Featured Projects
8-bit CPU Simulator
Build and simulate a simple educational CPU from scratch, inspired by retro computing.
RF Signal Sniffer
A portable device for capturing and decoding RF signals from remotes and toys.
Educational Power Board
An isolated board that helps safely power and test analog/digital circuits.
All Projects by Level
Basic
| Project | Description | Core concepts | Sessions (est.) |
|---|---|---|---|
| Homework Focus Timer (25‑Minute 555 Monostable with End‑Beep) | A single‑button timer that turns on a “Focus” LED for exactly 25 minutes and then sounds a buzzer for ~5 seconds to signal a break. | 555 timer, monostable, RC timing, buzzer | 1 |
| Pedestrian Traffic Light Sequencer (555 + 4017) | A desk-sized traffic light that cycles Green (6 s), Yellow (1 s), Red (3 s) repeatedly, using a 555 timer and a CD4017 decade counter. Teens can relate it to crosswalk signals and learn deterministic sequencing and digital logic without coding. | 555 timer, RC timing, decade counter, digital logic, timers/counters, TDR | 1 |
| Automatic Night Light with Hysteresis (LDR + LM393 Comparator) | Build a small desk/bedside light that turns on automatically when the room gets dark and turns off when it’s bright again. Hysteresis prevents rapid flicker at the threshold, making behavior stable and predictable. Teens can use it as a night light or hallway marker. | comparator, hysteresis | 1 |
| Fridge Door Open Beeper with 30-Second Delay (CD4060 + Reed Switch) | A battery-powered reminder that beeps only if the fridge door stays open for about 30–35 seconds. Closing the door immediately silences the beeper. Teens can use it to avoid wasting energy and melting ice cream. | magnetic sensor, buzzer | 1 |
| Turn-Taking Counter (0–9) with Step Button (555 + 4017) | A simple “Now Serving” / turn-taking counter that lights one of 10 LEDs (0–9) each time you press the NEXT button. Great for board games, club activities, or organizing speaking turns. It’s deterministic and bounce-free thanks to a 555 monostable that generates a clean clock pulse for the CD4017 decade counter. A RESET button returns the display to 0. | 555 timer, monostable, RC timing, decade counter, digital logic, timers/counters | 1 |
| Mailbox “Mail Arrived” Latching Indicator (Reed Switch + CD4013) | A battery-powered, no-solder indicator that lights an LED and keeps it on after the mailbox door is opened, so you know mail has arrived. You reset it with a button. Uses a magnetic reed switch and a D flip-flop (CD4013) for a deterministic, reproducible latch. | D flip‑flop, latch, magnetic sensor | 1 |
| Three‑Button Combination Lock Simulator | A simple “locker code” device: press A, then B, then C to “unlock.” Each correct step lights an LED; the final green LED means unlocked. A Reset button clears the lock. Teens can relate this to unlocking a locker, a game chest, or a shared box. Behavior is deterministic and repeatable. | accelerometer, motion sensing, state machine | 1 |
| Bike Turn Signal and Brake-Priority Flasher (555 + Transistor Drivers) | A reliable bike signaling circuit: flip a switch to blink left or right turn signals at a steady rate; press a brake button to override and light both sides solid. Teens can relate to safer cycling and visibility. Behavior is deterministic: fixed blink rate, unambiguous brake priority. | 555 timer, RC timing, TDR, fast edges, power switching | 1 |
| Under-Sink Leak Alarm with Latching Light and Buzzer (CD4093 + CD4013) | A moisture-triggered alarm that sounds a buzzer and lights an LED when a leak is detected and keeps them on until you press Reset. Teens can place the sensor near sinks, washing machines, or aquariums to catch leaks early and protect school supplies or electronics. | D flip‑flop, latch, Schmitt trigger, buzzer, TDR, fast edges | 1 |
| Two‑Team Scorekeeper (0–99 each) with Pushbuttons (CD4510 + CD4511) | A tabletop scoreboard for games, debates, or chores that lets two players/teams increment their scores from 00 to 99 with one button per team and a master reset. It uses up‑counters and 7‑segment drivers, so behavior is deterministic and reproducible. | BCD counter, digital logic, 7‑segment driver, 7‑segment display, timers/counters, power switching | 1–2 |
