How to use a Breadboard!

Used by hobbyists and professional engineers alike, breadboards allow us to quickly build all sorts of circuits!

Breadboards got their name because in a time long ago, engineers used to use wooden cutting boards! They would hammer in nails and wrap wires to make connections. Not only was it tedious, but the cooks got frustrated that their breadboards kept getting stolen and used for definitely-non-food-purposes, so eventually someone invented the plastic breadboard to keep kitchen utensils safe. Hooray!

Similar to wires, plastic breadboards use conductive metal and insulating plastic to create paths where electricity can flow (the metal parts), and breaks where it cannot flow (the plastic parts).

If we were to look underneath a breadboard and peel off the backing, we would see something like this:

What do you notice?

The middle of the breadboard is different than the outsides. On outside of the breadboard, on both the left and the right sides, there are two long strips of metal. These are called “Power Rails”, or “Power Buses”, and one of the strips by itself is called a “Power Bus.”

Flipping the breadboard back over, the top, where we make our circuit connections, looks like this:

Looking at our Power Buses, there are colored lines next to them. While these are just guidelines (ahhhh sorry for the terrible pun, lol), the colored lines are super helpful for keeping track of how we connect our battery or power supply to the breadboard. Typically blue means negative, or ground (“gnd”), and red means positive.

The middle gap of the breadboard is called the trench. This separates the two identical middle halves of the breadboard. The trench is sized so that components with more than 3 pins can fit across.

The rows of the breadboard are marked with numbers, in this case numbers 1 – 30. The columns are marked with letters A, B, C, D, and E. Each row has a set of 5 holes that are connected by the piece of metal we saw on the bottom, as well as metal pins on the inside that hold wires and component pins in place. Some of the hole groups that are electrically connected are shown on the photo above with red rectangles.

Now let’s make some circuits! We’ll need four (male-to-male) jumper wires and the following parts:

Next, we’ll connect the battery to the power rails. If your battery case does not plug directly into the breadboard, grab two jumper wires for this.

The battery case that you are using might change how you connect your battery to the circuit, and that’s okay! The important part is that you connect the positive side of teh battery to one power bus, and the negative side of the battery to the other. Be sure that both sides of the battery are in different power buses (if you feel the battery getting warm it may indicate that it is short-circuited, this would be the place to double check).

Next, let’s connect our light! Grab your remaining jumper wires and your LED.

Insert the LED legs so that both legs are in two different rows (reminder: rows are marked with numbers). Connect the positive side of the battery to the longer LED leg. Connect the negative side of the battery to the shorter LED leg.

Voila! If the LED is connected to the battery in a circuit, it will light up!

Try moving your LED to a different part of the breadboard. Observe what happens!

Does wire color matter? Try two different colored wires and see what happens!

Finally, let’s end our exploration by tracing the path of the electricity.

Electric current is defined to flow from positive to negative. That means our electric current, which is made up of moving charges, flows out of the positive side of the battery, through the wire and into the breadboard power bus. It flows through the power bus, then up and out the red wire to the breadboard row where it can travel up the LED where it does work (and loses some energy) to make the LED turn on.

Then the (less energetic) electric current flows out of the LED through the shorter leg, into the breadboard row where it flows into the black wire. It then flows out of the black wire and into the second power bus, through the power bus and back to the negative side of the battery.

Our circuit is a circle! The moving charges that leave their home must also come back, but they come back more tired and into the back-door (which is to say, the negative side!).

Other helpful terms:

  • Current: The amount of charge flowing past a point in our circuit.
    • Current units are given in Amperes/Amps, or A
  • Voltage: The potential energy, or pushing force, across a component in our circuit. A higher voltage means more pushing force.
    • Voltage units are given in Volts, or V.
  • Resistance: How much a particular component resists the flow of electricity.
    • Resistance units are given in Ohms, or O
  • Capacitance: How much current a battery can provide over time.
    • Capacitance units are given in Amp-hours, or Ah.

There are two ways to connect components:

1. In series: connect components in line with one another, or head-to-tail.

2. In parallel: connect components in loops, or head-to-head.

Going Further!

You are now ready to tackle more circuits! Try adding more lights, or using different components. What happens when you add different kinds of components together? How many ways can you combine multiple components ?What sorts of projects could you use these circuits for? Share your creations with us, we always love to see and share!

And of course, please let us know if you have any questions, we are here to help!

Other useful tutorials:

Happy making!

A Beginner’s Guide to Microcontrollers

What do remote controllers, routers, and robots all have in common? Microcontrollers! These days, beginner-friendly microcontrollers are easy to build with and program using just a laptop, a USB cable, and some (free) open-source software. The catch? There are like, 4324302* different microcontrollers and it can be daunting to get started, especially if you’re just getting into electronics. Where the heck do you start?!

Right here, bbies, I got chu. Whether you are looking to build some cool electronic projects, learn programming/tech, or wanting to teach others about electronics, this tutorial will help you figure out what microcontroller is right for your needs, goals, and budgets. Yay! Let’s get started!

Read Time: ~ 20 min

*Ok, ok, maybe not *that* many, but definitely a few dozen!


Wait…What is a microcontroller??

Maybe you’ve seen this word and were like “uhhh..?” but didn’t feel comfy enough to ask*. Totally fine, here’s a quick rundown:

A microcontroller is a “simple computer” that runs one program in a loop. They are designed to perform a single, specific task.

In this guide, we’ll be focusing on microcontrollers that have breakout boards, or a board that makes it easier to connect to and program the microcontroller.

On a breakout board, the microcontroller pins are soldered to a printed circuit board (“PCB”), headers or other connectors are added to the PCB, and some basic firmware, or permanent software, is loaded to prep the microcontroller to receive signals.

*Questions are always good even if they are “dumb” or “n00by”, just find a safe space — like this site or Instructables!

What’s the Difference Between the Raspberry Pi and a Microcontroller?

The Raspberry Pi is not only small and adorable, it is also a full-fledged computer! 😀

Computers have microprocessors AND microcontrollers that work together to perform many tasks at once.

The microprocessor is what does the “heavy lifting” in a computer. It performs the instructions and calculations that make the computer work. Microprocessors are much faster than microcontrollers, but they need external resources like RAM, Input/Output ports, etc., whereas a microcontroller is typically self-contained.

Computers (which are microprocessors) can run multiple programs at a time — you can surf the Internet, reminisce with old photos, write a paper, and have like 1000 tabs open all at the same time! Microcontrollers… not so much. You can do one of those things, but not all.

To learn more about the Raspberry Pi, check out the last section of this tutorial!

Arduino (Uno)

A robust, open-source microcontroller and programming environment designed for beginners with some knowledge of circuits.

Recommended Ages: 12+ (or kids comfy with programming and algebra)

Difficulty: Intermediate

Average Cost: ~$35

There are lots of different types of Arduino boards. This is the Arduino Uno, the best fit for beginners! There are boards that are larger, smaller, wearable, and for specialty use cases like robotics.

Being familiar with Arduino boards and programming maps well to projects and careers in computer science, engineering, and design.

Hardware Features

  • The Arduino Uno has 14 Digital Input & Output (“I/O”) pins, 6 Analog I/O pins, 2 Power Out pins (3.3V and 5V), and 3 Ground (GND) pins.
  • Power input can be anywhere from 5 to 12 VDC
  • The ICSP header (right side in both photos) allows you to connect a ton of different add-on boards called “shields”.
    • For example, you can add a WiFi shield to connect your Arduino to the ‘net!

Example Project: 

Robot Mini Golf Obstacles

Motion-Reactive Shake the Maze Game!

Purchase/Learn More: Arduino Website (


A friendly lil’ microcontroller handy for kids and folks just getting started with coding and hardware.

