Every Sensor Explained in 7 Minutes
Ever wondered how your circuit actually knows what's happening in the real world? In this video I break down 8 of the most important sensors — Thermistor, Ultrasonic, PIR, Hall Effect, IMU, Piezoelectric, Gas/NDIR CO₂, and Capacitive Touch — so you can finally understand what's going on inside every device around you.
This video covers how each sensor works at a physical level, what it's actually measuring, and where you'll find it in real hardware — from your car's engine and your drone's motors to the screen you're touching right now. Whether you're just getting into electronics or want to finally understand the parts you've been using for years, this breakdown covers the fundamentals without drowning you in equations.
⏱️ Timestamps:
00:00 #1. Thermistor (Temperature Sensing)
01:12 #2. Ultrasonic (Distance Measurement)
01:53 #3. PIR (Passive Infrared Motion)
02:33 #4. Hall Effect (Magnetic Position Sensing)
03:21 #5. IMU (Accelerometer + Gyroscope + Fusion)
04:15 #6. Piezoelectric (Stress to Voltage)
04:41 #7. Gas Sensors & NDIR CO₂ (Gas Sensing)
06:01 #8. Capacitive Touch (How Touchscreens Work)
📚 References & Quick Reference
Thermistor
NTC — resistance drops as temperature rises
Use in a voltage divider → read with ADC
DS18B20 — digital, 1-Wire, ±0.5°C accuracy
Ultrasonic (HC-SR04)
TRIG — 10µs pulse to fire
ECHO — high pulse duration = round-trip time
Distance = 343 m/s × time / 2
PIR
Passive — no emission, detects IR from warm bodies
Two pyroelectric elements in differential config
Fresnel lens divides FOV into detection zones
Hall Effect
Output voltage proportional to magnetic field strength
Used in BLDC motor commutation (3 sensors × 120°)
Also: lid detection, crankshaft position, current sensing
IMU (e.g. MPU-6050)
Accelerometer — proof mass on MEMS springs, reads up to 3 axes
Gyroscope — Coriolis effect on vibrating structure, reads rotation rate
Fusion — complementary or Kalman filter combines both
Piezoelectric
Compress the material → voltage output
Apply voltage → physical deformation
Used for: knock sensing, microphones, haptics, ultrasound
Gas Sensors
MQ-series — metal oxide semiconductor, resistance drops in target gas
NDIR CO₂ — IR absorption at 4.26µm, no cross-sensitivity
Capacitive Touch
Mutual capacitance grid — rows driven, columns read
Finger disturbs coupling at intersection → coordinate calculated
Multi-touch capable, scans at 120Hz+
🔗 Recommended reading:
HC-SR04 datasheet: https://docs.arduino.cc/learn/built-i...
MPU-6050 overview: https://invensense.tdk.com/products/m...
Hall effect basics: https://www.electronics-tutorials.ws/...
PIR sensor guide: https://learn.adafruit.com/pir-passiv...
Piezoelectric fundamentals: https://www.piezo.com/tech1what.html
NDIR CO₂ sensing: https://www.sensirion.com/learn/co2-s...
Capacitive touch explained: https://www.azoteq.com/technology/cap...