| Fastest-Finger Quiz Buzzer Lockout (4 Players) | A four-player “first to buzz” system for quiz games. The first button pressed lights that player’s LED and sounds a buzzer. All other buttons are locked out until Reset is pressed. | buzzer, state machine | 1 |
| Automatic Laptop Cooler Fan (Temperature-Triggered) | A 5 V fan turns on automatically when your laptop (or game console) warms up and turns off when it cools down. An LM393 comparator monitors a thermistor stuck near a hot spot and drives a transistor for the fan. Teens can use it to keep devices cooler during gaming or homework without remembering to flip a switch. | comparator, temperature sensing, TDR, fast edges, sensors | 1 |
| Two-Door Chime: Dual-Tone Doorbell | A two-button doorbell that plays two distinct tones (front and back doors) using two 555 astable oscillators and a single speaker. Teens can install it for a bedroom or study, instantly knowing which button was pressed by the tone. Behavior is fully deterministic and repeatable. | 555 timer, astable, RC timing | 1 |
| Pocket Metronome: Tempo‑Adjustable Beep-and-Blink (555 Astable) | A battery-powered metronome that produces steady ticks and LED flashes for music practice. The tempo is set with a knob and stays deterministic from about 48 to 190 beats per minute. Kids and teens can use it to keep time while practicing instruments, clapping rhythms, or timing drills. | 555 timer, astable, RC timing, buzzer, TDR, fast edges | 1 |
| Closet/Locker Auto Light with 2‑Minute Off‑Delay (555 Monostable) | Opens the door, light turns on. Close the door, light stays on for about 2 minutes then shuts off automatically to save batteries. Retriggers any time the door is opened again, so the light stays on while you’re using the closet/locker. Useful for closets, lockers, cabinets, or toy chests. | 555 timer, monostable, RC timing, TDR, fast edges | 1 |
| Backpack/Bike Tether Break Alarm (Latching Siren) | A simple anti-theft alarm teens can use to secure a backpack or bike by threading a loop wire through a strap or wheel. If the loop is pulled out or cut, the buzzer and LED latch on and stay on until manually reset. Behavior is deterministic and reproducible. | buzzer, TDR, fast edges | 1 |
| Plant Watering Interval Reminder (3-Day Latching Blink + Beeper) | Build a reminder that, three days after you press “Reset after watering,” starts a repeating blink + beep and keeps alerting until you reset it again. Kids and teens can use it to remember to water a plant regularly. | timer, latch, buzzer | 1–2 |
| Household Battery Health Bargraph Tester (LM3914, AA/AAA and 9V) | A deterministic LED bargraph tester that shows the remaining health of common batteries kids and teens use: 1.5 V AA/AAA cells and 9 V rectangular batteries. Flip the range switch for AA/AAA or 9 V, insert the battery under test, and read 1–10 LEDs (more LEDs = healthier battery). Includes a realistic test load so results are reproducible. | LED bargraph, display/UI | 1 |
| 24‑Second Basketball Shot Clock (CD4510 Down Counters + 555 Clock) | A sturdy, deterministic 24‑second countdown timer for gym or driveway practice. Press Reset to load “24,” flip Run to start counting down visually on two 7‑segment displays; when it reaches 00 it stops and sounds a buzzer until Reset is pressed. | 555 timer, RC timing, BCD counter, digital logic, 7‑segment display, buzzer | 2 |
| Hand Sanitizer Use Counter (IR Break-Beam, 0–99 Display) | Counts each sanitizer pump by detecting a hand breaking an infrared beam. Displays total uses from 00 to 99 on two 7‑segment displays, with a lockout to prevent multiple counts per single pump. Useful in classrooms, clubs, or family spaces to track sanitizer use. Deterministic one-count-per-break behavior. | IR sensor, 7‑segment display, timers/counters, state machine, TDR, fast edges | 2 |
Intermediate
| Project | Description | Core concepts | Sessions (est.) |
|---|---|---|---|
| Fridge Door Left-Open Alarm | A microcontroller monitors a magnetic reed switch on a fridge door. If the door stays open for more than 20 seconds, it warns with a pulsing buzzer and red LED. If it reaches 2 minutes, it sounds a continuous alarm until the door is closed. A green LED indicates closed, blue indicates open-but-within-limit, red indicates overdue. Powered by any USB source. | magnetic sensor, buzzer, TDR, fast edges, sensors | 1 |