Recommended Ages: 8+ (or kids comfy with circuits and simple tools)

Difficulty: Beginner

Average Cost: ~$15

The Micro:Bit is a great tool to start learning how to code, teaching others, particularly elementary school students, how to code, and making simple and quick electronic prototypes.

The Micro:Bit is a collaboration between Microsoft and the BBC to bring educational computers into classrooms around the world.

Hardware Features:

  • The Micro:Bit has 3 Digital and Analog I/O pins, 1 Power Out pin (3.3V), and 1 Ground (GND) pin
  • Power input should be 3 – 5 VDC via micro USB cable or battery pack connector.
  • It also has lots of onboard inputs, outputs, and sensors!
    • 5×5 (25) LED matrix
    • Two (2) Pushbuttons (A, B)
    • Radio Transmitter and Receiver
    • Accelerometer
    • Compass
    • Light and Temperature Sensors
  • For more I/O pins, grab a Micro:Bit breakout!

Example Project: 

Text Messenger Puppet!

Purchase/Learn MoreMicro:Bit Website

Circuit Playground Express

A versatile microcontroller great for kids and folks just getting started with coding and hardware.

Note: There is also the Circuit Playground Classic — the hardware is nearly identical, but this board is programmed in the Arduino IDE.

Recommended Ages: 8+ (or kids comfy with circuits and simple tools)

Difficulty: Beginner

Average Cost: ~$25

The Circuit Playground Express, or CPX, is a helpful tool to learn how to code, teach others how to code, and make quick prototypes for beginners to experts alike.

The Circuit Playground Express is a powerful and versatile microcontroller created by Adafruit Industries.

Hardware Features

  • The CPX has 7 Digital/Analog Input & Output (“I/O”) rings that are also capacitive touch!
    • 1 “true” Analog I/O ring
    • 2 Power out ring (3.3V)
    • 3 Ground (GND) pins
  • Power input should be 3 – 5 VDC via micro USB cable or battery pack connector.
  • There are also tons of onboard inputs, outputs, and sensors!
    • 10 Mini Neopixels (can be all colors)
    • 2 Pushbuttons (A, B)
    • 1 Slide Switch
    • Infrared Transmitter and Receiver
      • Can receive/transmit remote control codes, send message between CPXs, and act as a distance sensor
    • Accelerometer
    • Sound sensor and mini speaker
    • Light and Temperature Sensors

Example Project:

 Minecraft Gesture Controller!

Purchase/Learn More: Adafruit Industries

Makey Makey

An interactive introductory microcontroller great for young kids and folks new to electronics and coding, especially for those who want to play with technology without having to build circuits and code.

Recommended Ages: 5+ (or kids comfy with simple tools)

Difficulty: Beginner

Average Cost: ~$50

The Makey Makey is a great first step into electronics and technology — no programming required! Connect alligator clips to the pads and then connect any somewhat conductive material, like hands, fruit, or metal objects, to trigger certain keyboard and mouse keys.

The Makey Makey is an Arduino-compatible board, meaning that you can also reprogram it using the Arduino Integrated Development Environment (“IDE”).

Hardware Features

  • The Makey Makey has six (6) capacitive touch pads on the front of the board:
    • Four control the keyboard arrow keys,
    • One controls the spacebar, and
    • One controls the left mouse click.
  • On the back of the board are header pins for more controls (also capacitive touch):
    • Six (6) pins that map to letters,
    • Four (4) pins that map to arrows,
    • Two (2) pins that map to mouse keys, and
    • One (1) pin that maps to the spacebar key.
    • There are also three (3) general I/O pins, a 5V power pin, and a ground pin.

Example Projects

Beginner: Floor Piano

Intermediate: Interactive Survey Game!

Purchase/Learn More: Makey Makey website

Other Common Boards

There are waaaay too many microcontrollers to cover in one tutorial. If you have a super specific specialty need, there is probably a microcontroller for that (just like apps!). To get a feel for some of the other boards not mentioned in this tutorial, peruse the inventories of SparkFun Electronics and Adafruit Industries and/or ask folks in the field!

Here are a few of my favs:

Particle Photon

Similar to the Arduino Nano, the Photon is a WiFi connected microcontroller that can be programmed wirelessly. The easiest setup uses a (free) smartphone app, but if can also be programmed directly via USB in almost the same language as Arduino*.

Recommended Ages: 12+ (or kids comfy w/ circuits and coding)

Difficulty: Intermediate

Cost: ~$20

For more info and to get the Photon setup, visit the Particle online store here.

Example Project

IoT Industrial Scale

*Wiring is the code framework, so most Arduino code will work without modifications. Can also write in C/C++ or ARM assembly

Adafruit HUZZAH ESP8266 Breakout

A super small, super cheap (and currently very popular in the IoT* community) WiFi microcontroller. You’ll need an FTDI or console cable. You can use the Arduino IDE to program this board or NodeMCU’s Lua Interpreter.

Recommended Ages: 14+ (or kids comfy w/ hardware & software)

Difficulty: Intermediate++

Cost: ~$10

For more info, visit the HUZZAH Adafruit product page.

(SparkFun also has a similar board, the “ESP8266 Thing”, which you can find here for ~$15.)

*IoT stands for “Internet of Things”, which is the term that refers to connecting and controlling various hardware devices, like sensors and household electronics, to the Internet.

Adafruit Trinket M0

A teeny tiny yet powerful microcontroller that blurs the lines between computer and microcontroller (it has an ATSAMD21E18 32-bit Cortex M0 processor). It can be programmed with Circuit Python or in the Arudino IDE.

Recommended Ages: 14+ (or kids comfy w/ hardware & software)

Difficulty: Intermediate

Cost: ~$9

For more info, visit the Adafruit product page for the Trinket M0.

There are a TON of other M0 boards, similar in scope to the Arduino Zero connectable microcontrollers. If this doesn’t suit your needs or your fancy, search around on the Adafruit and SparkFun websites!

Wearable Microcontrollers

There are also a handful of microcontrollers designed for wearable projects!

What makes these special is that they can be washed, so you don’t have to rip them out of the awesome project you made (but do remove the battery!).

Wearable microcontrollers also have special I/O pins that make it easier to sew into clothing and stitch circuits with conductive thread. Here are a few of my favs:

Adafruit FLORA

A circular sewable microcontroller with 14 inputs and outputs. Can be washed (but def remove the battery).

Recommended Ages: 12+ (or kids comfy w/ circuits and coding)

Difficulty: Intermediate

Cost: $15

For more information, visit the Adafruit FLORA product page.

Arduino Gemma

A lil’ tiny sewable microcontroller with 3 inputs and outputs. Perfect for hiding, connecting to small objects, and creating jewelry.

Recommended Ages: 12+

Difficulty: Intermediate

Cost: ~$5

For more information, visit the Arduino Gemma product page.

Arduino Lilypad

A circular sewable microcontroller with 14 available inputs and outputs.

Recommended Ages: 12+

Difficulty: Intermediate

Cost: ~$25

For more information, visit the SparkFun product page for the Lilypad.


Raspberry Pi 3

The Raspberry Pi, or Pi for short, is a credit-card sized computer* that runs a special version of Linux and can be programmed to control hardware.

Recommended Ages: 12+
Or kids comfy with coding and algebra

Difficulty: Intermediate (easy as a computer)

Average Cost: ~$35

The Raspberry Pi computer, or Pi for short, can be used as a “standard” computer or as a controller for all sorts of hardware projects. It is a great first computer for kids to use and learn to code on, and is widely used by hardware experts to build all sorts of electronic projects, from robots to 3D printers to home automation systems!

