- Material List
- Safety First
- Battery & Electronics Safety
- What is Electricity?
- What is a Circuit?
- Circuit Componets
- Part I: Let’s Build a Circuit: Basics
- Step 1: Make an Open Circuit
- Step 2: Close the Loop
- Step 3: Add a Switch
- Part II: Measure It (Multimeter, Switch & More Batteries)
- Step 1: Connect the Probes
- Step 2: Measure Voltage on One Battery
- Step 3: Add a Second Battery
- Part III: Series and Parallel
- Step 1: Series Circuit
- Step 2: Build a Parallel Circuit
- Part IV: Breadboards and LEDs
- Step 1: Test an LED with a Coin Battery
- Step 2: How Does a Breadboard Work?
- Step 3: Place the Empty Battery Holder
- Step 4: Make Room for More LEDs
Let’s build a circuit! We’ll start with an LED and a coin battery, then try lighting multiple LEDs on a breadboard. Along the way, we’ll go over voltage, current, and resistance, and see what happens when we connect lights in series and parallel.
Prerequisites: None! You don’t need any electronics experience to get started. Risks: Connecting a battery’s + and – sides directly creates a short circuit. This can make the battery heat up quickly, so check your connections before adding power.
Ai disclosure! Document info was pulled form documentation I made from a pervious workshop. To save time Claude and Notion Ai helped to transfer information from google doc into Notion Template below. Some text generation may be present.
Material List
Safety First
Battery & Electronics Safety
What is Electricity?
What’s moving in our wires? Tiny particles called electrons! Electrons have a negative charge. In a simple battery circuit, they move through the wires and parts from the negative (–) side of the battery toward the positive (+) side. This movement of charge is an electric current, which transfers energy to the parts in our circuit.
Three words help us describe electricity in a circuit:
Name | Description | Unit | Symbol |
Voltage (V) | The “push” that causes current to flow | volt | V |
Current (I) | The flow of electrons in a circuit | amp | A |
Resistance (R) | Opposes (slows down) current flow in a circuit | ohm | Ω |
Voltage, current, and resistance are related through a formula named Ohm’s Law: V = I × R. Think of voltage as the “push” and resistance as what restricts the flow. For a given voltage, increasing resistance reduces current. Choose a series current-limiting resistor for the LED and supply rather than assuming every coin cell safely limits current.
What Is Electricity and How Does It Work? | Constellation
What is a Circuit?
A circuit is a closed path in which an electric current can flow. Electrons travel from the negative (–) side of the battery, through the wires and parts, and back to the positive (+) side. But what happens if there’s a gap? The circuit is open, so no steady current flows. We need a complete loop!
- To get started, we need a power source, a path for current to follow, and a load—something that uses electrical energy. In our circuit, the LED is the load.
- Short circuit: So what happens if there is too little resistance in your circuit? Current can become too high, causing your battery to heat up and drain quickly. Imagine a dam suddenly breaking open: the water rushes out without anything to regulate it. To avoid this, never directly connect the POSITIVE AND NEGATIVE sides of your battery!
- Circuits are often described with symbols in a diagram. Let’s look at the parts below and the symbols used to show them. More commonly used symbols can be found here.
Circuit Componets
Battery
This is our power source! The battery provides the voltage, or “push,” that causes current to flow. In the battery symbol, the longer line marks the + side.
Wire
Connects the parts so current has a path to follow. On a breadboard we use jumper wires. About wire colors: In this workshop, use red for + and black for –. The wires themselves work the same way. Stick with consistent colors for good design practice… and save yourself some confusion!
- Alligator clips
- Jumper wires
- Other conductive material!
Light Bulb
A light bulb turns electrical energy into light. Today we’ll use an LED, which stands for Light Emitting Diode.
- Incandescent bulb: Electrical energy heats a filament until it glows. These bulbs work either way around.
- LED [Light Emitting Diode]: Converts electrical energy into light with much less heat. But there’s a catch—an LED only lights in one direction! We’ll test this in a minute.
Resistor
A resistor limits the current flowing through a circuit. Think of it as a narrow section of pipe that restricts the flow. Resistance is measured in ohms (Ω). For the same battery voltage, more resistance means less current.
In our LED circuits, a resistor helps keep too much current from flowing through the LED and damaging it. Put one resistor in series with each LED branch: battery + → resistor → LED → battery –. The facilitator will help you choose the right resistance for your LED and battery.
