speaker or headset, your electric guitar, etc. 

They all generally look and function the same.  Here is what they look like. There are even slider types.  Notice most of them have a part you can twist with a screwdriver or coin.

Look around your room and spot a few right now.

Here is the schematic symbol, it is very similar to a resistor (because it is one) but has an additional arrow which means outside input. Your input, your twisting of the dial:

You can see in the first two pictures they have 3 metal leads or pins sticking out.  One of these connects to positive voltage and another to negative voltage and the middle pin is the analog output.  Analog just means real, not digital.

 

Think of digital as 1, 2, 3, 4...and analog as 1.125324, 1.243525, 1.4343224, 2.12325434, etc.  Analog is physical and digital is computer based.  Think of a digital watch vs an analog watch. The digital watch can only count whole numbers or fractions of whole numbers but the analog smoothly counts through every possible value as its arm moves in a circle.

VS

Digital

Analog

The current flows in through the potentiometer and out through the analog output pin.  When you turn the dial there is a wiper that increases and decreases the surface area that it comes in contact with a piece of resistive plastic.  More surface area that comes in contact increases the resistance which causes less voltage to come out of the analog output pin.

With a twist the amount of voltage being sent out on that output pin is changed. for example, there can be a minimum output voltage if twisted left and a maximum output voltage if twisted right. Simple!

 

That output voltage can control how bright an LED may get. It may be directed into a microcontroller which interprets that voltage and moves a servo or motor, or increases and decreases the rate LEDs blink. There are many, many uses for this simple amazing and cheap component.

To Ground

To Positve

If only there was a way to attach potentiometers to certain people, we could tune them down just a bit.

Pop Quiz

​1.  What is the typical pinout of a potentiometer?

2. Why are potentiometers also called "variable resistors"?

3.  How do potentiometers work with electronics?

4. What is the schematic symbol for a potentiometer?

Get my favorite books on programming AVR chips I use.

Equip yourself with the most dependable, no hassle, quality usb programmer I use daily.

Make sure you have a basic kit. Arduino is fine, it contains the removable AVR 328p chip we will use.

 

I started with something very similar.

Summary

You are already halfway through your journey to understanding what I consider the fundamental components which you will soon use to build great robots because you will understand what is happening.

You will be able to troubleshoot problems faster because you will be able to quickly figure out if there is a problem with your wiring, components or the code.

This is a great time to go back through the lessons and review each one even just 10 minutes each. Each time you review, you increase YOUR potential!  Thanks folks, I'll be here all night...possibly haunting you in your dreams...

As I always suggest, take some deep breaths, relax and write down what you have learned so far, it will surprise you!

See the parts in everyday items, think of how they work under their cases. Guess, investigate, be safe and have fun!

 

See you in the next lesson!