The Raspberry Pi has changed the way we build electronics! There are a few different versions, the most recent is the Raspberry Pi 3 and the Pi Zero, a miniature version of the Pi 3 for just $10.

Hardware Overview

  • The recommended Operating System (“OS”) is a special version of Linux called Raspbian.
  • The Pi has 40 General Purpose Input and Output (“GPIO”) pins.
    • 26 Digital I/O pins (no Analog I/O)
    • 4 Power Out pins (two 3.3V and two 5V)
    • 8 Ground (GND) pins
    • 2 Specialty Pins (I2C ID EEPROM, advanced use only)
  • The Pi also has most standard computer features:
    • 4 USB Ports
    • 1 Ethernet port
    • 1 HDMI port
    • 1 Audio Jack
    • 1 Camera Module Port

Example Projects

Local Cloud Server

IoT Pet Monitor! (Raspberry Pi Zero)

Impact Force Monitor

Purchase/More InfoRaspberry Pi Foundation

*The Pi can be used similar to a standard microcontroller AND can also control microcontrollers! Basically, the Pi is super awesome and I *have* to include it even tho it is technically a computer 🙂

Final Thoughts

If you are just getting started and want to build all sorts of projects, I’d recommend the Circuit Playground Express. It’s super easy to get up and running and has a ton of onboard gadgets.

If you are super interested in computer networking, AI, or connecting things to the Internet (e.g. making a “Smart Home”), I’d suggest the Raspberry Pi.

If you want a sturdy, stable, and reliable board to build a wide variety of projects, go with an Arduino.

If you still have no idea where to start and are totally intimidated, start with the Micro:Bit — it’s only $15 and has plenty of snazzy things on it to play with. Plus, if you get one for your friend, you can send lil’ messages back and forth 🙂

The best advice I can give you is to find a project you are passionate about and build it! There are tons of tutorials online so search around for someone who has built the same or similar project. Build off of their findings and adjust as you please!

And of course, leave any related questions in the comments and I’ll do my best to help!

Happy hacking!

Intro to the (Headless) Raspberry Pi!

Finally! Use your Raspberry Pi without spending what feels like forever connecting external peripherals and dealing w/ a cable monstrosity: Configure your Pi to be headless! (not the scary kind tho) This is particularly helpful for folks teaching workshops with the Raspberry Pi, since it can be cumbersome (and expensive) to provide monitors, keyboards, and mice for every student.

I’m assuming that y’all know a bit about the Pi, so this tutorial will not cover what the Pi is or it’s awesome capabilities (I’m lookin’ at you, GPIO pins!). To learn more about what the Pi can do, check out some of my other tutorials (see the last section in this tutorial) or leave a comment.

What is covered in this tutorial: Enabling and using SSH, a general overview of the Linux terminal window, and how to connect to the Pi’s GUI (Graphical User Interface, aka the Desktop view) via SSH.

Read Time: 15 min

Build Time: ~20 min

Cost: Free! (assuming you already have an RPi and Ethernet cable)


Computer with Ethernet port & SD Card slot

– Raspberry Pi 3

– SD Card (8GB or larger)

– MicroUSB to USB power cord

– Ethernet Cable

– RecommendedRaspberry Pi Case & GPIO cable


For this project, you’ll need the following (free!) software programs:


Configure the SD Card

1. Download your favorite flavor of Raspbian! You can get the most recent version here.

2. Insert your SD card and open Etcher.

3. Select the Raspbian zip file, the driver for your SD card, and click “format”.

4. Enable SSH access

Open the file contents for the SD card. Add a new text file titled “SSH”. If the computer adds a file extension (e.g. “.txt”), delete it and ignore any warnings.

5. Eject the SD card and insert it into your Pi.


Let’s Get Connected!

1. Plug in the Ethernet cable between the Raspberry Pi & your computer.

2. Plug in the USB power cable.

Check that the red power light turns on and that the Ethernet port lights (yellow & green) are on and/or blinking.

3. Connect the RPi to the World Wide Web (aka the Internet).

Go to Settings -> Network & Internet -> Change Adapter Options (aka Network Connections).

Click on the Ethernet connection, hold down “CTRL”, and then click on your WiFi connection.* Right-click in the window and select “Bridge Connections” — this will bridge the connection between the Ethernet port to your WiFi port.

*If you select the WiFi connection first, it will bridge the connection from the WiFi to the Ethernet, which would allow you to log into the Pi but not connect to the Internet.

4. Open PuTTY and log in to the Pi using the “raspberrypi.local” IP address.

Default username: pi

Default password: raspberry

5. Change the default password by typing passwd and following the prompts.


Navigating the Linux Terminal Window (Shell)

The terminal window is the control panel for the system.

It typically shows a command prompt, which gives us information but is not part of the commands to the system. Most commonly the command prompt displays the user’s login name and the current working directory (represented by a twiddle: ~ ).

Inputting Commands

Commands are written after the prompt and inputted by pressing the Enter key.

Commands can be issued as-is or followed by one or more options. Options usually have a dash in front of them, like the following:

ls -a

You can view the options for a specific command by typing the command name followed by “–help” (will cover this more later).









Linux Hot Keys!

There are a handful of special key combinations that make navigating the terminal window easier and faster. Here are a some of the most common ones:

  • Ctrl+A – Move cursor to beginning of command line
  • Ctrl+E – Move cursor to end of command line
  • Ctrl+C – End running program
  • Ctrl+D – Logout of current session
  • Ctrl+R – Search command history
  • Ctrl+Z – Suspend a program


  • Left and Right arrow keys – Move cursor one place to the left or right on command line
  • Up and Down arrow keys – Browse command history
  • Shift+PageUp and Shift+PageDown – Browse terminal buffer (to see text that is off screen)
  • Tab – Command or filename completion
  • Tab Tab – Shows file or command completion options

Practice using these every time you are in the terminal window and you’ll quickly become a Linux wizard!

Getting Help in the Terminal

1. Manual and Information Pages

The manual pages are an exhaustive resource for all of the available commands in the Linux terminal window. To read the manual pages on a particular command, type the following:

man command

This will pull up the manual pages for the particular command that you are searching. Here’s the manual pages for the apropos command:

In the manual, the first line contains the name of the command you are reading about and the ID of the section that contains the manual page.

After the first line is a synopsis, which is a short description of the command that includes technical notation of all the options and/or arguments. Options are a way of executing the command, and an argument is what you execute it on. Optional arguments are put between square brackets.

After the synopsis is a longer description of the command, followed by a more in-depth overview of the available options, information about combining options, other related commands, and other information pertaining to the command.

Some commands have multiple man pages, like the “passwd” command. To see all pages about a command, use the “-a” option:

man -a passwd

The info pages contain more recent information and can be easier to use. Here’s what the menu of the info pages looks like:

To view the info pages on a command (replacing “command” with the actual name of the command you want to research, like “apropos”), type the following:

info command

To navigate the info pages, use the arrow keys to browse through text, the Enter key to read about a particular keyword, “P” and “N” keys to go to the previous or next subject, and the space bar to move one page further. Use “Q” to quit.

2. whatis and apropos commands

The whatis command gives brief information about a command and lists the first section in the man pages that contains a relevant page (in parenthesis after the command name).

If you’re entirely unsure where to start, the apropos command is a good way to search for keywords. For example, if you want to know how to start a browser, you can type apropos browser, which will pull up a list of all browser-related programs, including web browsers, file and FTP browsers, etc.

Here’s the apropos search results for “text”, which displays commands and programs that contain the phrase “text”:


3. Using the –help option

Most commands also have the option –help, which gives a short explanation of the command and a list of available options. When in doubt, this is a great way to get some quick and useful information on using a particular command and its possible extensions.