Unlike an LED, a resistor works either way around—its legs don’t have a + or – side!
Switch
A switch opens and closes the path in our circuit. Close the switch and current can flow. Open it and you’ve made a gap, so the light turns off. Closed = connected = ON. Open = gap = OFF.
Part I: Let’s Build a Circuit: Basics
The most basic circuit is a light and a battery. We’ll use one AA battery in a holder, two alligator clips, and an incandescent bulb in a holder to make a complete loop.
Supplies: One AA battery and holder, two alligator clip leads, and an incandescent bulb in a holder. Check the bulb’s voltage rating with the facilitator.
Step 1: Make an Open Circuit
- Get one AA battery holder with a battery in it. Find the + end of the battery. The red lead connects to + and the black lead connects to –.
- Get a bulb in a holder. Notice the two metal tabs with screws. These are where we connect our wires.
- Clip a black alligator clip from the holder’s black (–) lead to one tab on the bulb holder.
- Is the bulb on? Not yet! There’s a gap, so the circuit is open.
Step 2: Close the Loop
- Clip a red alligator clip from the holder’s red (+) lead to the other tab on the bulb holder. You’ve closed the loop, so your bulb should light up!
- Now swap the clips so red goes to the tab black was on. Does the bulb still light? Incandescent bulbs work either way around. (Remember this when we get to LEDs!)
- Disconnect one clip when you’re done. Bulbs get warm, and an open circuit saves the battery.
But… what if your bulb doesn’t light? Is the bulb screwed all the way into its holder? Are the alligator clips biting onto bare metal, not the plastic? Is the battery facing the right way in the holder? Still nothing? Try a fresh battery or bulb.
Step 3: Add a Switch
- Open the switch (handle up).
- Rebuild your Part I circuit with the switch in the loop: battery + → switch → bulb → battery –. Use one alligator clip for each connection.
- Close the switch. Your bulb should light! Open it again. The bulb turns off because you’ve made a gap.
- Closed = connected = ON.
- Open = gap = OFF.
You have now added your switch in series to the bulb! We will talk about this more soon
Part II: Measure It (Multimeter, Switch & More Batteries)
Multimeters are used to find out more information about your circuit. The main parts of a multimeter are the display, dial, ports, and probes. The dial is marked with what the meter can measure, like DC and AC voltage, resistance, current, and continuity. Image Source: https://arduinotogo.com/2016/08/22/chapter-2-the-multimeter/
Step 1: Connect the Probes
- Plug the black probe into COM and the red probe into VΩ. Leave the A and mA ports alone for today.
Set the Dial to DC Voltage
- Turn the dial to DC voltage (V⎓). Our batteries will give us less than 20V, so choose 20 in the V⎓ section.
- Never use a current (A) setting across the battery! That can create a short circuit.
Step 2: Measure Voltage on One Battery
- Touch the red probe to the battery’s + side and the black probe to –.
- What does the display say? A fresh AA battery reads about 1.5V.
- Try switching the probes. What changes on the display?
Bulb Specs
Step 3: Add a Second Battery
Our battery holders snap together end to end, so the + of one battery connects to the – of the next. When batteries are connected this way, their voltages add up.
- Open the switch. Predict: what will the meter read with 2 batteries? With 3?
- Snap a second battery holder onto the first. Measure across the whole battery pack: red probe on the + end, black probe on the – end.
Compare Bulb Brightness
- Connect your bulb to the battery pack. What happens to the brightness as you add batteries?
More voltage = more push = more current through the bulb = brighter light!
Part III: Series and Parallel
If we wanted to add more components or lights to our circuit parallel and series are two ways of completing a circuit. Image Source: https://www.electricalclassroom.com/series-and-parallel-circuits/
Step 1: Series Circuit
In a series circuit, current flows through the first bulb and then onwards to the next, and so on until it makes its way back to the battery. Parts connect one after another in a single loop. If one bulb breaks or is removed, the flow of current is broken. This will shut off all the bulbs in the circuit.
Lets add a second bulb to our circuit in series.
What do you notice? Use multimeter to confirm findings
Step 2: Build a Parallel Circuit
In a parallel circuit, current flows through separate branches and then back to the battery. Each bulb has its own connection to the battery. If one bulb breaks, current can still flow through the other branches and the other bulbs will stay on.
