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!

Make Custom (& Inexpensive) Circuit Blocks!

Create, build, and play with your very own LEGO-inspired circuit blocks! Explore the basics of electricity and circuits, discover how sensors work and use ’em to design your own experiments, and incorporate upcycled materials to improve on your materials-sourcing & MacGuyver-ing skills! That old gum wrapper? Make it into a resistor or a switch!

But seriously, this is a super fun (and inexpensive) project/toy/game to teach electronics to kids (and adults!) of all ages and experience levels. The total cost of this project is under $30 and it takes about 2 hours to design and build.


Ok.. so where do we start?

First we need a base, the circuit block itself. This design uses breadboards* as the circuit block bases. I chose mini color breadboards so that each color denotes a specific type of electronic component (see next section). These are super cheap, typically less than $1 per board. Follow my design or create your own!

For each breadboard/component, we also need at least two or more breadboard wires (or 22 or 24 stranded wire), so for 20 breadboards with a single component we need 40 or more breadboard wires.

*Breadboards are non-edible, inexpensive prototyping boards for electronics projects. See photo above for a quick illustration of how breadboards work, or check out this tutorial.


Gather Electronic Components!

If you happen to have an assortment of electronic components around, gather them up and go through them to find the most choice pieces — we want components with only two leads, like simple motors, fans, LEDs, resistors, capacitors, etc. Check out websites like SparkFun or Amazon and search for electronic components.

Hey, wait, where can I get this stuff for free??

Dig up that box of broken electronics in your garage and see what you can find inside the electronics!

The best sources for components are electronic toys that move and/or make noise, speakers, telephones, and other medium-sized electronics.You’ll need wire cutters and pliers to remove the pieces, be sure to keep the legs intact so they can easily connect to the breadboard.

Avoid smartphones, tablets and laptops since the circuit components are suuuuper small and difficult to attach to a breadboard (unless that’s what you’re going for, then extract away!). For safety reasons, avoid appliances (e.g. microwaves, televisions, refrigerators, etc.), and do not use capacitors that are larger than a child’s thumb.


Build the Circuit Blocks!

The breadboard assortment I got included red, blue, white, green and black, mini breadboards. I broke up the colors into the following categories and components:


Red boards (power devices): One 1 W solar panel, one 9V battery clip, one 2 AA battery box, and two coin cell cases.




Blue boards (simple active): one motor w/ propeller, six LEDs of different colors (three per board), and one transistor (the transistor is pretty tricky — I’d recommend replacing this with another motor).




Green boards (sensors): one photoresistor, one buzzer/piezoelectric sensor, one peltier junction, and one capacitive sensor (this didn’t end up working, so replace it with a pressure sensor or other cool, two-lead sensor).




White boards (simple passive): six resistors of varying values (three per board), two (small electrolytic) capacitors of different values, and one potentiometer.





Black boards (electromechanical): Two pushbutton switches of different sizes/types (one per board), two toggle switches (single board), and one cooling fan.




To build each circuit block:
Connect each component to the first rows of each breadboard (be sure they aren’t shorted — should be on either side of the breadboard), and hot glue the wires into place. Remember to label which side is positive and which side is negative! Another fun option is to make labels for each component.


Plug & Play!

You’re ready to start building circuits and teaching other people the basics of electronics! Start simple, then add in more components to explore their function and see how they affect your circuit.

Here’s an example progression exploring different ways to light up an LED:

1. Use a coin cell to light up an LED.

Exploration questions: Does orientation matter? Where do the wires need to connect to the breadboard?

2. Use the solar panel to light up an LED. Move the panel into the shade (or cover it with your hand), and see how the LED brightness changes.

Exploration questions: How does the brightness of the LED change when you cover the solar panel? Why does this happen?

3. Use a coin cell and potentiometer to adjust the brightness of an LED.

Exploration questions: What do you notice? Does it matter how we connect the potentiometer?

4. Use a coin cell and a photoresistor to adjust the brightness of an LED.

Exploration questions: What do you notice?. Does it matter how we connect the photoresistor? How could we use the photoresistor in an experiment?