To use the –help option, type –help after a particular command, like the following example (also shown in the photo above):

apropos --help

The output looks like this:


Enough of the Terminal Window! Where’s the friggin’ Desktop??

Alright alright.. Remote Desktop Connection is an easy way to use the desktop view, also known as “Graphical User Interface,” or GUI for short.

1. Install Remote Desktop Connection on your Pi:

sudo apt-get install xrdp

2. Install Remote Desktop Connection on your PC (is already installed on Windows OS).

3. Open Remote Desktop Connection and log in using the “raspberrypi.local” IP (or find your Pi’s IP using command ifconfig). Ignore warning (click “yes”).

4. Log in with the Pi’s username and password.

If you haven’t changed your password yet, do so now. (Yes, I know I already told ya to do so but it is worth repeating since someone could actually hack into your Pi if you don’t change the default password.)

Now you can use the Pi’s GUI and do almost* everything via your PC!

*Sadly, we can’t play Minecraft in this mode as it uses too much data to be transferred via SSH. Using a VNC viewer is one option around this if you really want to play Minecraft remotely.

What is SSH, anyway?

SSH stands for “Secure SHell” — it is a “cryptographic network protocol for operating network services securely over an unsecured network.” – Wikipedia

… Uh, what?

In other words, SSH is a secure way to connect between one computer and another, even if the network through which you are connected is not secure.

For example, if you are on a shared network and you use SSH to remotely log into another computer, other folks on the shared network can’t see what you’re doing through the remote connection (although Snowden did release documents that showed the NSA can sometimes decrypt SSH).

Common uses of SSH include remote log in, like if you want to connect to a computer that lives a mile underground without having to, you know, actually go down there. (I used to work for a super cool dark matter experiment called DRIFT and this is how we would access the computers that controlled the detector because the computers lived in a mine about 3 miles underground.. too far to travel to update software!).

Here’s the full Wikipedia page on SSH — it’s super cool so check it out!

More to Explore!

Go forth and explore! Practice using the terminal window until you get comfortable and familiar with the basic commands.

Program the GPIO pins to do cool stuff! Need some ideas? Check out these tutorials:

1. Making a Soil Moisture Sensor

2. Building an Irrigation Controller (can be paried w/ Soil Moisture Sensor)

3. Bark Back: Install an IoT Pet Monitor

4. Expand on your Smart Home & add a Motion Triggered Music Player

Need parts?

Take apart old & broken electronics! Electronic toys are a great place to get motors and speakers. If you want better motors, take apart power tools.

Ask friends or find a repair shop for extra parts and wire, save power cables from old electronics and use them as power supplies or harvest them for wires and/or connectors, save old headphones and use them for audio projects.

Best piece of advice: think before you toss 🙂


Renewable Energy Technology: What is it and How to Use it!

Now more than ever, folks like you and me have to step up and take a stand to protect and preserve our environment (and, quite honestly, our species). One great way to do that is to incorporate renewable energy technology into projects that use electricity.

Even if the environmental aspect isn’t enough to get you on board, you should still use renewable energy tech because the simple truth is that eventually we will run out of coal and natural gas. Besides, renewable energy tech is cleaner and more cost-effective in the long term, AND it means that you rely less on external sources for electricity — super handy in case there’s a severe storm or a solar flare that temporarily knocks out your local power grid.

First of all, what is renewable energy technology? Basically, it encompasses any technology that generates (electrical) energy from effectively renewable sources. For example, from our perspective, the sun is essentially an infinite power source since it will be around long after we are gone and produces more energy than we could possibly hope to consume in our lifetime.

Coal and natural gas are NOT renewable because they are finite, meaning that there is only so much of it available for us to use. Once we’ve used it up, we’re pretty much sh** out of luck, as the saying goes.

Now that I’ve convinced you it’s a good idea to use renewable energy technology, what are your options and how do you actually go about incorporating them into your projects?? Well my friend, read on to find out! This is by no means an exhaustive list, but it does cover the most common and easily accessible types of renewable energy tech.

Also, this guide assumes you have a basic knowledge of electronics, so please ask if there is a term or concept that you’re unsure about and I’ll be happy to expand or provide you with more thorough resources. Happy building!!

Photovoltaic Panels (aka Solar Panels)

Solar panels are awesome! I put these first because they are one of the most common and, in my opinion, the easiest to incorporate into all kinds of different electronic projects.

How Solar Panels Work

Solar panels convert incident radiation (aka sunlight) into usable electrical energy via the photoelectric effect. Basically, a photon (light carrier particle) knocks into an electron and transfers its energy to the electron. By making solar panels out of special materials called semi-conductors, one with extra electrons and one with missing electrons (aka “holes”), the free electrons are attracted towards the positively charged material (and repelled by the negatively charged material). When an external load is connected across the solar panel, it creates an effective current.

Since the current output depends on the amount of sunlight hitting the panel, the highest power output occurs when the panel is in full, direct sunlight (and is free of dust and debris).

How to Use a Solar Panel

  1. First, solar panels output Direct Current (“DC”), which is ideal for computer/microcontroller projects. For household applications, you’ll need an inverter to convert the DC voltage into AC.
  2. Second, since we’ll only get energy generation during the day, we’ll (most likely) need to use a rechargeable battery to store the energy for use at all hours of the day and night. Calculate the battery capacity that you’ll need by multiplying the electric current consumption of your project by the number of hours it will be on and consuming power without any external charge. For example, if my project consumes 0.20 mA of current and I want it to be able to provide power all night (~ 12 hours), I’ll need a battery with a minimum capacity of: 0.20mA * 12 hours = 0.0024 Ah (2.4 mAh). Also, the battery voltage needs to be lower than the solar panel voltage for current to flow from the panel into the battery.
  3. Third, use a diode for trickle charging or a charge controller for higher power applications to protect the solar panel from backwards current flow.
  4. Finally, to choose the right sized panel, figure out how much power your project consumes (P = I * V) and pick a panel within a reasonable range. For example, the power consumption of a 5V, 0.50mA microcontroller is 0.0025 W, so a panel between 1W and ~ 7W would be more than sufficient. For larger power panels, be sure you have sufficient circuit protection to avoid blowing out your microcontroller or other electronic device(s).

For more information, here is a helpful guide.

Wind & Water Turbines

Wind and water turbines use pretty much the same mechanism to generate electrical energy, so I lumped ’em together. Of course, depending on what medium you’re using, you’ll want a different turbine size and shape.

How Turbines Work

Turbines are a mechanical device that rotate when an external fluid passes through the blades of the turbine, whether it’s water or wind (whoa what air is a fluid?! yes, yes it is :D). The turbine is connected to a drive shaft that spins an electric generator to produce electrical energy. 

How to Use Turbines

  1. Turbines are location dependent, so first you’ll want to figure out if it’s feasible: Do you have a stream, waterfall, or other moving water source nearby? Does the location of your project get steady wind?
  2. Turbines also output DC current, so you’ll need an inverter for household appliances.
  3. As with solar panels, you will likely want a rechargeable battery to store the power for use anytime during the day or night, regardless of weather conditions. Calculate your needed battery capacity using the same method as for solar panels.
  4. Use a diode for low-power projects and a charge controller for larger projects to protect the energy generator from backwards current flow.
  5. Determine the power output for your turbine by calculating the power consumption of your project in the same way that’s outlined for the solar panel.

There are tons of DIY wind turbine projects on the interwebs, including on Instructables! Find one that fits your project needs and try building your own!! 😀

Here’s a link to more information on wind turbines!


