Light and IR
A photoresistor module on a dusk switch and a TCRT5000 reflective IR sensor: light as a voltage, a comparator with a threshold, and infrared that bounces off white and vanishes into black.
Open it in the simulatorAll paths
Sensors and measurement
Intermediate: thermistors and RTDs, strain gauges in a Wheatstone bridge, light and IR, current on a shunt and an INA219, ADC resolution and noise, and calibration, finished with a power instrument you check against Ohm's law.
0 of 7 done
What you will build
2 projects, built step by step
7 lessons in 3 chapters, about 4 hours on a simulated Arduino Uno R3. Free, in your browser, every step checked by the simulator.
Calibration
A kitchen scale on an HX711: the offset that tare removes, the gain error that only a known weight finds, a check at a second point, and the noise left over.
Open it in the simulatorThe map
Chapter by chapter
Each lesson opens when the one before it is done, and each chapter ends in a project.
Chapter 1
Sensing the world
Temperature, strain and light, each turned into a resistance or a voltage.
- Open218 XP
Thermistors and RTDs
A 10 k NTC bead on a meter and in a divider on A0: what "10 k" means, why the curve bends, how the divider turns ohms into volts, and when a platinum RTD is worth the money.
0 of 6 steps
- Locked218 XP
Strain gauges and the Wheatstone bridge
Four 350 ohm strain gauges in a Wheatstone bridge: how a 0.2% change becomes millivolts, why two or four active gauges beat one, and how the bridge cancels temperature.
0 of 6 steps
- ProjectLocked436 XP
Light and IR
A photoresistor module on a dusk switch and a TCRT5000 reflective IR sensor: light as a voltage, a comparator with a threshold, and infrared that bounces off white and vanishes into black.
0 of 6 steps
Chapter 2
Measuring it well
Current on a shunt, the limits of an ADC, and calibration against a known value.
- Locked218 XP
Current sensing with a shunt and an INA219
A battery gauge with an INA219: a 0.1 ohm shunt turns amps into millivolts, a meter reads the same millivolts, and a heavier load shows why time left falls faster than percent.
0 of 6 steps
- Locked187 XP
ADC resolution and noise
A 0 to 25 V voltmeter on an Uno: what 10 bits buy you, the smallest step it can see, what happens past the top of the range, and how averaging fights noise.
0 of 5 steps
- ProjectLocked436 XP
Calibration
A kitchen scale on an HX711: the offset that tare removes, the gain error that only a known weight finds, a check at a second point, and the noise left over.
0 of 6 steps
Chapter 3
Boss project
A power instrument checked against Ohm's law, with a latching trip.
- Locked249 XP
Boss: a calibrated power instrument
A bench supply monitor on an Uno and an INA219: volts, amps and watts checked against Ohm's law and the shunt, a second load, and an over-current trip that latches until RESET.
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Syllabus
Every lesson in the course
All 7 lessons, in order, each with what it covers. Any of them opens in the editor right away.
Sensing the world
- Thermistors and RTDsA 10 k NTC bead on a meter and in a divider on A0: what "10 k" means, why the curve bends, how the divider turns ohms into volts, and when a platinum RTD is worth the money.
- Strain gauges and the Wheatstone bridgeFour 350 ohm strain gauges in a Wheatstone bridge: how a 0.2% change becomes millivolts, why two or four active gauges beat one, and how the bridge cancels temperature.
- Light and IRA photoresistor module on a dusk switch and a TCRT5000 reflective IR sensor: light as a voltage, a comparator with a threshold, and infrared that bounces off white and vanishes into black.
Measuring it well
- Current sensing with a shunt and an INA219A battery gauge with an INA219: a 0.1 ohm shunt turns amps into millivolts, a meter reads the same millivolts, and a heavier load shows why time left falls faster than percent.
- ADC resolution and noiseA 0 to 25 V voltmeter on an Uno: what 10 bits buy you, the smallest step it can see, what happens past the top of the range, and how averaging fights noise.
- CalibrationA kitchen scale on an HX711: the offset that tare removes, the gain error that only a known weight finds, a check at a second point, and the noise left over.
Boss project
- Boss: a calibrated power instrumentA bench supply monitor on an Uno and an INA219: volts, amps and watts checked against Ohm's law and the shunt, a second load, and an over-current trip that latches until RESET.
Keep going
The next course on your track
Sensors and measurement is part of the electrical track, a ladder of courses from zero to expert.
Relays, contactors and motor control
Intermediate, the electrician's course: relay coils and flyback diodes, latching start/stop circuits, interlocks, three-way switching, timers and ladder logic, all at low voltage, finished with a start/stop station and an emergency stop you wire yourself.
Open the next courseElectrical track
Current and voltage you can see, then transistors, op-amps, filters, power and PCBs. Every circuit runs in a real circuit simulator in your browser.
See every course on the trackKits
Build it on your bench too
Every lesson runs in the simulator with nothing to buy. When you want the real thing, these kits have the parts.
Find your kit
Pick the starter kit you own and run every lesson in its manual with the same parts on the same pins.
See every kitQuestions
About Sensors and measurement
Is Sensors and measurement free?
Yes. All 7 lessons of Sensors and measurement are free and run in your browser, with nothing to install and no parts to buy before you start.
Do I need a real Arduino Uno R3?
No. Every lesson runs on a simulated Arduino Uno R3 with its parts on the canvas, and the simulator checks each step as you go. When you want to build it for real, the same wiring and code work on a real board.
How long does Sensors and measurement take?
About 4 hours: 7 lessons in 3 chapters, each one a few short steps. Your progress is kept, so you can stop after any lesson and pick up where you left off.
What will I build?
Each chapter ends in a project that puts it together: Light and IR and Calibration.
Where do I start?
With "Thermistors and RTDs", and each lesson builds on the one before it. New to circuits? Electronics basics is the course that starts from zero.