1Series first: Connect battery (+) → Bulb A → Bulb B → battery (−) in one single loop using crocodile clips.先做串联：用鳄鱼夹把 电池(+) → 灯泡A → 灯泡B → 电池(−) 接成一个单一的回路。
2Observe brightness, then unscrew one bulb. What happens to the other?观察亮度，然后拧下一个灯泡。另一个灯泡会怎样？
3Parallel next: Connect both bulbs as two separate paths between the same two nodes. Each bulb gets its own direct route to the battery.再做并联：把两个灯泡接成两条独立的支路，连在同样的两个节点之间。每个灯泡都有自己直通电池的路径。
4Observe brightness, then unscrew one bulb. Does the other one stay on?观察亮度，然后拧下一个灯泡。另一个还会亮吗？
🔴 Series
🔴 串联
Dimmer · One breaks = both dark · Like old Christmas lights
更暗 · 一个坏掉 = 两个都灭 · 像老式圣诞彩灯
🟢 Parallel
🟢 并联
Full brightness · One breaks = other stays on · Like your home lights
满亮度 · 一个坏掉 = 另一个照常亮 · 像你家里的灯
🤔 Think About It
🤔 想一想
Why do old-style Christmas light strings go completely dark when just one bulb burns out?为什么老式的圣诞彩灯串，只要有一个灯泡烧坏，整串灯就全灭了？
2
Resistor Explorer
电阻探索家
★★ELEGOO KitELEGOO 套件
🎯 Use the breadboard for the first time and see how resistor size directly controls LED brightness.
🍞 Show realistic breadboard layout (Fritzing-style)🍞 显示真实面包板接线图（Fritzing 风格）
Power module 5V → red (+) rail → resistor → LED long leg (+); LED short leg (−) → green jumper → blue (−) GND rail. Swap the resistor value and watch the brightness change.
1Set your power supply module to 5V. Connect the + and − rails on your breadboard.把电源模块设到 5V。接好面包板上的 + 和 − 电源轨。
2Insert the LED: long leg (+) in one row, short leg (−) a row away.插入 LED：长脚(+)插在一行，短脚(−)插在隔开的另一行。
3Connect 5V → 100Ω resistor → LED (+) → LED (−) → GND. Notice the brightness.连接 5V → 100Ω 电阻 → LED(+) → LED(−) → 地(GND)。留意一下亮度。
4Swap in 220Ω, 1kΩ, 10kΩ one at a time. Record what you see in the table above.依次换上 220Ω、1kΩ、10kΩ。把你看到的记录到上面的表格里。
🔬 The Science: Ohm's Law
🔬 原理：欧姆定律
V = I × R — Voltage = Current × Resistance. Higher resistance means less current flows, so the LED gets dimmer. The resistor is a "gatekeeper" that controls how many electrons get through per second.V = I × R —— 电压 = 电流 × 电阻值。电阻值越大，流过的电流越小，LED 就越暗。电阻就像一个"守门员"，控制每秒钟有多少电子能通过。
🤔 Think About It
🤔 想一想
What happens if you remove the resistor completely? (Try it for just 2 seconds — feel the LED. Why do you think it gets warm so quickly?)如果把电阻完全去掉会怎样？（只试 2 秒钟——摸一摸 LED。你觉得它为什么这么快就发热了？）
3
Dimmer Knob Light
旋钮调光灯
★★★ELEGOO KitELEGOO 套件
🎯 Use a potentiometer (a twistable resistor) to smoothly control LED brightness — just like a real dimmer switch.
🍞 Show realistic breadboard layout (Fritzing-style)🍞 显示真实面包板接线图（Fritzing 风格）
Pot: right leg → 5V (red), left leg → GND (green). The middle "wiper" leg → 220Ω → LED (+); LED (−) → GND rail. Turning the knob changes the wiper voltage, so the LED dims and brightens.
A potentiometer has 3 legs. Looking at the flat front of the knob:
• Left pin → connect to GND
• Middle pin (wiper) → this is the output that goes to the 220Ω resistor
• Right pin → connect to 5V
Turning the knob moves an internal slider between the left and right pins.