Thermoelectric Generator

Thermoelectric generators (“TEGs”) are super cool, but generally have a very low power output. That said, they are not weather dependent, don’t have any moving parts (aka are essentially maintenance free), and are very reliable. Thermoelectric generators can be super handy for small projects like charging smartphones or powering LEDs.

How Thermoelectric Generators Work

Ok, so these things are somewhat complicated — basically, special materials with high electrical conductivity and low thermal conductivity can generate an electric current when there is a temperature gradient (aka a temperature difference between one side and the other). So if you heat one side of the thermoelectric generator and cool the other side, a current will flow. It also works the other way around — if you apply a current to the generator leads, it will cause one side to heat up and the other side to cool down.

A super simple thermoelectric generator is shown in the photo above: a junction of two different metals (copper and iron) is heated to produce a current output between one end of the copper wire and the head of the nail. It’s too little current to be of much practical use, but it’s a great educational project!

How to Use Thermoelectric Generators

  1. Another DC electrical energy generator! Get at those inverters for AC power applications.
  2. Since these are super low power, I’d suggest a rechargeable battery just like with solar panels and turbines, and maybe even an amplifier like a transistor.
  3. Since these will likely stay low power, you shouldn’t need a diode to protect the TEG, but be sure to have adequate circuit protection for your particular electronic load.
  4. You can purchase TEGs that have specific power outputs, typically for camping purposes, or you can rig up your own using peltier junctions. Consider connecting a few in series to get a higher energy output.

Here’s a great overview on how TEGs work, check it out and be inspired!


Other Types of Renewable (& Clean) Energy Technology

Ok, so that’s it! We’ve covered 3 of the primary renewable (and clean) energy technologies! There are TONS more out there but they are either 1) super involved, 2) super expensive or 3) both. Here are two of the more common ones to give you a sense of what is possible in the wonderful world of renewable energy technology!

Geothermal Power Plants

Geothermal power plants use hot water deep in the earth to run a steam turbine. This requires ridiculously deep wells (~ 1km) to pump up the hot water, run it through a heat exchanger (or directly through a steam turbine if you’re lucky enough to be close to a water source that hot), and then push the water back into the earth or let it seep back down naturally.

These are super cool because there are no negative consequences of energy generation — no pollution is generated (only steam!), no water is lost, and it the water will heat back up naturally over time.

Nuclear Power Plants

These are a bit controversial due to the radioactive waste byproducts of nuclear fission, but nuclear power plants do in fact generate renewable, clean energy. As long as the waste is properly stored and there are safeguards in place to prevent meltdowns, nuclear power plants are relatively safe and well understood.

Currently, nuclear power plants use the process of fission, which involves breaking up an unstable atom (e.g. uranium) to get out high energy electromagnetic radiation (aka light). That energy is usually converted into heat and used to run a steam turbine.

Ideally, we’ll figure out fusion somewhere in the near future, which is the process of fusing two simple atoms together (usually two isotopes of hydrogen). Nuclear fusion generates electromagnetic energy and inert particles like helium. This is what stars do! Except they are much, much more efficient as they are insanely hot and high pressure.

Fusion does NOT produce any radioactive waste, so it would be a perfect solution to our energy crisis. Now to just figure out how to get a net positive energy output….

For more info on fusion, check out this awesome article by the folks at Industrial Quick Search Directory.

Go Forth & Build!

Now you know what renewable energy technology is and, generally speaking, how to incorporate it into your personal projects. It’s also a great way to charge your gadgets while out and about, make your projects portable, and have a backup power source in the event of a power outage.

Please feel free to ask any and all questions! My goal with this is to empower you to feel confident in using some sort of renewable energy tech in your everyday life, whether you purchase it or build your own.

Remember, it’s ok (and encouraged) to start small and simple! Use a solar panel to power a small motor, use a wind turbine on your bike helmet to power a bike light, or use a thermoelectric generator to light up some LEDs while camping!

If this tutorial inspires you, I’d love to see any projects you made, share ’em in the comments below!!

How to Use (and Choose) a Multimeter!

Checking your car battery life, debugging circuits, and finding that pesky short are all super useful functions that can be performed with just one awesome tool: the multimeter!

First of all, what the heck is a multimeter??   Excellent setup question! It’s a handheld device with bunch of different electrical meters — hence, multi-meter!

Measuring voltage, current, resistance, and continuity (aka electrical connection) are the most common uses of a multimeter.  Read on to learn what this means, how to do it yourself, and how to choose your very own multimeter!

Choosing a Multimeter!

There are a few key differences between multimeters, the main one being analog versus digital:
Analog multimeters show real-time changes in voltage and current, but can be difficult to read and log data.

Digital Multimeters are easier to read, but may take some time to stabilize.

There are also auto-ranging multimeters, that automatically detect the measurement range, and manual ranging multimeters where you have to choose a range yourself (or start with the highest setting and work down).

Other than those two main differences, you’ll want a multimeter that has separate ports for current and voltage measurements (this is a safety issue, both for the meter and for yourself).

Next comes the fun part: features! Multimeters all have voltage and current meters (otherwise they’d just be called voltmeters and ammeters!), and most can also measure resistance. There are a variety of other “extra” features depending on manufacturer and cost (e.g. continuity, capacitance, frequency, etc.).

Second-to-lastly, there are a ton of different types of probe leads, including alligator clips, IC hooks, and test probes. Can’t decide? Here’s a kit that has four different types!

Lastly, always check the multimeter maximum voltage and current ratings to be sure that it can handle what you want to use it for.

Using a Multimeter!

But first! A quick overview of voltage, current and resistance!

My favorite analogy for electricity is the “water flowing through a pipe” analogy. In this analogy, voltage is similar to the water pressure, current is like the water flow (except with current you have electrons instead of water molecules!), and resistance is akin to the size of the pipe. Check out this tutorial for an awesome and thorough overview of electricity.

Keeping these analogies in mind helps us to figure out how, and what, we are measuring.

Measuring Voltage:

A voltage measurement tells us the electrical potential, or pressure, across a particular component.

Voltage is basically the “oomph” in our circuit, s so we want to avoid drawing any power from the circuit when we take a voltage measurement. This means we need to measure voltage in parallel with a particular component using infinite (or really, really high) resistance to prevent any electrical current from flowing into the meter.

Using a multimeter to measure voltage across a component (or battery!):

1. The black multimeter probe goes into the COM port, and the red probe into the port marked with a “V”.

2. Switch the dial to the “voltage” setting (choose the highest setting if you have a manual ranging multimeter).

3. Place black probe on negative side of the component, and red probe on positive side (across, or in parallel with the component). If you get a negative reading, switch the leads (or just note the magnitude of the voltage reading).

Read the meter output and you’re done! Not too bad 🙂

Measuring Current:

Taking a current measurement tells us the amount of electricity flowing through a given component or part of a circuit.

To measure current, we need to measure all of the flow in our circuit without consuming any power from the circuit and reducing the current measurement. This means we measure current in series with a component and we want our meter to have zero resistance.

Using a multimeter to measure current through a component:

1. The black multimeter probe goes into the COM port, and the red probe into the port marked with an “I” or an “A” (or “Amp”).

2. Switch dial to the current setting (choose highest setting if you have a manual ranging multimeter).

3. Connect red probe to current source, and black probe to the input of the component, so that the current flows from the source, through the meter, to the component (in series with the component).

Read the meter output! If you’re not getting a reading, switch to a lower setting.

Measuring Resistance: 

Measuring resistance is pretty straightforward, but you do have to disconnect individual components from a circuit to get their actual resistance, otherwise the rest of the components in the circuit can interfere with your measurement.

Using the multimeter to measure resistance of a component:

1. Put the black probe in COM port, and red probe in the port marked with a “Ω” or “Ohm” — it should be the same port as the voltage port.