Build your own sequences to teach folks about specific circuit components or sensors, or use them as a fun & educational free-time project!

Make a Light-Up Holiday Card!

Light-up cards incorporate two of the best worlds of making (electronics and crafts) with the added bonus of making somebody smile. Heck yes!

Here’s my approach to light-up cards and my favorite recent discoveries: pop-ups and cotton balls.

Read time: ~ 5 min.

Build time: ~ 30 min -1 hr (mostly crafting the card)

Cost: < $5



Gather up the following materials:

  • One or more LEDs!
  • Copper tape (~ 20″)
  • One coin cell
  • One paper clip
  • One pushpin
  • Colored paper
  • & any other craft materials your creative heart desires!


Build the Circuit!



1. Cut out a pocket for the coin cell.




2. Add copper tape to cardstock!

Stick 2″ of copper tape just above the battery pocket, so that the bottom of the battery rests on top of it. This is the negative (-) side of the circuit.

Stick another 2″ piece of copper tape on the underside of the pocket, so that it touches the top of the battery. This is the positive (+) side of the circuit.


3. Add a switch!

Cut a small line at the end of the copper tape, push paper fastener through the slit and hook the paperclip under the paper fastener (it might also help to add copper tape to the end of the paperclip). This makes an “on/off” switch!



4. Connect the LED!

The longer LED leg connects to the positive side of the circuit. The shorter leg connects to the negative side of the circuit. Be sure that these two sides of the circuit do not cross, or it “shorts” the LED and drains the battery.



Design & Make the Card!

1. Plan out where the light is going to go!

This is super crucial if you want the light to be in a specific spot, like the top of a tree, as a nose, etc. It’s helpful to make a super simple drawing of what you want before you try, or at least have extra materials on-hand for second (or possibly third) versions. Check all the things before you glue stuff down.

2. Craft the card!

Since it’s the December holiday season, I’m making a bunch of holidays cards for friends, woo! I like incorporating re-used (or upcycled) materials, so for this card I cut out the cover of an old calendar and folded the edges under to make it 3D (oooohhh now we’re gettin’ fancy!).

Another fun option are pop-ups! Cut out thin strips (~ 1/2 inch) and fold them accordion-style, then use ’em to prop up your cutouts and drawings!

3. Add in the LED!

You can either hide the circuit under the cover, or inside the card. For this card, the circuit slips under the cut-out, and the LED, covered by a lot of cotton balls, sticks out the top to light up the clouds!



Final Touches & Beyond!

Close the switch to the LED and stand in awe at your awesome creation! Write a heart-felt note on the inside and give it to your favorite family member/friend/coworker/neighbor/etc!!

There are tons of other ways to make the LED circuit! The photo to the left shows a method using magnets (ohhhh magnets!). What other ways can you come up with to make the circuit? Post your creations in the comments below!! 😀

Make a Sneaky Wearable ‘State Change Switch’!


Secretly change settings for your wearable outfits or use this button as a secret prank trigger! Here’s a quick & easy tutorial on how to build and program a “state change switch.” AKA a button that cycles through different settings. It’s super easy and has tons of practical applications!

Read Time: ~ 5 min
Build Time: ~ 30 min
Cost: Super cheap (>$5)



— Glove (just one.. but you should probably wear two to avoid giving away the secret)

— Three (3) stranded wire segments (24/26 gauge), approx. 3 ft

Wires should be long enough to reach from your palm to wherever you want to hide the electronics. I hid mine in a belt pouch, but you could also opt for a pocket, backpack, etc.

— One (1) 10kOhm resistor

— One (1) pushbutton (aka momentary switch)

— One (1) 1″ x 1″ piece of thin wood

Those free wood swatches at hardware stores are perfect!

— Microcontroller

I used the SparkFun EL Sequencer b/c I was using this switch to select different settings for my Hallowen EL Wire costume. Check out the tutorial to learn how to build your own version of this costume, or you can use this state change switch with any ol’ microcontroller for your own awesome project!


Build it!



