What Is the BAT85? Schottky Signal Diode and Uses
What is the BAT85 Schottky signal diode? 30V/200mA, ~0.4V drop, detector/low-loss, how it differs from the 1N4148 and alternatives (BAT54, BAT43, 1N5711).
What Is the 1N5822? 3A Schottky Diode and Uses
What is the 1N5822 Schottky diode? 40V/3A, ~0.5V drop, buck catch diode, how it differs from the 1N5819 and alternatives (SR360, MBR340).
What Is the 1N4733? 5.1V Zener Diode and Uses
What is the 1N4733 Zener diode? 5.1V/1W, series resistor, voltage reference/protection, the 1N47xx family and alternatives (1N4740, BZX55, TL431).
What Is the 1N5408? 3A Rectifier Diode and Uses
What is the 1N5408 rectifier power diode? 1000V/3A, medium-power rectification, how it differs from the 1N4007 and alternatives (1N5404, 6A10, 1N5822).
What Is the 1N4001? Rectifier Diode (50V) and Uses
What is the 1N4001 rectifier diode? 50V/1A, the 1N400x family, rectification/protection, how it differs from the 1N4007 and alternatives (1N4004, UF4001, 1N5819).
What Is the IRF540N? 100V N-Channel Power MOSFET: Pinout and Uses
What is the IRF540N N-channel power MOSFET? Pinout (TO-220 G-D-S), 100V/33A, standard-level warning, how it differs from the IRFZ44N and alternatives (IRL540N, IRF640).
What Is the IRLZ44N? Logic-Level MOSFET: Pinout and Uses
What is the IRLZ44N logic-level N-channel MOSFET? Pinout (TO-220 G-D-S), 5V drive, how it differs from the IRFZ44N and alternatives (IRLB8721, IRL540N).
What Is the 2N7000? Small N-Channel MOSFET: Pinout and Uses
What is the 2N7000 small-signal N-channel MOSFET? Pinout (TO-92 S-G-D), logic level, level shifting and alternatives (BS170, 2N7002, IRLZ44N).
What Is the BC557? PNP Transistor: Pinout (C-B-E) and Uses
What is the BC557 PNP transistor? Pinout (TO-92 C-B-E), complement of the BC547, A/B/C grades and alternatives (BC558, 2N3906).
What Is the 2N3906? PNP Transistor: Pinout and Uses
What is the 2N3906 PNP transistor? Pinout (TO-92 E-B-C), complement of the 2N3904, high-side switching and alternatives (2N2907, BC557).
What Is the WS2812B (NeoPixel)? Addressable RGB LED and Uses
What is the WS2812B (NeoPixel) addressable RGB LED? 4 terminals, single-wire protocol, 5V/current, capacitor+330Ω, libraries and alternatives (WS2811, SK6812, APA102).
What Is the PC817? Optocoupler: Pinout, Isolation and Uses
What is the PC817 optocoupler (opto-isolator)? Pinout (DIP-4), ~5000V isolation, CTR, input resistor, SMPS/TL431 and alternatives (EL817, PC827, 4N35).
What Is the MAX7219? Serial LED Driver: 7-Segment/Matrix and Uses
What is the MAX7219 serial LED display driver? 8-digit 7-segment / 8×8 matrix, SPI-like, single Rset, chaining, how it differs from the 74HC595 and alternatives (MAX7221, HT16K33, TM1637).
What Is the HD44780? Character LCD Controller: Pinout and Uses
What is the HD44780 character LCD controller? 16-pin interface, contrast (V0), 4/8-bit, I2C backpack (PCF8574) and alternatives (KS0066, SSD1306).
What Is the SSD1306? OLED Display Controller: Wiring and Uses
What is the SSD1306 OLED display controller? I2C/SPI wiring, 128×64, address 0x3C, libraries, how it differs from the SH1106 and alternatives (ST7789, HD44780).
What Is the PCF8574? I2C I/O Expander: Pinout and Uses
What is the PCF8574 I2C I/O expander? Pinout (DIP-16), 8 GPIO, addressing, quasi-bidirectional, LCD backpack and alternatives (PCF8575, MCP23017).
What Is the DS1307? Basic I2C RTC: Specs and Uses
What is the DS1307 basic I2C RTC? External crystal, 56B NVRAM, accuracy limit, how it differs from the DS3231 and alternatives (DS1302, PCF8563).