2.  Switch dial to setting marked with a “Ω” (may have to choose approximate range for manual ranging multimeter).

3. Place probes on either side of the component (orientation doesn’t matter).

Read the meter output and you have conquered resistance!

Bonus: Measure Continuity!

The continuity measurement checks if two points in a circuit are electrically connected, otherwise known as a conductance test. Before measuring continuity, be sure that the circuit power is OFF.

Using the multimeter to measure continuity: 

1. Place black probe in COM port, and red probe in voltage port.

2. Switch dial to setting marked with an audio symbol.

3. Place probes at points you want to check — if the meter makes a beep sound, it means the two points are connected.

Le fin!

Go forth and measure all the things!

Now that we know how to use a multimeter, get crackin’ on all those at home, DIY projects! To get you started, here are a few quick, practical, & fun projects:

1. Measure the resistance of your skin! Change the distance of the probe leads and see how resistance changes. Lick your fingers (or dip them in water) to see how moisture affects resistance!

2. Measure the voltage across AA, 9V, or other batteries around the house/workplace/school to locate dead, or dying, ones.

3. Make a lemon battery and measure the voltage and current output.

4. Use the continuity setting to check if different materials conduct electricity.


Looking for more info on multimeters?

Check out this in-depth guide by the folks at Tools Critic!

Using an Oscilloscope!

Visualize all those mysterious electronic signals with an oscilloscope!

Learn how to build and use a super simple $30 oscilloscope perfect for electronics hobbyist applications. It’s also a great way to get started using some of the fancier oscilloscopes!

Reading and Changing the Oscilloscope Display

Every oscilloscope has a window that displays the voltage output of your signal. On every display, the y-axis is voltage, and the x-axis is time.

You can zoom in and out of the display grid by adjusting the “Volts per division”* or “Seconds per division”.

On this oscilloscope, the voltage adjustment switches are on the left side (bottom two switches), and they let you zoom out to as much as 5 Volts (“V”) per division, and zoom in to 10 mV per division.

Adjust the time scale using the “+” and “-” buttons on the right side.**

*”Per division” means the size of the squares, e.g. 1V per division means that each square is 1V in height, 1 second per division means that each square is 1 second wide. 

** Be sure that the time scale is selected (will be highlighted with a box around it — this is the default selected setting, change settings using the “sel” button, described in more detail in the next section.

Other Basic Features 

This oscilloscope has all the expected features of larger, more expensive ‘scopes, and also is a great introduction to some of the more complex versions.

On the left side, the top switch allows you to choose between a ground signal, a DC signal, and an AC signal. On the right side of the oscilloscope are four buttons:

1. The “ok” button (very top button): Pushing it once takes a snapshot of the screen, which can be saved to the oscilloscope. Holding this button down displays key numeric values about your signal, like the maximum and minimum voltage, signal frequency, etc.

2. The “+” button: Similar to an up arrow key, pushing this button allows you to sort through options.

3. The “-” button: Same as the + button, but, you know, scrolls down

4. The “Sel” button: Pushing this button allows you to select different features (described in order):

A. Change the time scale.

B. Set how the oscilloscope display refreshes – “Auto”, “Norm,” or “Sing”. More on these in the next section.

C. Set the trigger slope. More on this in the next section.

D. Change the trigger level. More on this in the next section.

E. Adjust the horizontal position of the oscilloscope display.

F. Change the vertical position of the display.


Oscilloscope Trigger

Oscilloscope triggers cause the oscilloscope to display a signal. Triggers are set at a specific value, or “trigger level,” along a specified direction, or “trigger slope” (more info below).

The trigger helps to display the exact electrical signal that you want, so that you get a stable display and measurement. In this ‘scope, the trigger is set on the right side of the display and the LED at the bottom flashes when the trigger is detected.

The simple oscilloscope in this tutorial has three trigger modes that you can switch between using the “+” and “-” buttons:

  1.  Automatic (“Auto”): Display continually refreshes, regardless if triggers are met.
  2.  Normal (“Norm”): Display only refreshes if the trigger is met.
  3.  Single (“Sing”): Same as normal mode, waveform display is held after a trigger has been detected.

More on Trigger Level and Trigger Slope!

The Trigger Level is a set, internal voltage that is compared to the signal, or input, voltage. The oscilloscope triggers when the signal voltage is equal to the trigger voltage. If an electronic signal rises and falls, then the trigger would happen twice: once when the signal is rising and again when the signal is falling. The trigger slope lets you choose which voltage (rising or falling) to trigger on.


Connecting a Component!

Now, to see the electrical signals at work in the world around you, connect the black lead to ground, and the red lead to the part of the circuit that you want to measure the voltage.


For example, if you want to measure the voltage output of a sensor, like the capacitor in the photo to the right, you want to connect the red probe after the sensor.


You may also want to calibrate your scope using the on-board signal. See the datasheet for more info.


Finally! Turning on the DSO138 Oscilloscope

The an oscilloscope kit in this tutorial takes about 2 -3 hours to assemble (instructions here), but is definitely worth it because many reasons! Here are a few: It’s a great way to learn circuit components, get familiar with schematics, and practice soldering (and de-soldering….). And, honestly, it’s pretty relaxing.

Once you’ve got the ‘scope assembled, it needs 9V and about 0.1A. There are two power ports: a barrel jack and a male JST connector. You can use a 9V battery with the barrel jack (OMG it’s portable!), or a power supply with the JST connector.

The exposed wire on the top of the oscilloscope is a square wave signal to help you calibrate the signal (see the datasheet for more info).

Be sure to use less than 12V or you risk heating up the board and possibly damaging it (don’t let the black smoke out!).


Plug and Play!

Now you know all the basics to connect your oscilloscope to sensors, your tongue, and other low power sources to watch the wonderful world of electricity at work!

Please leave a comment in the tutorial if you have any questions or would like more info about the oscilloscope kit. Now go forth and explore all that electricity! 😀

Interested in building a capacitive touch sensor like the one used in this tutorial? Check out this tutorial!


Portable Solar USB Charger

Portable USB chargers are incredibly useful for adventures in the great outdoors, festivals, traveling, or if you are out-and-about all day. Adding in a solar panel provides an additional source of portable power useable (nearly) everywhere.
The whole project can be built for ~ $20, even if you don’t have a soldering iron!


  • 1.5W Solar Panel 9V
    • Suggested to use a low-power solar panel, typically if you are not using a charge controller.  
    • Note that the solar panel voltage output MUST be higher than the battery output for it to actually charge
  • 1N914 or similar diode
    • This protects the solar panel by allowing current to flow only from the panel to the batteries (aka prevents discharge from the batteries onto the solar panel).
    • If you choose a similar diode, be sure it works w/ the given solar panel specs (voltage/current output).
  • USB car charger
  • Rechargeable 9 V battery**
  • Battery holder for 9V (or use alligator clips)
  • Project container (e.g. tupperwear, altoids tin, cookie tin, etc.). Be creative!


  • Wire strippers
    • Scissors also work. To strip the wire, make cuts on both sides and pull off insulation w/ your fingers.
  • Electrical Tape
  • 5-minute epoxy, or other similar adhesive (gorilla glue probably works)
    • Other methods for making electrical connections: twist wires together and coat in epoxy. Other connections can be MacGyvered together; take apart old electronics for connectors and wires, use paperclips, and be creative w/ conductive objects like pennies.
  • Multimeter, if available. Massively helpful for testing electrical connections and checking if the circuit works as expected.

Background Info

Solar panels are awesome for many reasons:

  1. Renewable energy technology, woo!
  2. Handy in remote locations (like Burning Man..).
  3. Lifetime of 25 – 30 years.

