part · Level 1 · Light · connect
How a breadboard works inside
Solderless breadboard — Your building plate. Push parts in, pull them out, no glue, no solder.
What it is
A breadboard is a plastic plate full of holes with metal clips hidden underneath. Push a part's leg into a hole and the clip grabs it and makes an electrical connection. Pull it out and the connection is gone. No solder, no glue, endlessly reusable.
The trick is knowing which holes are already wired together. In the main area, each short row of five holes is one connected strip. Down the long edges run the power rails: a whole column of holes joined together, marked with a red + line and a blue − line.
A groove runs down the middle. It splits every row in two, so the five holes on the left are not connected to the five on the right. Chips sit across that groove so their two rows of legs land on separate strips.
How it works
Think of each five-hole strip as one point in your circuit — one wire junction. Two legs in the same strip are touching electrically; two legs in different strips are not, until you add a jumper.
Use that as the rule. To put a resistor in series with an LED, the resistor's second leg and the LED's long leg share a strip. To connect two things in parallel, both their + legs share one strip and both their − legs share another.
The clips add almost no resistance — a few milliohms — so a breadboard does not change the math of any circuit at 4.5 V. What it can do is add mystery: on many boards the power rail is broken in the middle, so the top half and bottom half of the same rail are two separate strips. If a project works on one half of the board and dies on the other, bridge the gap with a jumper.
Holes are spaced 2.54 mm (0.1 inch) apart, the standard for hobby parts and chips, so everything in your box fits.
The numbers
| Holes per strip | 5 — a, b, c, d, e joined; f–j joined; the groove splits them |
|---|---|
| Hole spacing | 2.54 mm — 0.1 inch — matches every DIP chip and header |
| Power rails | 2 per side — red + and blue −; often split halfway down |
| Clip resistance | < 0.01 Ω — ignore it in calculations |
| Wire that fits | 22 AWG solid — thinner falls out, thicker bends the clips |
See it working
The First Light circuit, simulated live. Open it on the Workbench to change anything.
simulating…
Mistakes everyone makes
- Both legs of a part in the same strip. The part is shorted out and does nothing. Fix: legs go in different rows, always.
- Assuming the whole power rail is one piece. Half the rail is dead. Fix: look for a gap in the printed red/blue line; add a jumper across it.
- Straddling the groove with a two-legged part and expecting rows to join. They do not. Fix: a jumper across the groove if you need that connection.
- Bent legs pushed in at an angle. They touch a neighbour's clip or miss entirely. Fix: straighten legs with pliers; push straight down until you feel the click.
- A chip inserted in one half only. Its two rows of pins are shorted together. Fix: chips always sit across the groove.
Questions people ask
- Which holes on a breadboard are connected?
- Each row of five holes on one side of the middle groove is one strip. The long rails on the edges are connected top to bottom (sometimes with a break in the middle). Rows are not connected to each other, and the two sides of the groove are not connected.
- Do I need to solder a breadboard?
- No. The spring clips under each hole hold parts firmly enough for any battery-powered project. Solder is for when a design is finished and you want it permanent.
- Why does my circuit work on one side of the breadboard and not the other?
- Most likely the power rail is split halfway along. Bridge the gap on both the + and − rails with two short jumpers.
Projects that use this part
- 🔦 First Light — Build a real flashlight circuit and learn why every circuit is a loop. L1 · 15 min
- 📡 Morse Code Messenger — A push button, an LED, and a secret code — send real messages with light. L1 · 20 min
- 🎈 Twin Reds — Two red LEDs on one loop — same current, half the leftover push, and a lesson in how voltages stack when parts sit end to end. L1 · 15 min
- 🚦 Tabletop Traffic Light — Three LEDs on three parallel lanes, all lit by one switch — build a tabletop traffic light and discover parallel circuits. L1 · 25 min
- 🔐 The Vault — Two buttons, one loop — the LED only lights when BOTH are pressed at the same time. L1 · 15 min
- 🚪 Do Not Disturb Sign — A green "chill" LED plus a switched red "leave me alone" LED — two lanes on one battery, and a switch that only touches one of them. L1 · 20 min
- 🤝 Handhold Chain — Three switches in a line — the LED only lights when all three are closed at once. AND, one step past The Vault. L1 · 15 min
- 🚪 Two-Door Signal — Two slide switches in parallel, one shared LED — either switch alone lights the lamp. The OR gate, at Level 1. L1 · 15 min
- 🚨 Signal Light — A slide switch and a push button in parallel — the slide is the steady beacon, the button is the extra flash. Either lights the lamp. L1 · 15 min