What Is the DS3231? High-Precision RTC: Specs and Uses
What is the DS3231 high-precision I2C RTC? TCXO, ±2 ppm, alarms/temperature, how it differs from the DS1307 and alternatives (DS3232, PCF8563).
What Is the MAX485? RS-485 Transceiver: Pinout and Uses
What is the MAX485 RS-485 transceiver? Pinout (DIP-8), DE/RE direction control, A/B differential, how it differs from the MAX232 and alternatives (MAX3485, SN75176).
What Is the MAX232? RS-232 Level Converter: Pinout and Uses
What is the MAX232 RS-232 level converter? Pinout (DIP-16), 4 capacitors/charge pump, TTL↔RS-232, how it differs from the MAX3232 and alternatives (MAX485).
What Is the MPU6050? 6-Axis IMU (Accel+Gyro): Specs and Uses
What is the MPU6050 6-axis IMU? I2C (0x68), ±g/±°/s ranges, GY-521, fusion/DMP, the 9-axis difference and alternatives (MPU9250, BNO055, ADXL345).
What Is the HC-SR04? Ultrasonic Distance Sensor: Calculation and Uses
What is the HC-SR04 ultrasonic distance sensor? Pinout (Trig/Echo), the distance formula, 2–400 cm, a 3.3V warning and alternatives (HC-SR04P, VL53L0X).
What Is the DHT22 (AM2302)? Temperature and Humidity Sensor and Uses
What is the DHT22 (AM2302) temperature+humidity sensor? Range (−40…80 °C, 0–100 %), how it differs from the DHT11 and alternatives (AM2302, SHT31, BME280).
What Is the DHT11? Temperature and Humidity Sensor: Specs and Uses
What is the DHT11 temperature+humidity sensor? Range (0–50 °C, 20–90 %), single-wire read, how it differs from the DHT22 and alternatives (AHT10, SHT31, BME280).
What Is the DS18B20? 1-Wire Digital Temperature Sensor and Uses
What is the DS18B20 1-Wire digital temperature sensor? Pinout (TO-92), 4.7k pull-up, −55…+125 °C, multiple sensors and alternatives (DS18S20, LM35, DHT22).
What Is the DRV8825? Stepper Driver: 1/32 Microstepping and Uses
What is the DRV8825 bipolar stepper driver? 1/32 microstepping, ~2.5A, 8.2–45V, STEP/DIR, how it differs from the A4988 and alternatives (TMC2209, TB6600).
What Is the A4988? Stepper Driver: Microstepping, Vref and Uses
What is the A4988 bipolar stepper driver? Microstepping (1/16), STEP/DIR, Vref current setting, 8–35V, how it differs from the DRV8825 and alternatives (TMC2208, DRV8834).
What Is the ULN2003? 7-Channel Darlington Array: Pinout and Uses
What is the ULN2003 Darlington driver array? Pinout (DIP-16), COM flyback, 500mA/channel, driving the 28BYJ-48 stepper, how it differs from the ULN2803 and alternatives (TIP120).
What Is the L293D? H-Bridge with Built-in Diodes: Pinout and Uses
What is the L293D dual H-bridge motor driver? Pinout (DIP-16), built-in flyback diodes, 600mA, how it differs from the L298N and alternatives (SN754410, TB6612FNG).
What Is the L298N? Dual H-Bridge Motor Driver: Specs and Uses
What is the L298N dual H-bridge motor driver? 2A/channel, 46V, IN/EN control, voltage drop/heat, how it differs from the L293D and alternatives (TB6612FNG, DRV8871).
What Is the STM32F103C8 (Blue Pill)? 32-bit ARM MCU and Uses
What is the STM32F103C8T6 (Blue Pill)? 32-bit Cortex-M3, 72 MHz, 64KB flash, USB/CAN, 5V tolerance, how it differs from the ATmega328P and alternatives (F401/F411, RP2040).
What Is the ESP32? WiFi + Bluetooth MCU: Specs and Uses
What is the ESP32? Dual core, WiFi + Bluetooth, GPIO/ADC/DAC/touch, 3.3V, versions (WROOM/S3/C3), how it differs from the ESP8266 and uses.