Solar panels, or photovoltaic (PV) panels, output direct current (DC). Digital devices, like cellphones or iPods, run on DC. This means our charging circuit is fairly simple. As in the photo on the left, we need a panel, a battery, and our device, or load. Charge controllers regulate current flow primarily to protect the battery. We can avoid using one in our USB charger, but they are ideal for larger systems.

The solar charging system works w/out the batteries. The batteries are there so you can use the system whenever you need it.


A lil’ bit about USBUSB_pinout

As shown in the photo to the right, USB chargers have 4 pins. All USB chargers output 5 Volts (V) DC on the USB Vcc pin. However, the amount of output current depends on the type of USB charger. There are three main types: a standard downstream port (500 mA), a charging downstream port (1500 mA), and a dedicated charging port (900 mA).

Apple USB is a bit trickier (unsurprisingly..); one of the data pins is set to 2.7 VDC. So, if you finish your portable USB charger and you want to charge an iPhone or iPod, you need to increase the voltage (aka use a bigger battery.. or two 9V batteries connected together in series.

Build ProcessSolar_USB_Charger

Note: if you are using the epoxy method for connecting wires, wait until after you’ve tested the whole system to coat w/ epoxy..  epoxy is rather permanent and once it is set there is little you can do besides curse at it (won’t really help, but might make you feel better!).

  1. Strip wire on end of solar panel (remove colored insulation to expose the metal).IMG_4626

    No leads on the panel and there’s no soldering iron?! It’s all good! Get creative.
    Here’s one way: tape two wires onto the metal pads on the back of the panel w/ electrical tape (colors don’t really matter, but convention is red = positive and black = negative). Test it w/ a multimeter, or by connecting the leads to the USB car charger to make the “charging” LED light turn on. Coat in epoxy, let dry & you’re done!
  2. Connect diode to positive end of solar panel lead. If possible, solder the two ends together. Otherwise, twist wires & coat in epoxy at the end. Super important: install the diode so that the side w/ the silver band is connected to the battery, like in the photo to the right.
  3. Connect diode to positive (red) side of battery holder. Connect negative (black) solar panel lead to negative battery holder lead.IMG_4643
  4. The front metal part of the USB car charger is the positive terminal. One of the metal side tabs is the negative terminal. Determine which side of the USB car charger is the negative (or ground) side.
    Here are a couple easy ways:
    — Open up the charger; see which metal tab is connected to a wire.
    — Use the panel to turn on the charger. Connect the positive battery/solar panel lead to the front metal lead. Touch the negative battery/solar panel lead to each side. The side that causes the “on” light to light up is the negative side.
  5. Connect the negative battery/solar panel lead to the negative tab on the USB car charger. Connect the positive battery/solar panel lead to the front metal lead on the USB car charger.
    There are a few ways to do this, depending on your available tools and materials. The easiest way is to use alligator clips (and coat them in epoxy when it’s all done & tested).
  6. Test it! Connect a USB device (like the Raspberry Pi!!) and make sure it lights up.
    If it works, epoxy all the electrical connections, put it into a container and take it w/ you on an adventure!
    Once your first version works, make upgrades and modifications as necessary! Google is super helpful.


*More info about solar!

Solar panels have a relatively low energy efficiency rating, typically around 12-15%. Research is continually improving solar efficiency, and a lab in Germany set the world record for solar cell efficiency at 44.7%.

In 2012, average costs of solar per watt were between $1 – $2, with some as low as $0.70 per watt. Although this does not include the cost of additional equipment (e.g. batteries, transformer for AC applications, mounting system, etc.), it is beginning to seriously compete with fossil fuels. Yay, solar!!

**Why a 9 V battery?

USB car chargers expect 12 VDC from the car, but will accept between 6 VDC and 14.5 VDC. Using a single 9V battery is the easiest way to get a sufficient input voltage for this USB circuit in order to get an output of 5 VDC.

Blinking Light(s) with the Raspberry Pi!

Welcome to the wonderful world of controlling physical objects with software! This tutorial is a complete beginners introduction to the Raspberry Pi computer, covering the basic features and functions to help you bring your ideas to life!


Blinking a light using the Raspberry Pi’s General Purpose Input and Output (“GPIO”) pins is the hardware equivalent of a “Hello World” software program.

  1. First, gather the following materials:
    Breadboard (or wires/alligator clips)
    Two (2) Breadboard wires (Male-to-female are ideal)
    One (1) (or more!) LED (Light Emitting Diode)
    One (1) 330 Ohm resistor
    And the rest of the normal stuff to set up the RPi (SD card, power cord, keyboard + mouse (or just keyboard), HDMI cable and monitor.)
  2. Wire up the breadboard!IMG_4146
    Pick a GPIO pin. Attach the female end of one breadboard wire to the GPIO pin, and the male end
    Connect the other breadboard wire from ground on the RPi (third down on exterior side) to negative slot on the breadboard.
    Connect the resistor from the positive series of holes to an open row on the breadboard (I picked row 10).Connect the long side of the LED to the same row the resistor is in. Connect the short side to the negative slot.
    Make sure nothing explodes (just kidding that probably won’t happen 🙂 )
  3. Write a quick Python program.
    The program switches the GPIO pin between on and off, turning the LED on/off as it switches. Save the program somewhere easy, like the Desktop.
    Here’s my code if you need some assistance:

    import RPi.GPIO as gpio
    import time

    #SEtup pin 18 as an output
    gpio.setup(18, gpio.OUT),/span>

    #define data to be the value of pin 18
    #data = GPIO.IN0(18)

    #Make an LED flash on and off
    while True:
    gpio.output(18, gpio.HIGH)
    print(‘Light is on.’) #Optional printout of status
    time.sleep(1) #changing the number increases/decreases length of signal
    gpio.output(18, gpio.LOW)
    print(‘Light is off.’) #Optional printout of status

  4. Run the program!

IMG_4144In the terminal window, go to the folder where you saved your program. The command cd + the directory name (ex. /home/pi/Desktop) will take you there.
Run the program by typing sudo python “ProgramTitle”.py
As long as everything is connected and the program does what you think it does, the LED will flash.
That’s it! Super simple, and it means that this little RPi computer just controlled a physical object wooooo!!!
Optional fun:
– Change the timing of the blink.
– Connect a couple more LEDs the same way you connected the first (these will be in parallel with each other).
– Connect additional GPIO pins to more LEDs and change the timing (remember to also add in the appropriate code).

Helpful info:

As shown in the photo to the right, breadboards usually have columns for positive and negative (red and black, respectively) that are connected electrically all the way down the board.  Each row contains 5 holes that are also connected.

The resistor needs to go in between the LED and the power source to limit the amount of current, or electricity, flowing through the LED. The LED would be brighter w/out the resistor, but it will probably burn up super quick.

Happy building!


Setting up a Raspberry Pi to Control Physical Objects, Pt. 2

What cool things can you do with the Raspberry Pi?


Welcome back to exploring the Raspberry Pi! There are tons of awesome things you can do with the Raspberry Pi — (pretty much) everything that you would do on a normal computer, like word processing, surfing the internet, streaming videos, etc.

You can write programs on it using the Idle software (Python language), Scratch, or Linux. This might seem mundane, but keep in mind that you bought this lil’ computer for only $30 dollars (+shipping and handling). If you have kids, this is a fantastic option for a first computer! The RPi naturally teaches and encourages hardware and software programming. Plus, you won’t mind as much when the kids spill apple juice all over it (or if you’re like me and still spill apple juice on computers, this is a great option for a backup computer..).


You can print this GPIO Leaf and stick in on the board!
You can print this GPIO Leaf and stick in on the board!