| Hydration Reminder Bottle Coaster | A desk coaster that reminds you to drink water. When your bottle is on the coaster, a timer runs; if you don’t pick it up within 30 minutes, the coaster glows and beeps until you take a sip. Picking up the bottle resets the timer. Useful during study sessions to build healthy hydration habits. | timer, buzzer | 2 |
| Laundry Machine Vibration Notifier | A microcontroller-based device that detects when a washing machine finishes by sensing vibration and alerts you with a buzzer and flashing LED. Useful for dorms or shared homes to avoid forgetting finished laundry. | buzzer, TDR, fast edges, sensors | 2 |
| Desk Posture Coach (Ultrasonic Distance Trainer) | A desk gadget that measures how close you are to your screen with an ultrasonic sensor and coaches you to sit back. It shows green/yellow/red status with an RGB LED and beeps if you lean too close for more than a few seconds. Press a button once while sitting correctly to set your personal “good distance.” Useful for reducing neck strain during homework, gaming, or studying. | ultrasonic sensing, time‑of‑flight, RGB LED, buzzer, TDR, fast edges | 1–2 |
| Get-Up Alarm Floor Pad | A pressure-activated alarm that only turns off when you stand on a floor pad for a few seconds—great for teens who snooze alarms and need to physically get up. | pressure sensor | 1 |
| CO2 Ventilation Reminder for Bedroom/Study | A compact desk device that monitors CO2 levels to remind you when to open a window for fresher air during study or gaming sessions. It shows live ppm on a small display, uses an RGB LED for green/yellow/red status, and sounds a short buzzer alert when CO2 gets high. A button snoozes the alert for 10 minutes. | RGB LED, buzzer, display/UI, sensors | 2 |
| Noise-Level Traffic Light for Study Sessions | A desk light that shows room noise at a glance. It reads microphone levels and lights green for quiet, yellow for moderately loud, and red when it’s too noisy to focus. Teens can use it to keep group chats or music in check during homework or streaming. | TDR, fast edges | 1 |
| Knock-Pattern Room Door Notifier | A door-mounted knock sensor that learns your unique knock rhythm and alerts you with lights and a tone when someone matches it. Teens can use it in dorms or bedrooms to get notified without loud doorbells and to filter random knocks. Completion time: 2 hours | sensors | 2 |
| Door-Triggered Garbage Day Reminder | A microcontroller-based reminder that alerts you to take out the trash when you first open the door on your scheduled day. It uses a reed switch to detect the door opening and an RTC clock to check the weekday and time window before buzzing and flashing an LED. A button silences the alert. Program the trash day and time window in code. | magnetic sensor, RTC, TDR, fast edges, sensors | 1–2 |
| Backpack Bike Brake + Turn Signal Light (Accelerometer + LED Strip) | A backpack-mounted light that shows bright red brake lights when you slow down and left/right arrow turn signals when you press buttons. Great for biking to school at dawn/dusk. The microcontroller reads an accelerometer to detect braking and controls an addressable LED strip to display patterns. | accelerometer, motion sensing, TDR, fast edges, display/UI, sensors | 2 |
| Plant Buddy: Soil Moisture Reminder with RGB Alert and Snooze | A desk-friendly plant helper that reads soil moisture and shows status with an RGB LED (green/amber/red). When the soil is too dry, it beeps until you press a button to snooze the alert for a set period. Teens can keep a plant alive without guesswork. | RGB LED, buzzer | 1 |
| Jump Rope Reps Counter + Interval Coach | Counts jump-rope passes using an infrared break-beam and shows the total on a 4-digit display. Beeps every 50 jumps and gives a triple-beep at 500. Press the button to reset the count between sets. Teens can use it to track workouts without looking at their phone. | IR sensor, buzzer, timers/counters, TDR, fast edges, display/UI | 1 |