1. Drill holes in a small piece of wood for the button feet.


2. Solder a wire to one of the button legs, and a resistor to the other button leg on the same side. Solder a black wire to the resistor.

3. On the other side of the button, solder a wire to the leg across from the resistor.

4. Test electrical connections, then coat all solder joints in hot glue.


5. Connect the black wire to the microcontroller ground, and the wire on the same side to the microcontroller voltage output (Vcc).

6. Connect the wire on the other side to a microcontroller digital (or analog) input pin (see schematic above), and then onward to programming!



Program it!


Most folks that program state change switches use the modular, or mod, operator* to tell different settings apart. It’s not perfect, but for how little code is involved it’s a good way to cycle through different settings and get back to our original state.

Here’s a quick sketch that will allow you switch between three different settings by pushing the button. As is, it’s written to switch between three different digital output settings. In other words, if you have a motor connected to your microcontroller, the button will switch the motor from constantly on, to pulsing (i.e. repeatedly on/off), to constantly off, then back to constantly on.

*The mod operator (usually “%”) divides the number by the value after the operator and gives you the remainder. For example, if you see: 10%2, it means 10 / 2 = 5, which equals 0, since there is no remainder. Another example is 10%3, which equals 1, since 10 / 3 = 3.33, and 0.33 is one out of three. Here’s more info on this or feel free to leave a comment if you have any questions!


Finish & Test!

Connect the button wire leads to your microcontroller inputs, run the full program and test to see that it works as expected. If it’s all good, put the glove on and push the state change switch and watch as your costume/insertotherawesomeprojecthere changes through different settings!

Now go forth and show off your project around town!

Sound Reactive EL Wire Costume

Bring science fiction to life with a personalized light-up outfit! EL wire is a delightfully futuristic-looking luminescent wire that has the added benefit of staying cool, making it ideal for wearable projects. Combining sensors and a microcontroller with EL wire allow for a wide range of feedback and control options.

This project uses the SparkFun sound detector and the EL Sequencer to flash the EL wire to the rhythm of ambient sound, including music, clapping, and talking.




El Wire comes in a variety of colors, so pick your favorite(s)!


  • Article(s) of clothing

For a Tron-esque look, go for stretchy black material. Yoga pants and other athletic gear work great!

  • Belt
  • Old jacket with large pocket, preferably zippered or otherwise sealable.

The pocket will house the electronics. If you intend to wear the costume outdoors in potentially wet weather, choose a pocket that is waterproof (i.e. cut a pocket from a waterproof jacket).

  • Piece of packing foam or styrofoam (to insulate the sound detector).


Build it! Pt. 1

CAUTION: Although it is low current, EL wire runs on high voltage AC (100 VAC). There are exposed connections on the EL Sequencer board so BE CAREFUL when handling the board. Always double (and triple) check that the power switch is OFF before touching any part of the board. For final projects, it is recommended to coat all exposed connections in epoxy, hot glue, electrical tape, or other insulating material.

1. Test EL Sequencer with EL Wire.
Connect the inverter, battery, and at least one strand of EL wire to the EL Sequencer. (Note that the two black wires of the inverter correspond to the AC side.)
Be sure that the EL Wire lights up and blinks when you power the EL Sequencer on battery mode.

2. Solder header pins onto 5V FTDI pinholes on the EL Sequencer and onto the VCC, ground, and A2 input pins.

3. Solder header pins to the sound detector.

4. Connect sound detector to EL Sequencer via female-to-female breadboard wires (or solder wire onto header pins).
Connect the sound detector VCC and ground pins to the VCC and ground pins on the EL Sequencer. Connect the sound detector gate output to the A2 input pin on the EL Sequencer. If you are using the envelope and/or audio output signals, connect these to pins A3 and A4 on the EL Sequencer (more on this in the Program It! section).

Build it! Pt. 2

1. Make a protective casing for the sound detector using packing foam or styrofoam to prevent jostling or other physical vibrations (aka collisions) from triggering it.

Place sound detector on top of foam, outline the board with a pen, and cut out a hole in the foam for the detector to fit snugly inside. Also recommended to epoxy the wires onto the foam (but not the sound detector board).