1Set power supply to 5V. Insert the potentiometer into the breadboard (it has 3 pins, all in a row).把电源设到 5V。把电位器插到面包板上（它有 3 只脚，排成一排）。
2Wire: Left pin → GND, Right pin → 5V.接线：左脚 → 地(GND)，右脚 → 5V。
3Wire from Middle pin (wiper) → 220Ω resistor → LED (+) → LED (−) → GND.从中间脚（滑动端）接线 → 220Ω 电阻 → LED(+) → LED(−) → 地(GND)。
4Slowly turn the knob from one end to the other. The LED should smoothly brighten and dim!把旋钮从一端慢慢转到另一端。LED 应该会平滑地变亮变暗！
🔬 The Science: Variable Resistance
🔬 原理：可变电阻
A potentiometer is a resistor with a sliding contact inside. Turning the knob changes how much of the resistor's length is in the circuit — from nearly 0Ω all the way to 10,000Ω. More resistance = less current = dimmer LED.电位器是一个内部带有滑动触点的电阻。转动旋钮会改变接入电路的电阻长度——从接近 0Ω 一直到 10,000Ω。电阻值越大 = 电流越小 = LED 越暗。
🤔 Think About It
🤔 想一想
Why do we still need the 220Ω resistor even though the potentiometer is there? What would happen if the potentiometer was turned all the way to 0Ω with no safety resistor?既然已经有了电位器，为什么还需要那个 220Ω 电阻呢？如果把电位器一路转到 0Ω，又没有这个保护电阻，会发生什么？
⭐ Bonus
⭐ 进阶挑战
Put a small piece of tape on the potentiometer shaft and mark "brightest" and "just barely on" positions. How many degrees apart are they?在电位器的旋钮轴上贴一小块胶带，标出"最亮"和"刚好微亮"的位置。它们相差多少度？
4
Capacitor Fade-Out Switch
电容渐灭开关
★★★ELEGOO KitELEGOO 套件
🎯 Press a button to light the LED — then watch it slowly fade out on its own, like a hallway light that delays before switching off.
🪣A capacitor is like a tiny rechargeable bucket. When you press the button, it fills with charge in a split second. When you release the button, it slowly drains — and that draining current keeps the LED glowing!
🪣电容就像一个可以反复充电的小水桶。当你按下按钮时，它瞬间就充满了电。当你松开按钮时，它慢慢放电——而这股放电的电流会让 LED 继续亮着！
⚠️ IMPORTANT: Electrolytic capacitors have polarity!
The leg marked with a "−" stripe (or shorter leg) must go to GND. Putting it in backwards can damage the capacitor.
⚠️ 重要：电解电容有正负极之分！
标有"−"条纹的那只脚（或者较短的那只脚）必须接到地(GND)。接反了可能会损坏电容。
Circuit Diagram
电路原理图
🍞 Show realistic breadboard layout (Fritzing-style)🍞 显示真实面包板接线图（Fritzing 风格）
5V → button → Node A. From Node A two parallel branches: (1) capacitor + leg → GND (the bucket that drains slowly), and (2) 1kΩ → LED (+) → GND. Release the button and the draining capacitor keeps the LED glowing. Watch capacitor polarity: + leg to Node A, striped (−) leg to GND.
3Also connect Node A → capacitor (+) → capacitor (−) → GND (this branch is in parallel with the LED+resistor).再连接 节点A → 电容(+) → 电容(−) → 地(GND)（这条支路和 LED+电阻 是并联的）。
4Press the button: LED lights up instantly as capacitor charges.按下按钮：电容充电的瞬间，LED 立刻亮起来。
5Release: LED slowly fades over 1–3 seconds as capacitor drains. ✨松开：电容放电时，LED 会在 1–3 秒内慢慢渐灭。✨
🔬 The Science: RC Time Constant
🔬 原理：RC 时间常数
Fade time ≈ R × C. With a 1kΩ resistor and 470µF capacitor: 1,000 × 0.000470 = 0.47 seconds. Use a bigger capacitor → longer fade. This "RC time constant" is used in real camera flash circuits, car courtesy lights, and more!渐灭时间 ≈ R × C。用 1kΩ 电阻和 470µF 电容：1,000 × 0.000470 = 0.47 秒。换更大的电容 → 渐灭时间更长。这个"RC 时间常数"在真正的相机闪光灯电路、汽车车内灯等很多地方都用得到！
⭐ Bonus Challenge
⭐ 进阶挑战
If your kit has a larger capacitor (e.g. 1000µF), swap it in. Does the LED stay on longer? Time it with a stopwatch and record the difference!如果你的套件里有更大的电容（比如 1000µF），换上去试试。LED 亮的时间会更久吗？用秒表计时，把差别记下来！
5
Auto Night Light
自动夜灯
★★★★ELEGOO KitELEGOO 套件
🎯 Build a sensor circuit that automatically turns on an LED when it gets dark — no button needed, ever.