| Umbrella Reminder Door Beacon (WiFi Weather Aware) | A WiFi-connected reminder beacon that checks the day’s local forecast every morning and alerts you (LED + buzzer + tiny screen) near the door if rain is likely. Teens can place it by the backpack hook to avoid forgetting an umbrella. Completion time estimate: 2.5 hours | buzzer, Wi‑Fi | 2-3 |
| FocusFlip Pomodoro Cube Timer | A flip-to-set study/break timer teens can use on a desk. Place the device in one of four orientations to select 25-min focus, 50-min focus, 5-min break, or 15-min break. An RGB LED ring shows progress; a buzzer chimes when time is up. One button starts/pauses. Uses an accelerometer/gyro to detect which face is “up.” | accelerometer, motion sensing, RGB LED, buzzer, display/UI, sensors | 2 |
| Smart Locker Check-In Reminder (RFID Tap-to-Verify) | A locker or backpack helper that makes sure you don’t forget essentials (textbook, calculator, ID card). Tap each tagged item on the reader when placing it in or taking it out. When you close the door (magnet sensor), the system checks if all required items are “checked in.” If anything is missing, it beeps and shows what’s missing on a small screen. | magnetic sensor, buzzer, sensors | 2 |
| BusBuddy: Live Bus Arrival Window Beacon | A WiFi-connected display and light/buzzer beacon that counts down to the next bus arrival at your stop. When the bus is near (e.g., under 8 minutes), the LED shifts from green to yellow to red and the buzzer beeps so you leave on time. Teens can use it to avoid missing the school or city bus without checking their phone. | buzzer, Wi‑Fi, display/UI | 2 |
| BrushBuddy: 2-Minute Toothbrushing Coach Cup | A toothbrush-holder “coach” that guides a full dentist-recommended 2-minute brush with visible progress and gentle pressure alerts. Detects brushing vibrations, shows a countdown on an LED ring, and gives a finish chime. Useful for teens who want a quick, reliable routine without phone apps. | timers/counters, display/UI, sensors | 2 |
| ShowerTime Coach: Steam-Based Shower Timer | A humidity-driven shower timer that detects steam with a DHT22 sensor and guides you with an LED ring and buzzer: green while you start, yellow as you approach your time budget, red when it’s time to wrap up, and a distinct buzzer pattern if you go over. Press the button before stepping in; it auto-adapts to your bathroom by reading the baseline humidity and starting when it detects a rise. Practical for teens sharing bathrooms or managing morning routines. | buzzer, display/UI, sensors | 1 |
| Sunrise Alarm Light Strip (WiFi Time‑Synced) | A gentle sunrise simulator that brightens an LED strip before your wake-up time to help you get out of bed naturally. It uses an ESP32 to keep accurate time over WiFi, an OLED to set/view the alarm, and a few buttons to set hours/minutes and toggle the alarm. | I2C, accelerometer, motion sensing, OLED display, buzzer, Wi‑Fi | 2 |
| UV‑Safe Badge: Sun Exposure Tracker + Reapply Reminder | Wearable breadboard badge that tracks your UV exposure at the beach, park, or game practice and nudges you to reapply sunscreen. A microcontroller integrates UV intensity over time, shows status with an RGB LED (green/yellow/red), and beeps when you hit your reapply threshold. A pushbutton resets the dose when you reapply. | RGB LED, buzzer, TDR, fast edges | 1 |
Advanced
| Project | Description | Core concepts | Sessions (est.) |
|---|---|---|---|
| Breadboard Audio Network Analyzer (20 Hz–20 kHz) with DDS Source and Precision Rectifier | A complete, breadboarded audio-frequency network analyzer that sweeps a clean sine from 20 Hz to 20 kHz and measures output magnitude of a device-under-test (DUT). An AD9833 DDS provides the stimulus; an analog front-end AC-couples, biases, and precision-rectifies the DUT output; an Arduino Nano controls the sweep and reads the rectified level with its ADC to stream results over USB for plotting. This lets you characterize filters, EQ circuits, transformers, guitar pedals, and audio stages. The build combines analog signal conditioning (rail-splitter, buffering, precision rectifier) and digital control (SPI DDS and ADC sampling). | DDS, SPI, ADC, accelerometer, motion sensing, timers/counters | 4–6 |
