Electronics Introduction

  Ultrasonic ( HC-SR04 / waterproof transducers) Accuracy Add RC low-pass on echo (e.g., 1–4.7 kΩ + 100–470 pF) before the MCU to tame ringing. Time with a hardware timer input-capture ; average N readings, reject outliers with a median filter . Temperature-compensate sound speed: d = t ⋅ c ( T ) 2 ,    c ( T ) ≈ 331.3 + 0.606 T ° C   m/s d = \frac{t \cdot c(T)}{2},\; c(T)\approx331.3+0.606T_{°C}\,\text{m/s} d = 2 t ⋅ c ( T ) ​ , c ( T ) ≈ 331.3 + 0.606 T ° C ​ m/s Range Use a module with separate TX/RX transducers; add LNA (low-noise op-amp) on RX. Use narrow beam horns or foam baffles to reduce multipath. Slow down update rate and burst 8–16 pings , then correlate (coherent averaging) to dig out weak returns. Temperature (NTC, PT100 / PT1000 , IC like TMP117 ) Accuracy Excite NTC with constant-current (100–500 µA) to linearize ADC; use 4-wire for RTDs. Use a precision reference (≤0.05%) and 16–24-bit ΔΣ ADC for RTDs. Calibrate two-poi...

 For drone applications , both a gyroscope and an accelerometer are essential — and they’re typically used together in an IMU (Inertial Measurement Unit) . Here's how they work in a drone:  Why Both Are Needed in a Drone Sensor Role in a Drone Accelerometer Measures linear movement and tilt (e.g., helps detect up/down, forward/backward) Gyroscope Measures rotation rate (e.g., helps stabilize pitch, roll, yaw during flight) Together, they allow the drone to: Maintain stable flight Perform flips and turns Auto-correct position against wind or vibration Enable GPS-free hovering and indoor flight  Recommended Sensor: IMU Modules For drones, use a 6-axis or 9-axis IMU , which combines: 3-axis accelerometer 3-axis gyroscope (optional) 3-axis magnetometer for compass/heading  Popular IMUs for drones: Sensor Type Notes MPU6050 6-axis Very common, good for hobby drones MPU9250 9-axis Adds magnetometer for better heading ICM-20948 9-axis Hig...