What Did You Notice?
Bulbs in a parallel circuit are brighter than bulbs in series. Why? In a series circuit, the bulbs share the battery’s voltage. Some of the voltage drops across each bulb, so each one gets less push. In a parallel circuit, each bulb has a direct connection to the battery, so each one gets the full battery voltage. The voltage across each part is called… yep, you guessed it, voltage drop! You can use a multimeter to measure voltage drop anywhere in your circuit. This is important in larger circuits, where you want to make sure you have enough voltage to run every part. Tip: Parallel bulbs are brighter, but they also use up the battery faster, because the battery is powering two full branches at once.
Part IV: Breadboards and LEDs
Breadboards and LEDs: Overview
An LED is a Light Emitting Diode. This type of diode converts electrical energy into light. Diodes only allow current to flow in one direction, so if you connect an LED backwards, it won’t light. A breadboard, despite its name, is not actually used for bread! Its purpose is to help us prototype circuits, so we can try out connections and make changes before committing to a design. In the past, circuits were built on wooden boards used for cutting bread. Now breadboards are plastic, but the name still remains.
Step 1: Test an LED with a Coin Battery
- Look at your LED. Notice that one leg is longer than the other. It matters which leg touches which side of the battery!
- The longer leg is positive (+), called the anode. The shorter leg is negative (–), called the cathode. You can usually find a flat edge on the LED rim on the negative side, too.
- Diodes only allow current to flow easily in one direction. Connect the LED backwards and it won’t light!
Keep Track of the Positive Leg
Tip: Give the long (+) leg a slight bend before building. This gives you a way to tell positive from negative once the legs are in the breadboard!
Step 2: How Does a Breadboard Work?
Breadboards are marked with letters and numbers to help you find the little holes, called pins. Letters label columns and numbers label rows.
Find the Connected Strips
- Inside are metal strips that connect some of the pins. In the middle, the five pins A–E at one row number connect to each other. F–J make a separate group. Notice the gap? The connections don’t go across it!
- The long + (red) and – (blue) rails along the edges usually connect lengthwise. These are used for power. Some boards have a break partway down.
- Check your board with the multimeter’s continuity (beeper) setting before adding power. Touch the probes to two pins in the same strip, then to two separate strips. A beep means they’re connected. Never test continuity with a battery connected.
Step 3: Place the Empty Battery Holder
- Place your empty battery holder on the breadboard. Make sure the + and – pins go into separate strips that are not connected. It is important that these do not connect! Choose holes that fit your holder, and don’t force the pins.
Wire and Light One LED
- Now add an LED. Put it across the center gap. For example, put the long (+) leg in E15 and the short (–) leg in F15. These holes are on separate strips, even though they share a row number.
- Take a red jumper wire and a resistor. We want this path: holder + → resistor → LED +. Connect the red jumper from the holder’s + strip to a spare strip. Put one resistor leg in that spare strip and the other in the strip with the LED’s long leg. Make sure the resistor’s legs are on different, unconnected strips, or current can bypass it!
- Take a black jumper wire. Connect the strip with the LED’s short (–) leg to the holder’s – strip.
Step 4: Make Room for More LEDs
The outermost rails of the breadboard are used to connect to the + and – sides of a power source. This keeps our wiring organized and gives us room for more parts.
Connect the Power Rails
- Take the battery out first!
- Connect the holder’s + strip to the + rail with a red wire.
- Connect the holder’s – strip to the – rail with a black wire.
- Reconnect your LED branch so the path is + rail → resistor → LED +, then LED – → – rail. Check your work, then put the battery back in. Your LED should still light!
Add Three More LED Branches
- Remove the battery again. Add three more LED branches, each with its own resistor and connections to the + and – rails. Check your work, then put the battery back in.
- Is this series or parallel? Predict what will happen if you remove one LED. Take the battery out, remove an LED, then reconnect power to test your idea.
But… What If Your LED Doesn’t Light?
First, take the battery out. Are the LED’s + and – legs the right way around? Does the battery face the right way in its holder? Check the LED, resistor, and jumper wire connections. Are they in holes that actually connect? Check for breaks in the power rails, too. Once the wiring is checked, put the battery back in and test again. Still no light? Measure the battery voltage with your multimeter or try a fresh battery.