| 4‑Wire Milliohm Meter (10 µΩ–10 Ω) with Constant‑Current Source and I2C ADC Display | Build a precision 4‑wire ohmmeter for measuring very low resistances using a 10 mA constant‑current source, Kelvin sensing, a 16‑bit differential ADC (ADS1115), and an Arduino Nano driving a 16×2 I2C LCD. The design uses a shunt reference and an op‑amp controlled NPN current sink. Practical for characterizing PCB traces, contact resistance, shunts, motor windings, and cable joints. | ADC, I2C, motor control, TDR, fast edges, display/UI | 4–6 |
| Breadboard GPS‑Disciplined 10 MHz Oscillator (GPSDO) with Digital Divide‑by‑10^7 and Analog PLL | Build a GPS‑locked 10 MHz reference using a 5 V OCXO, a chain of CMOS decade counters to divide 10 MHz down to 1 Hz, a CD4046B phase comparator II, and an active PI loop filter driving the OCXO control voltage. The GPS 1PPS is the time standard; the loop forces the OCXO to align its long‑term phase to GPS, yielding a low‑jitter, accurate 10 MHz lab reference. This project combines digital logic (counters, phase detector) and analog control (PI loop with an op‑amp) on breadboards. | comparator, PLL, timebase, timers/counters, TDR, fast edges | 4–6 |
| Breadboard Lock‑In Amplifier (10 Hz–10 kHz) with MCU‑Generated Reference and Dual‑Phase Synchronous Detection | A single‑supply lock‑in amplifier that extracts microvolt‑level signals buried in noise by synchronous detection. An Arduino Nano generates a precise square‑wave reference (and its 90° quadrature), drives an excitation output for modulated sensors, and reads the in‑phase (X) and quadrature (Y) DC outputs after low‑pass filtering to compute magnitude and phase. Analog front‑end includes an instrumentation preamplifier, dual synchronous detectors using a CD4053 triple SPDT analog switch, and RRIO op‑amp buffering referenced to a precision mid‑rail. Results are displayed on a 0.96" I2C OLED. Practical for optical chopper experiments, resistive bridge sensors, magnetic pickup coils, and precision impedance measurements in the audio range. | I2C, magnetic sensor, OLED display, transimpedance amp, photodiode, TDR | 4–5 |
| Breadboard Discrete 10‑Bit SAR ADC (0–4.096 V) with R‑2R DAC, Sample‑and‑Hold, and LCD Readout | Build a working successive-approximation ADC from analog building blocks and an MCU: a CD4066 sample‑and‑hold front end, a 10‑bit R‑2R ladder DAC buffered by a rail‑to‑rail op‑amp, an LM393 comparator, a 4.096 V precision reference, and an Arduino Nano running the SAR algorithm. The LCD displays measured input voltage. Range: 0–4.096 V single‑ended. | comparator, DAC, ADC, display/UI, sensors | 3–4 |
| Breadboard Turbidity Photometer with Transimpedance Amplifier, Constant‑Current LED Driver, and 16‑bit I2C Readout | A precision single-wavelength (white LED) photometer for turbidity/absorbance measurements. The analog front end uses a low-noise transimpedance amplifier (TIA) for a BPW34 photodiode, and a closed-loop constant‑current LED driver set by MCU PWM. A 16‑bit ADC digitizes the TIA output, and a 16x2 I2C LCD shows readings. Built entirely on breadboards without soldering. | ADC, I2C, PWM control, transimpedance amp, photodiode, TDR | 3 |
| Breadboard Programmable Battery Cycler and Coulomb Counter (Single-Cell Li‑ion 2.5–4.2 V, 0–500 mA) | A microcontroller-controlled battery cycler that alternates charge and constant-current discharge for a single 18650 Li-ion cell. It measures voltage and bidirectional current, computes capacity (mAh/Wh), and displays live data. Analog loop sets discharge current via op-amp and MOSFET; digital I2C peripherals provide DAC setpoint, precision current/voltage readout, and LCD UI. Relays switch between charge and discharge paths. Built entirely on breadboards. | DAC, I2C, op‑amp, analog conditioning, timers/counters, TDR | 6–7 |
| Breadboard 1‑Bit Sigma‑Delta ADC Voltmeter (0–4.096 V, 10 SPS, ~18‑bit ENOB) with Analog Modulator and MCU Decimation | Build a first‑order sigma‑delta modulator in analog hardware (integrator + comparator + 1‑bit DAC) and decimate the bitstream in an Arduino Nano to display precision DC voltage readings on an I2C 16×2 LCD. Single‑supply design with a 2.5 V precision reference establishes the modulator common‑mode. The project emphasizes both analog stability and digital signal processing. Completion time estimate: 6–8 hours | comparator, DAC, ADC, I2C, TDR, fast edges | 6-8 |