GPIO Pins!
By far the coolest way to use the Pi is to interface w/ the real world using the GPIO pins (that row of 26 pins adjacent to the RCA video port, or the yellow port). The GPIO pins have different functions as shown in the photo below: 17 of the 26 total pins are actual GPIO pins, while the rest are either ground, a power source (5 VDC or 3.3 VDC) or labeled “DNC” for “Do Not Connect”/”N/C” for “Not Connected” (connecting to these pins may short the Pi, so it is recommended to avoid these).

GPIO pins can be used as an input or an output. As an input, the pin can distinguish between two values: HIGH*  and LOW. As an output, you can send an ON, or HIGH signal (3.3 VDC), or an OFF, or LOW signal (0 VDC). These pins can be used for tons of physical tasks, like turning on/off lights (Christmas light choreography, anyone??), controlling motors, reading sensors, and honestly pretty much anything you can conceive, as long as you build a proper circuit.

Some of the GPIO pins also have more specific functions, such as SDA (data line), SCL (clock), etc.; if you’re reading this as a beginner don’t worry about these just yet. When you find a project you’re excited about you’ll naturally learn these functions as necessary.
*High input threshold is a signal of ~ 1.8 VDC, although it can vary between 0.8 – 2.0 VDC. This means that any signal coming in to your GPIO pin that is above 0.8 VDC may be read as “HIGH” by the RPi.

Advanced users will be happy to know that you can modify many of the GPIO characteristics from software (this link also has the robust GPIO electrical specifications).

For absolute beginners, here are some helpful things to know about the GPIO pins:
ac-dc-voltageGPIO pins operate on Direct Current (DC) voltage. Unless you want to see smoke come out of the RPi, do NOT input Alternating Current (AC) signals, like the one that comes out of the wall.
Be very careful about what you connect to the GPIO pins. You will not be able to control a motor directly from a GPIO pin; in this instance, the GPIO pin functions as a switch, rather than the actual power for the motor. Here’s a great tutorial on how to control a small motor.

Looking for more inspiration? Here’s a general list of 25 cool things to do w/ your RPi! You can also Google “Raspberry Pi projects” or browse the Instructables website for RPi projects.

The next post will cover a simple circuit you can build and control w/ the RPi.

Setting up a Raspberry Pi to Control Physical Objects, Pt. 1

RaspberryPiLogosmallThere are a slew of relatively simple systems to control physical objects w/ software. The most popular options are Arduino, the Raspberry Pi, and BeagleBoard. I’m an avid Raspberry Pi advocate, so let’s start with that!

The RPi is a simple & inexpensive computer that has general purpose input and output (GPIO) pins that interface w/ the real world.

(This tutorial assumes you are a beginner, but some technical jargon is included. Please feel free to comment if a term or phrase is not clear.)

What is a Raspberry Pi?RaspiModelB-1024x902

The Raspberry Pi is a credit-cared sized computer created by the Raspberry Pi Foundation, an educational charity based in the UK. It is designed to promote programming, computing, and interfacing with the physical world. It can control pretty much anything you are capable of conceiving.

There are two versions of the Pi:

  • Model A is cheaper w/ fewer features; 256 MB of RAM, one USB port and no Ethernet port.
  • Model B is more expensive, but has 512 MB of RAM, two USB ports, and a 100mb Ethernet port.

Where to purchase:

You can buy a Raspberry Pi from a variety of distributors. Model B from Adafruit is $40 (+ shipping & handling).

Other supplies:

RaspPiStarterKitThe Pi is literally just a computer. You’ll need a few additional supplies to set it up and use it (unless you’re a wizard). Think of it like a puzzle: collect the remaining pieces to customize an inexpensive interactive computer! To make the process easier, here’s a list of parts w/ explanations (you probably already have some):

  1. Power Cord
    The Pi runs on a micro-USB power supply, similar to many phone chargers. More specifically, the Pi needs 5 VDC and at least 700 mA. The Pi Foundation recommends a power supply that can provide 1200 mA. You can get one for less than $10, best values ~ $5, if you’re crafty you can find cheaper (or free). Here’s a google search for some that meet the best specs. Take note of where the power cord plugs into: wall socket, USB, etc.
  2. SD Card
    The Pi needs an SD card for physical memory storage (it doesn’t have a built-in hard drive or solid state drive). For ~ $6, you can buy an SD card with a pre-installed operating system and necessary software from the Pi Foundation’s Swag store here.
    With slightly more effort, you can buy any generic SD card and download the software here. This is fairly easy with a Mac system; if you chose to go down this route, here’s a great tutorial.
  3. Monitor & Display cable: HDMI/DVI cable or RCA composite video lead.
    Most modern monitors and TVs have HDMI ports for video (you can connect your RPi to your TV, woo!!). If you don’t already have one lying around, HDMI cables are found at RadioShack, Best Buy, Amazon, Ebay, etc. You can also get a HDMI converter cable for monitors or TVs w/ different ports. Older monitors are easy to find for free; many places of business, colleges/universities, and friends are happy to part with old monitors, or you can check out e-waste recycling bins.
  4. USB Keyboard & mouse (easiest way to set up).
    Any keyboard and mouse w/ a USB connection will work w/ the Pi.

Optional Supplies:

  1. Raspberry-Pi-Geek-Cases-1Ethernet Cable  (easiest way to connect to the Internet for Model B).

    Usually blue and lying around in some pile of cords you know are important. You can also buy them at places like Radio Shack, Best Buy, Amazon, etc.
  2. USB WiFi chip.
    Getting a USB WiFi “dongle” (yes, that is actually what it is called..) will allow you to connect to the Internet w/out an Ethernet cable. This requires some fairly involved setup, but it is completely doable for a RPi user of any experience level. Here are two methods:
    –Using wicd-curses,
    –Using GUI application
  3. Audio Lead (if not using HDMI)
    To get sound w/out an HDMI cable, you’ll need a standard 3.5mm jack to connect to speakers or headphones.
  4. Case
    The Raspberry Pi is designed to be a bare-bones computer to reduce cost as much as possible. However, cases are helpful protection from inevitable accidents and improve the mechanical connection of cables. There are TONS of awesome cases made specifically for the Raspberry Pi, although feel free to get creative and make your own!

Basic Setup:


  1. Insert SD card. Plug the RPi into a monitor & connect the keyboard and mouse via USB. An Ethernet cord is also recommended as it makes installing software on the RPi much easier.
  2. Plug the power cord into the RPi. Make sure you see a light turn on. (Yes, I honestly needed to include this step because this is an all too frequent problem for me.)
    Always do this after everything else is plugged in.
  3. If everything has been connected properly, you will see a start-up window. Every operating system (OS) will be different, but initial setup is simple and manageable.
    If you have a pre-loaded RPi-specific OS, or you have Raspbian or Adafruit’s OS, here’s a super straightforward tutorial on how to fully configure the RPi.Changing a few basic settings will definitely make life easier. From personal experience, if you have an SD card larger than 2 MB it’s useful to initially expand root partition to use the full SD capacity. If you want to avoid a command line window, you can specify Desktop launch whenever you power up the RPi.The default username is “pi” and the password is “raspberry”.Note: Since every OS is different, if your Pi doesn’t launch into the startup window, if you are still on the terminal window type “startx” into the command line. If that doesn’t work, leave a comment and we can troubleshoot together!
  4. Essentially that’s it! Once you’re at the desktop, you can use the Pi much like any other computer! Some basic programs: Midori is a simple Internet browser, Leafpad is a word processing program, Idle is a Python programming environment, and Scratch is kid-friendly programming language.

I will add more on how to set up the wireless, or other topics as requested.