Beginning Circuits Challenge Card Ideas¶
Ideas for challenge cards built around breadboard electronics without a microcontroller — LEDs, resistors, buttons, potentiometers, and a multimeter — per Chapter 16's electrical safety rules, Ohm's law, and first-circuit fundamentals.
Beginning¶
Light Up an LED¶
Build the first breadboard circuit: a battery pack, a correctly sized resistor, and an LED wired so it lights, paying attention to the LED's long leg (positive) and short leg (negative). Stretch goal: swap in a different-value resistor and observe how the brightness changes.
Resistor Color Code Detective¶
Given five mystery resistors, use the resistor color-code chart to calculate each one's resistance value, then verify every calculation with a multimeter set to measure resistance. Stretch goal: find two resistors with different color bands that measure the same resistance.
Push-Button Powered LED¶
Wire a push button in series with an LED, resistor, and battery pack so the LED only lights while the button is physically held down, introducing digital input as a purely mechanical, no-code concept. Stretch goal: wire a second button so either button independently lights the LED.
Potentiometer Dimmer¶
Wire a potentiometer into an LED circuit so turning its knob manually varies the current reaching the LED, then use a multimeter to record the voltage at three different knob positions. Introduces the voltage-divider idea behind every analog input used later in the book. Stretch goal: mark the knob position that makes the LED just barely visible.
Two-LED Series vs. Parallel¶
Build the same two LEDs first wired in series, then rewired in parallel, comparing brightness by eye and measuring the voltage across each LED with a multimeter in both configurations. Stretch goal: explain in writing, using Ohm's law, why the brightness differs between the two wiring styles.
Intermediate¶
Ohm's Law Detective¶
Given a target current for an LED, calculate the resistor value needed using Ohm's law, build the circuit, then verify the actual current draw with a multimeter and compare it to the calculated target. Stretch goal: repeat the calculation and build for a second, different battery voltage.
Buzzer Alarm Circuit¶
Wire a push button, a buzzer, and a battery pack so the buzzer sounds only while the button is pressed. Stretch goal: add an LED on a second parallel branch so it lights at the same moment the buzzer sounds.
Static Electricity Safety Demo¶
Following the chapter's static-electricity precaution checklist, correctly discharge static electricity before handling a sensitive component, then write a short explanation of which specific step protects the component and why skipping it is risky. Stretch goal: identify which season or weather condition makes static discharge most likely in the club's own meeting space.
Short Circuit Spot-the-Difference¶
Given two nearly identical breadboard photos — one wired correctly and one with an accidental short circuit — identify exactly where the short is and explain the safety risk it creates. Stretch goal: safely reproduce a low-voltage version of the short circuit and measure how quickly the battery pack heats up.
Multimeter Continuity Scavenger Hunt¶
Use a multimeter's continuity setting to trace which rows and columns on an unfamiliar breadboard are electrically connected to each other, mapping the board's tie-point layout before ever applying power. Stretch goal: draw a simple diagram of the traced connections from memory, then check it against the actual breadboard.
Advanced¶
Two-LED Priority Logic Circuit¶
Build a circuit with two push buttons and two LEDs wired so that only one LED can ever be lit at a time, even if both buttons are pressed at once — solving the priority conflict with wiring alone, no microcontroller involved. Stretch goal: add a third "both pressed" state that lights neither LED.
Soldered Permanent LED Nightlight¶
Following the chapter's soldering safety workflow, solder — rather than breadboard — a simple LED, resistor, and battery holder into a permanent nightlight, then heat-shrink or tape every exposed lead. Often attempted with a partner given the added soldering-iron safety supervision required. Stretch goal: add a switch so the nightlight can be turned off without disconnecting the battery.
Voltage Divider Sensor Circuit¶
Build a photoresistor voltage-divider circuit and use a multimeter to record the voltage at several light levels — room light, a hand covering the sensor, a flashlight held close — then plot the readings to show a working analog light sensor without any microcontroller yet. Stretch goal: find the light level where the voltage crosses exactly half the battery's voltage.
Multi-Component Logic Board¶
Combine a potentiometer, two LEDs, and a buzzer on one board so the potentiometer's position determines which LED lights, and the buzzer only sounds once the potentiometer passes a set threshold. Often attempted with a partner given the wire count involved. Stretch goal: label the exact knob position where the buzzer first turns on.
Multimeter Mystery Box¶
Given a sealed breadboard circuit built by a mentor or another student, use only a multimeter — no visual inspection of the wiring — to diagnose and diagram what components are inside and how they're connected, following the same troubleshooting mindset later used on full robots. Stretch goal: identify a single deliberately broken connection inside the mystery box.