| Breadboard Reciprocal Frequency Counter (0.1 Hz–50 MHz) with Analog Front‑End, 1 MHz Timebase, and 16×2 LCD | A precision reciprocal frequency counter that measures frequency from 0.1 Hz up to 50 MHz using external hardware counting for the input channel and a crystal oscillator-derived 0.1 s gate. An analog front-end conditions and protects the input, while a chain of HC counters generates an accurate gate window from a 1 MHz oscillator. An Arduino Nano reads a 24-bit hardware counter, computes frequency, and displays the result on a 16×2 LCD. Useful for RF/clock work, PLL validation, and general lab measurement. | I2C, PLL, timebase, timers/counters, display/UI, sensors | 3–4 |
| Breadboard 3‑Electrode Potentiostat (±1.0 V vs RE, ±2 mA) with I2C DAC/ADC and Single‑Supply Virtual Ground | A laboratory‑style three‑electrode potentiostat for electrochemical experiments. It controls the working electrode (WE) potential relative to a reference electrode (RE) by driving a counter electrode (CE), while measuring WE current with a transimpedance amplifier. The system uses a rail‑to‑rail dual op‑amp, an I2C DAC to set the target potential, and a 16‑bit I2C ADC for current and voltage readback, all powered from the Arduino’s 5 V and stabilized by a precision virtual ground. Suitable for cyclic voltammetry ramps (generated by the MCU), chronoamperometry, sensor/electrode characterization, and teaching electrochemistry electronics. | DAC, ADC, I2C, timers/counters, transimpedance amp, photodiode | 2 |
| Breadboard Ultrasonic Pulse‑Echo Distance Meter (40 kHz) with Analog Front‑End, T/R Switching, Envelope Detection, and MCU Timing | Build a pulse‑echo ultrasonic distance meter using discrete analog and digital electronics. A 40 kHz transmit burst is driven differentially to a piezo transmitter via a Schmitt‑trigger buffer. A receive transducer is protected during transmit by an analog switch, then amplified by a tuned multiple‑feedback band‑pass filter, further amplified, precision‑rectified, and smoothed to an envelope that the MCU reads on an ADC channel. The MCU gates the transmit burst, times time‑of‑flight, and displays distance on a 16×2 I2C LCD. The analog chain is biased at mid‑supply for single‑supply operation. No soldering; all on breadboards. | Schmitt trigger, ADC, I2C, ultrasonic sensing, time‑of‑flight, TDR | 4–6 |
| Breadboard Two‑Terminal I–V Curve Tracer (0–10 V, 0–20 mA) with DAC Drive, 16‑bit ADC, and 128×64 OLED | A precision two‑terminal I–V curve tracer for diodes, LEDs, Zeners, resistors, and sensors. A 12‑bit DAC generates a linear sweep that an op‑amp amplifies to 0–10 V. A fixed series resistor limits current to <20 mA. A low‑side shunt measures current with a 16‑bit ADC while another ADC channel measures DUT voltage through a divider. A 128×64 I2C OLED plots the curve in real time. Controlled by an Arduino Nano. All on breadboards with no soldering. | DAC, ADC, I2C, OLED display, TDR, fast edges | 2–3 |
| Breadboard Single‑Phase Power and Energy Meter (True RMS, Real Power, Power Factor) with Isolated CT and AC Sense | Build an isolated AC power/energy meter that measures RMS voltage, RMS current, real power (W), apparent power (VA), power factor, line frequency, and cumulative watt‑hours for 50/60 Hz mains. It uses an AC wall‑wart for voltage sensing isolation, a clip‑on current transformer for load current, anti‑alias filters and a buffered mid‑scale reference, and an MCU that synchronously samples voltage and current, computes per‑cycle metrics, and displays results on a 16×2 I2C LCD. All electronics are low‑voltage and fully breadboarded; the only mains interaction is via the isolated sensors. | I2C, timers/counters, TDR, fast edges, synchronous sampling, display/UI | 3–4 |
| Breadboard K‑Type Thermocouple Thermometer (−200 to +1200 °C) with Instrumentation Amplifier, Cold‑Junction Compensation, and 16‑bit I2C ADC | Build a precision thermometer that reads a K‑type thermocouple using an instrumentation amplifier with level shift, a precision 2.048 V reference, a 16‑bit ADC, and a cold‑junction digital temperature sensor. An Arduino Nano performs linearization and displays the result on a 16×2 I2C LCD. The analog front‑end allows measuring microvolt-level signals with good noise immunity on a single 5 V supply. | ADC, I2C, temperature sensing, TDR, fast edges, display/UI | 3–4 |