- 🛟 Escape Hatch — The Vault with a big red emergency button wired around both locks — turn BOTH keys, or hit the button, and the light comes on. L1 · 20 min
- 🧪 The Brightness Lab — Run a real experiment: predict, measure with your eyes, and prove Ohm's law. L1 · 30 min
- 🔔 Door Buzzer — Your first sound circuit — a real doorbell for your bedroom door. L2 · 20 min
- 🎛️ Dial-a-Brightness — Twist a knob and watch the LED fade up and down — your first "how much" input. L2 · 20 min
- 📻 Dial-a-Buzz — Dial-a-Brightness for sound — one knob rides the buzzer between full alarm and library silence, with no button in the way. L2 · 15 min
- 🔧 Continuity Tester — Your first real tool — two probe wires that beep and light up whenever the tips touch anything that conducts. L2 · 20 min
- 🚨 Panic Doorbell — Two buttons wired so either one fires the same buzzer and light — your first OR gate. L2 · 20 min
- 🔈 Whisper Alarm — A doorbell with a volume knob — the pot lives in the buzzer lane, so twisting it changes the beep without touching the light. L2 · 25 min
- 🛎️ Two-Tone Doorbell — Two call buttons, one doorbell: LOUD rings the buzzer and lights the porch LED; QUIET starves the buzzer and shows why it can't just be dimmed. L2 · 25 min
- 🚨 Arm & Ring — A doorbell that ignores you unless a hidden slide switch is armed first — series-AND with sound, plus an 'armed' LED that shows the state. L2 · 20 min
- 🔔 Twin Bells — One doorbell button rings two buzzers in parallel — one in your room, one in the kitchen — with a slide switch that mutes just the bedroom bell at night. L2 · 20 min
- 🖐️ Two-Hand Bell — Two push buttons in series feeding a buzzer and an LED — both hands must stay pressed for the alarm to sound. L2 · 20 min
- 🔕 Silent Alarm — Three panic buttons wired in parallel, all inside an armed lane — any one of them fires the buzzer, and a small LED tells you the alarm is watching. L2 · 25 min
- 🎮 Quiz Buzzer — Two teams, two big buttons: yours lights your LED and rings your buzzer, theirs does the same on their side. Two independent doorbells sharing one battery. L2 · 20 min
- 🌙 Automatic Night Light — A light that switches itself on when the room gets dark — no hands, no code. L3 · 35 min
- 🌅 Sunrise Alarm — The night light — flipped. Swap two parts and the LED wakes up with the sun instead. L3 · 25 min
- 🍪 Cookie Jar Alarm — The Sunrise Alarm's brain wired to a buzzer instead of a lamp — quiet in the dark jar, screaming when the lid comes off. L3 · 25 min
- 🪤 Trip Wire Alarm — A thin wire across a doorway holds the alarm silent. Break the wire and the buzzer screams — until you connect it back. L3 · 25 min
- 🌡️ Warm Hand Alarm — Cup your hand over the sensor and the LED lights up — a thermometer that turns into a switch. L3 · 30 min
- 📖 Reading Light — The Automatic Night Light with a knob on top — turn it to dial in how dark the room has to get before the lamp fires. Your first tunable threshold. L3 · 30 min
- 🏝️ Vacation Nightlight — The Automatic Night Light with a manual override — flip the slide switch off and the lamp stays dark even in a pitch-black room. L3 · 25 min
- 📚 Study Lamp — The Automatic Night Light with a force-on override — flip the slide switch and the lamp stays lit even in daylight, ignoring the sensor. L3 · 25 min
- 🌆 Curfew Beeper — The Automatic Night Light's brain with a buzzer where the LED used to sit — beeps the moment the room goes dark, so you never miss sunset. L3 · 30 min
- 🤒 Fever Beeper — The Warm Hand Alarm's brain wired to a buzzer instead of a lamp — silent in a normal room, beeping the second a warm palm covers the sensor. L3 · 25 min
- 🌇 Dusk Chorus — The Curfew Beeper with a red LED wired in parallel with the buzzer — one dusk sensor drives a chime and a lamp at the same time. L3 · 30 min
- 🎺 Warm Hand Chorus — Fever Beeper with a red LED added in parallel with the buzzer — one warm-hand sensor drives a chime and a lamp at the same time. L3 · 30 min
- 🌀 First Spin — Your first motor. A switch, a coil, and a diode that catches the voltage kick when the current stops. L4 · 15 min
- 💨 Handheld Fan — Press the button, the fan spins. A tiny finger current commands a hundred-milliamp motor through a transistor. L4 · 20 min
- 🌞 Sunrise Fan — Sunrise Alarm with the LED swapped for a motor. The sun rises, the fan starts — an automatic wake-you-up desk breeze. L4 · 25 min
- 🆘 Panic Fan — Two buttons, either one fires the fan. Panic Doorbell wearing a motor — an OR gate that spins. L4 · 20 min
- 🎉 Party Spinner — One button, three mouths: a spinning motor, a red LED, and a buzzer all fire together. One transistor drives them all. L4 · 25 min
- 🚗 Twin Wheels — Two motors from one button — a Level 9 robot drivetrain, five levels early. L4 · 25 min
- 🎚️ Dial-a-Spin — Dial-a-Brightness with a motor instead of an LED. Twist the knob and watch the fan speed slide from full spin to a slow crawl. L4 · 20 min
- 🕸️ Trip Wire Fan — Trip Wire Alarm's brain wearing a motor. The wire is intact — the fan is silent. Snap it — the fan spins as the alarm. L4 · 25 min
verified against: SparkFun — How to Use a Breadboard · Adafruit — Breadboards for Beginners