2. Cut out a pocket from the jacket and sew onto the belt.

3. Put belt on, connect EL Wire to EL Sequencer, and place EL Sequencer in pocket pouch. Determine approximate placement of each EL wire strand based on location of electronics.

Build it! Pt. 3

1. Mark and/or adhere the base of the EL wire JST connector onto clothing, allowing the full length of the connector to flex. Be sure that the JST connector can easily reach the EL Sequencer.

2. Starting at the basse of the JST connector, attach EL wire strands to your chosen article of clothing.

Sew EL wire onto clothing using strong thread or dental floss, or use an appropriate fabric adhesive.
Prior to adhering the EL wire, it is recommended to use safety pins to determine placement of the EL wire on each article of clothing while you are wearing it. EL wire is flexible but not so stretchy, so give yourself some wiggle room.

It is also recommended to use separate EL wire strands on different articles of clothing to facilitate the process of taking it on/off.

Program it!  

1. Connect EL Sequencer to computer via 5V FTDI BOB or cable. 

2. Program the EL Sequencer using the Arduino platform; the EL Sequencer runs an ATmega 328p at 8 MHz and 3.3V.

3. Determine how you want to use the sound detector output(s) to control the EL wire. The sample program below utilizes the gate channel output to turn on the EL wire if there is a sound detected.

Sample Program:

// Sound Activated EL Wire Costume<br>// Blink EL Wire to music and other ambient sound.
void setup() {
  // The EL channels are on pins 2 through 9
  // Initialize the pins as outputs
  pinMode(2, OUTPUT);  // channel A  
  pinMode(3, OUTPUT);  // channel B   
  pinMode(4, OUTPUT);  // channel C
  pinMode(5, OUTPUT);  // channel D    
  pinMode(6, OUTPUT);  // channel E
  pinMode(7, OUTPUT);  // channel F
  pinMode(8, OUTPUT);  // channel G
  pinMode(9, OUTPUT);  // channel H
//Initialize input pins on EL Sequencer
  pinMode(A2, INPUT);
void loop() 
  int amp = digitalRead(A2);
  //If Gate output detects sound, turn EL Wire on
  if(amp == HIGH){
    digitalWrite(2, HIGH); //turn EL channel on
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
    digitalWrite(2, LOW); //turn EL channel off
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);

This program is just one example of what is possible with the SparkFun sound detector. Depending on your needs, different responses can be achieved by using the “envelope” and “audio” outputs of the sound detector. The EL Sequencer can individually control up to 8 different EL wire strands using the three sound detector output signals, so there are tons of possiblities to customize your sound-activated outfit!

More information about the sound detector output signals:
The gate channel output is a digital signal that is high when a sound is detected and low when it is quiet. The envelope channel output traces the amplitude of the sound, and the audio output is the voltage directly from the microphone.

In the photo provided, the red trace corresponds to the gate signal output, the light green trace corresponds to the envelope signal output, and the dark green trace corresponds to the audio signal output.

Test, Secure, & Show Off!

Connect all components to the EL Sequencer (inverter, battery, sound detector) and place in belt pouch. Turn the system on, make some noise (e.g. clapping, snapping, or music) and check that the EL wire flashes when there is a sound.

If the outfit works as expected, secure all connections by coating them in a (thin) layer of epoxy. Let dry for at least 24 hours. Epoxy is a very permanent adhesive, so if you want to reuse any of the components, try other adhesives like hot glue or electrical tape (less secure, but adjustable and removable).

You can reduce the overall strain on individual connections by ensuring that wires are securely fastened to the belt and/or pouch approximately one inch (1″) from all connections. The goal is to allow the EL wire to flex while keeping electrical connections rigid, as the connections are the most likely point of breakage.

Wear your one-of-a-kind, high-tech outfit and go show it off to the world!

Simple LED Earrings


Wearables are an awesome, relatively new extension of circuits. Conductive threads & fabrics make it easy to attach components like LEDs and sensors to clothing/accessories. Plus, they are a super fun introduction to electronics!