| Breadboard Two‑Channel Phase and Gain Meter (0.5 Hz–1 kHz) with Schmitt Comparators, Period Timing, and 128×64 OLED | Measures phase difference (−180° to +180°) and amplitude ratio between two low‑voltage periodic signals (sine/triangle/square, 0.5 Hz–1 kHz, 0–5 Vpk) using analog conditioning and dual zero‑crossing Schmitt comparators, with digital timing on a microcontroller and live readout on an OLED. Practical for characterizing filter phase shift, amplifier gain, and synchronizing actuators/sensors. | Schmitt trigger, comparator, I2C, OLED display, TDR, fast edges | 2–3 |
| Breadboard Avalanche-Noise True Random Number Generator (TRNG) with Comparator, Von Neumann Whitening, and OLED Health Display | Build a hardware TRNG that uses reverse-biased B–E avalanche noise from a small-signal BJT, AC-coupled and amplified with a dual-stage rail‑to‑rail op-amp chain, digitized by a high-speed comparator, whitened in firmware (von Neumann), and monitored on an OLED for bias/monobit/run-length health tests. Output a continuous stream of true random bits over USB serial and show live entropy metrics. Analog and digital domains are cleanly partitioned; no soldering. | comparator, I2C, op‑amp, analog conditioning, OLED display, TDR | 3–4 |
| Breadboard Cable Fault Locator (Time‑Domain Reflectometer) for Coax (1–300 m) Using 74AC14 Edge Launch and Schmitt Detection | Build a compact TDR that launches a sub‑100 ns pulse into a coax cable and measures the round‑trip time of reflections to locate opens/shorts and major impedance discontinuities. A 74AC14 provides both a fast launch pulse and a high‑speed Schmitt detector. An Arduino Nano times the reflection using its 16‑bit timer and displays cable length on a 128×64 I2C OLED. Designed for 50 Ω coax (e.g., RG‑58) with a fixed velocity factor of 0.66. Resolution ~5–10 m, range ~1–300 m depending on cable attenuation. Completion time estimate: 3–4 hours | Schmitt trigger, I2C, OLED display, TDR, fast edges, display/UI | 3-4 |
| Breadboard Inductive Power and Data Link (125 kHz) with Resonant Coupling, ASK Backscatter Telemetry, and Dual MCUs | Build a two-board wireless power and telemetry link: a primary 125 kHz class‑D half‑bridge drives a resonant transmit coil; a secondary resonant receive coil rectifies power to 3.3 V to run a microcontroller. The secondary sends data back by load‑modulating (ASK backscatter) the coil; the primary envelope‑detects and decodes it. The primary can also send data downlink by amplitude shifting the drive. Demonstrates practical near‑field power transfer, resonant tuning, analog envelope detection, and digital framing. | TDR, fast edges, sensors | 4–6 |
| Breadboard Sensorless BLDC Motor Controller (12 V, 3‑Phase) with Back‑EMF Zero‑Crossing and Low‑Side PWM | Build a sensorless 3‑phase BLDC motor controller that uses analog back‑EMF zero‑crossing detection and a microcontroller for commutation and speed control. The high side uses P‑channel MOSFETs (static during each commutation sector), the low side uses N‑channel MOSFETs with PWM for torque/speed. Zero‑cross comparators reference the virtual half‑bus and trigger commutation with fixed digital deadtime. This project demonstrates mixed‑signal control loops, gate drive design, and robust analog sensing on a breadboard at 12 V. | comparator, PWM control, motor control, TDR, fast edges, sensors | 5 |
| Breadboard 4‑Electrode Conductivity Meter (1 kHz AC) with Synchronous Sampling and OLED Readout | A precision 4‑electrode conductivity meter for aqueous solutions using AC excitation at 1 kHz to avoid polarization errors. The drive channel generates a filtered PWM sine and applies it through a known series resistor; voltage across the solution is sensed with an instrumentation amplifier while current is measured via a shunt. An MCU samples both channels synchronously via an SPI ADC, performs digital lock‑in (multiply‑accumulate with the known reference), and displays conductivity (mS/cm), solution resistance (Ω), and temperature (°C) on an OLED. Designed for K = 1.0 cm⁻¹ cells and single‑supply 5 V operation with a rail‑splitter mid‑reference. All on breadboards, no soldering. | ADC, I2C, SPI, temperature sensing, PWM control, OLED display | 3–4 |