parts
Every part, explained from zero.
One page per component in the toolbox, in the order the ladder hands them to you. What it is, how it works with the numbers shown, the mistakes everyone makes, and a live circuit to poke at.
Level 1 · Light
- What a 3×AA battery pack does — 3×AA battery pack (4.5 V): The push that gets electrons moving. 4.5 volts — safe to touch.
- How a breadboard works inside — Solderless breadboard: Your building plate. Push parts in, pull them out, no glue, no solder.
- What jumper wires are for — Jumper wires: The roads electricity travels between parts.
- LED forward voltage explained — Red LED (5 mm): A tiny light with a one-way door — current only flows long-leg-in.
- Yellow LED resistor calculation — Yellow LED (5 mm): Like the red LED, in caution-light yellow.
- Why green LEDs need 2.1 volts — Green LED (5 mm): Like the red LED, in go-light green.
- What a 220 ohm resistor is for — 220 Ω resistor: A speed bump for electricity. This one protects LEDs.
- When to use a 1k ohm resistor — 1 kΩ resistor: A bigger speed bump — about five 220s stacked.
- What a 10k ohm resistor is used for — 10 kΩ resistor: A big speed bump, used for sensing tricks later.
- Slide switch (SPDT): which legs to wire — Slide switch: Opens or closes the loop. On means the loop is complete.
- How a tactile push button works — Push button (tactile): A switch that only stays on while you press it.
Level 2 · Sound
- Active buzzer vs passive: polarity and wiring — Active buzzer (3–5 V): Give it power, it beeps. It makes its own tone inside.
- How a potentiometer works — 10 kΩ potentiometer: A resistor with a knob — twist to change the speed bump size.
Level 3 · Sense
- How an LDR light sensor works — Light sensor (LDR): A resistor that changes with light: bright = small, dark = huge.
- How a thermistor works — Temperature sensor (10 kΩ thermistor): A resistor that changes with temperature.
- How a 2N2222 transistor switches — NPN transistor (2N2222): An electric switch flipped by electricity — a tiny current controls a big one.
- 2N3906 PNP transistor: pinout and how to wire it — PNP transistor (2N3906): The NPN’s upside-down twin: it switches the + side, and turns on when its base is pulled low.
Level 4 · Motion
- How a small DC motor works — DC motor (3 V): Turns electricity into spin.
- 1N4001 diode: stripe, 0.7 V drop and flyback use — Diode (1N4001): A one-way street for current. Protects circuits from motor kickback.
Level 5 · Control
- SG90 servo: wire colours, 50 Hz pulse and power — Micro servo (SG90): A motor that turns exactly as far as you tell it.
- What a 9 V battery is for — 9 V battery (PP3) + snap clip: Twice the push of the AA pack. Too much for an LED on its own — which is exactly why you learn to regulate it.
- What a 100 ohm resistor is used for — 100 Ω resistor: Half a 220. The LED resistor for a regulated 3.3 V rail, where there is less voltage to burn off.
- What a 100k ohm resistor is used for — 100 kΩ resistor: Ten 10 kΩs stacked. A pull-down for inputs that draw no current: MOSFET gates and logic pins.
- 3.3 V zener diode (1N4728A): resistor math — Zener diode 3.3 V (1N4728): A diode built to conduct backwards at exactly 3.3 V, so it pins a voltage no matter what the battery does.
- What a 2N7000 MOSFET does — MOSFET 2N7000: A transistor switched by voltage, not current. Its gate draws nothing, so any signal can drive it.
Level 6 · Logic
- What a 555 timer chip does — 555 timer chip: The most famous chip ever — it blinks, beeps, and keeps time.
- What a 10 µF capacitor does — 10 µF capacitor: A tiny rechargeable bucket for charge — fills and empties to keep time.
- What a 100 nF capacitor is for — 100 nF capacitor: A very small charge bucket that smooths out electrical wobbles.
- What a CD4011 NAND gate chip does — CD4011 quad NAND: Four NAND gates in one 14-pin chip. Every other logic function can be built from these.
- What a CD4017 decade counter does — CD4017 decade counter: Counts clock pulses from 0 to 9 and lights one of ten outputs for each count. The chip behind every LED chaser.
Level 7 · Code
- What an Arduino Nano is — Arduino-compatible board (Nano): A brain for your box. Now every part you own can be programmed.
Level 8 · Environment
- How the DHT11 sensor works — Temperature + humidity sensor (DHT11): Reads the room: how warm, how humid.
- How a soil moisture sensor works — Soil moisture sensor: Tells you when a plant is thirsty.
Level 9 · Robotics
- L293D motor driver: pinout and H-bridge wiring — Motor driver (L293D): Lets your small brain safely boss around big hungry motors.
- What TT gear motors do for a robot — Gear motors + wheels (pair): Slow, strong spin — the legs of every robot you will build.
Level 10 · Connected
- What an ESP32 board is — ESP32 Wi-Fi board: A brain with Wi-Fi. Your projects can now text you.
Nothing matches that yet.