An electronic switch with 3 legs: Base, Collector, Emitter. When enough current enters the Base, the switch "opens" and current flows from Collector to Emitter.
🍞 Show realistic breadboard layout (Fritzing-style)🍞 显示真实面包板接线图（Fritzing 风格）
Left = light-sensor divider: 5V → 10kΩ → Node A → LDR → GND. Orange wire taps Node A into the transistor Base (B). Right = LED branch: 5V → 1kΩ → LED (+) → LED (−) → Collector (C); Emitter (E) → GND. In the dark the LDR's resistance rises, Node A voltage climbs, the transistor switches on, and the LED lights.
1Set power supply to 5V. Insert the PN2222 transistor into the breadboard (3 legs in separate rows).把电源设到 5V。把 PN2222 三极管插到面包板上（3 只脚分别插在不同的行）。
2Wire the left branch: 5V → 10kΩ resistor → Node A → LDR → GND.接好左边支路：5V → 10kΩ 电阻 → 节点A → LDR → 地(GND)。
3Connect a wire from Node A to the Base (B) pin of the transistor.从节点A 接一根线到三极管的基极(B)脚。
4Wire the LED branch: 5V → 1kΩ resistor → LED (+) → LED (−) → Collector (C) → Emitter (E) → GND.接好LED 支路：5V → 1kΩ 电阻 → LED(+) → LED(−) → 集电极(C) → 发射极(E) → 地(GND)。
5Power on, then cover the photoresistor with your hand. The LED should light up! Uncover it — it should go off.通电，然后用手盖住光敏电阻。LED 应该会亮起来！把手拿开——它应该会熄灭。
🔬 The Science: Voltage Divider + Transistor Switch
🔬 原理：分压电路 + 三极管开关
The 10kΩ resistor and LDR form a voltage divider. In the dark, the LDR's resistance is very high, so most of the 5V appears at Node A — enough to turn on the transistor's Base. The transistor then acts as a switch, connecting the LED circuit and lighting it up.10kΩ 电阻和 LDR 组成了一个分压电路。在黑暗中，LDR 的电阻值非常高，所以 5V 的大部分电压都落在节点A 上——足以让三极管的基极导通。三极管这时就像一个开关，接通 LED 电路，把灯点亮。
⭐ Bonus Challenges
⭐ 进阶挑战
• Replace the LED with the buzzer from your Sntieecr kit — make an alarm that beeps in the dark!
• Swap the photoresistor for the thermistor — build a heat-activated indicator instead.• 把 LED 换成 Sntieecr 套件里的蜂鸣器——做一个天黑就响的警报器！
• 把光敏电阻换成热敏电阻——做一个遇热触发的指示器。
⚠️ Safety Rules
⚠️ 安全须知
Breadboard voltage: Always use the 5V setting on the power supply module — never higher.
Something feels hot? Disconnect the battery immediately and check your wiring.
Capacitor polarity: Electrolytic capacitors must be inserted with correct + and − legs.
Don't short-circuit: Never connect + directly to − without a component in between.
LED eyes: Don't look directly at a bright LED at close range.
面包板电压：电源模块始终用 5V 档——绝不要调更高。
感觉有东西发烫？立刻断开电池，检查你的接线。
电容极性：电解电容必须按正确的 + 和 − 脚插入。
不要短路：绝不要在中间没有任何元件的情况下，把 + 直接连到 −。
当心眼睛：不要近距离直视很亮的 LED。
🏆 Progress Tracker
🏆 进度追踪表
Challenge
挑战
Difficulty
难度
Kit
套件
Date Done
完成日期
Series vs Parallel串联 vs 并联
★★
Sntieecr
Sntieecr
Resistor Explorer电阻探索家
★★
ELEGOO
ELEGOO
Dimmer Knob Light旋钮调光灯
★★★
ELEGOO
ELEGOO
Capacitor Fade-Out电容渐灭
★★★
ELEGOO
ELEGOO
Auto Night Light自动夜灯
★★★★
ELEGOO
ELEGOO
Fill in the date each time you complete a challenge. Go for it, Jeremy! 💪⚡