A 180° servo moves to the angle you command and holds it; a 360° (continuous) servo cannot hold an angle at all — its write() value controls speed and direction instead. A 270° servo is simply a positional servo with a wider sweep. All three look identical from the outside, so below is a 30-second […]

If your ESP32 is not detected in Arduino IDE, the cause is almost always one of three things: a charge-only USB cable, a missing CH340 or CP2102 driver, or a board that needs its BOOT button held during upload. Swap to a proper data cable first — that one step fixes over half the cases […]

To solder header pins, push the header’s long side into a breadboard, sit the module on top, then touch a 350 °C iron to both the pad and the pin for 1–2 seconds while feeding solder into the joint — about 3 seconds per joint. A good joint looks like a shiny little volcano, and 15 […]

Your LM2596 buck converter ships at a random output — often 9V or 12V — and that is normal, not a defect. To set it to 5V, connect a 7–12V input to IN+/IN−, probe OUT+ and OUT− with a multimeter set to DC volts (the 20V range on manual meters), and slowly turn the trimmer […]

The Data Logging Shield gives an Uno a full-size SD socket and a DS1307 clock. Here is the wiring for a waterproof DS18B20, a compiled sketch that writes timestamped CSV rows, and the two mechanisms that decide whether your log survives a power cut: the SD library’s 512-byte RAM buffer, and the DS1307’s CH bit.

The GY-906 MLX90614 does not measure a point — it averages everything inside a 90° cone, so the spot it reads is twice as wide as its distance. Here is the wiring, a compiled sketch, the emissivity fix for shiny metal, and why this is not a fever thermometer.

A pulse sensor and a MAX30102 both measure light, not heartbeats. Wire both to one Arduino Uno, plot the raw PPG waveform with no library, read part ID register 0xFF to find out which die you actually have, and diagnose the silent I2C bus that makes a perfectly wired module invisible. Neither part is a medical device.

The TM1637’s two wires are not I2C, and the MAX7219’s three pins never grow no matter how many panels you chain. That asymmetry — plus what is actually in each bag — decides which 7-segment display your Arduino project should use.

A flame sensor feels no heat — it sees 760–1100nm infrared light. Wire the FLAME4P to a buzzer on an Arduino Uno, calibrate the LM393 threshold by measurement instead of guesswork, and know exactly where this classroom alarm’s limits are.

On the L298N, IN1 and IN2 choose direction and analogWrite() on ENA sets the speed. The catch: ENA ships with a jumper cap fitted, so nothing changes until you pull it off.