These LED earrings were designed b/c I wanted a wearable that was simple, unique, and could be built by-hand w/ available materials. Purchasing all materials adds up to less than $10, and these can be built in ~ 1 hour (although it does take some patience).

For this tutorial I’m assuming you are an electronics beginner. Regardless of your background, I hope this project inspires you to design your own wearable technology or take the basic concepts to the next level 🙂


Step 1: Materials


— 2 LEDs
Fun fact: LEDs on the higher end of the rainbow (red, orange, & yellow) use less power than colors on the lower end (purple, blue, & green).

— 2 Lithium coin cell batteries, 3 V
Mine are non-rechargeable and will probably last for ~20 hours. If you want to make them to last longer, use rechargeable batteries (super expensive but worth it if you want to wear the earrings long-term).

— Thread— Conductive Thread
Used to attach the LED to the battery. Alternatively, you can use wire or anything else that conducts.. like magnets!Also, since conductive thread loops tend to come undone, I hot glued all the knots to hold them together.

— 2 earring backs
— 2 clasps
These act as a switch so the LED can be turned off when not in use. I had some necklace clasps on hand which worked perfectly, but there are tons of options for switches.. all you need is a way to interrupt the flow of electricity.
I used conductive tape, but honestly regular tape works just as well.

Step 2: Tools


— Hot glue gun
— Scissors
— Needle
Recommended to get a needle w/ a wide eye b/c the conductive thread has a tendency to fray.
— Optional: wire cutters
Helps w/ cutting the ends of the LEDs.

Step 3: Build it! Pt 1: Wrap the battery.

Screen shot 2014-11-26 at 2.11.34 PM

Wrap the battery w/ 1.5 – 2 feet of (normal) thread. To make it easier, tape the beginning end of the thread to the back of the battery. Leave at least 6 inches of thread at the end.

When finished wrapping, loop the end of the thread under the band and pull tight. Repeat this a few times, then make a knot. Tape the end/thread band down.

Step 4: Build it! Pt. 2: Attach earring back.



Loop the 6 in. tail of the the thread band through the hole in the earring back. Use the needle to loop the thread under the band & pull tight, kind of like sewing a button. Repeat at least ten times, or until the thread runs out, then tie a knot.

Step 5: Build it! Pt. 3: Attach the Positive LED Leg.


Tie 6 inches of conductive thread to the positive (longer) leg of the LED. Loop the conductive thread through the bottom of the battery thread band and pull through, leaving the LED ~ 1/2 inche (in.) below the battery. Pull the conductive thread down, so it is only touching the front cover (positive side) of the battery.

Loop the conductive thread around the battery thread band at least five times, then tie a knot. Hot glue the conductive thread knots w/ the littlest amount of glue to help hold it in place.

Step 6: Build it! Pt. 4: Attach Clasp.

Screen shot 2014-11-26 at 2.17.42 PM

Attach the clasp (aka switch) to the back of the battery w/ ~ 6 in. conductive threadin the same way the earring back was attached: thread the end of the earring back through the thread band on the battery, above the tape, and pull it tight. Repeat at least five times. Tie a knot and hot glue the thread to hold it in place.

Step 7: Build it! Pt. 5: Attach Negative LED Leg.

Screen shot 2014-11-26 at 2.20.26 PM

Tie the other end of the clasp/switch to 6 in. conductive thread. Tie the end of the conductive thread to the negative, shorter leg of the LED, leaving ~ 1/2 in. from the bottom of the battery. Hot glue the knots.

Connecting the two ends of the clasps helps w/ finding the right length.. or you could use a ruler 🙂

Be sure that the LED legs and the respective thread/wires do not touch; otherwise the battery is shorted and the LED won’t turn on.

Step 8: Done! Woo!


That’s it! Clean up the mess that is hot glue, snip the ends of the conductive thread and, if you’re not going to put them on right away or take photos, unscrew the clasps.

And have fun dazzling your friends and all that good stuff 🙂
Note: The reason the green one isn’t as bright is probably because the battery was quite bit older.