What Is the ESP8266? WiFi MCU: Specs, 3.3V and Uses
What is the ESP8266 WiFi microcontroller? Specs, 3.3V warning, current/supply, modules (ESP-01/12E/NodeMCU), how it differs from the ESP32 and uses.
What Is the ATtiny85? 8-Pin AVR: Pinout, Specs and Uses
What is the ATtiny85 8-pin AVR microcontroller? Pinout, 8KB flash, 6 GPIO, ADC/PWM, Arduino programming and alternatives (ATtiny13/45/84, ATmega328P).
What Is the ATmega328P? Arduino's MCU: Specs and Uses
What is the ATmega328P (Arduino Uno/Nano MCU)? 8-bit AVR, 32KB flash, GPIO/ADC, peripherals, functional pinout and alternatives (ATtiny85, ATmega2560, STM32F103C8).
What Is the CD4017? Decade Counter: Pinout, Operation and Uses
What is the CD4017 decade counter/divider? Pinout (16 pins, scattered outputs), CLK/Reset/Carry, an LED chaser (with a 555), frequency division and alternatives (CD4022, 74HC4017).
What Is the 74HC595? Shift Register: Pinout, Operation and Uses
What is the 74HC595 shift register? Pinout (16 pins), 8+ outputs from 3 pins, latch/daisy-chain operation, driving LEDs/7-segments and alternatives (74HC164, 74HC165, TPIC6B595).
What Is the 1N5819? Schottky Diode: Low Loss and Uses
What is the 1N5819 Schottky diode? Specs (40 V, 1 A, ~0.45 V drop), buck catch-diode use, how it differs from the 1N4007 and alternatives (1N5817/18, SS34, SB560).
What Is the 1N4007? Rectifier Diode: The 1N400x Family and Uses
What is the 1N4007 rectifier power diode? Specs (1000 V, 1 A), the 1N400x family table, rectification/protection uses, how it differs from the 1N4148 and alternatives (UF4007, 1N5408, 1N5819).
What Is the 1N4148? Fast Signal Diode: Specs and Uses
What is the 1N4148 small-signal / fast-switching diode? Specs (100 V, 200 mA, ~4 ns), cathode marking, uses, how it differs from the 1N4007 and alternatives (1N914, BAT85).
What Is the IRFZ44N? N-Channel Power MOSFET: Pinout and Uses
What is the IRFZ44N N-channel power MOSFET? Pinout (TO-220 G-D-S), 55V/49A, low RDS(on), a 'not logic-level' warning and alternatives (IRLZ44N, IRF3205, IRF540N).
What Is the TIP120? NPN Darlington: Pinout and High-Current Drive
What is the TIP120 NPN Darlington power transistor? Pinout (TO-220 B-C-E), 5A drive, hFE>1000, internal diode, heat and alternatives (TIP122, IRFZ44N, ULN2003).
What Is the BC547? NPN Transistor: Pinout (C-B-E) and Uses
What is the BC547 NPN transistor? Pinout (TO-92 C-B-E, the reverse of the 2N3904), A/B/C gain grades, switch/amplifier use and alternatives (BC548, BC557, 2N3904).
What Is the 2N3904? NPN Transistor: Pinout (E-B-C) and Uses
What is the 2N3904 NPN transistor? Pinout (TO-92 E-B-C), 200 mA, hFE, the pinout difference vs the BC547, switch/amplifier use and alternatives (2N3906, 2N2222, BC547).
What Is the 2N2222? NPN Transistor: Pinout, Specs and Uses
What is the 2N2222 (2N2222A) NPN transistor? Pinout (TO-92 vs TO-18), 800 mA switching, hFE, switch use and alternatives (2N3904, BC547, 2N2907).
What Is the TL431? Adjustable Voltage Reference: Terminals and Uses
What is the TL431 precision shunt voltage reference? Cathode/Anode/Reference terminals, 2.5–36 V programming (V=Vref(1+R1/R2)), SMPS feedback and alternatives (LM431, TL432, LM4040).
What Is the LM2596? Buck (Step-Down) Regulator: Pinout and Uses
What is the LM2596 switching buck regulator? Pinout (5 pins), efficiency, external parts (inductor, Schottky diode), ripple and alternatives (LM2576, MP1584, 7805).
What Is the AMS1117? 3.3V LDO Regulator: Pinout and Uses
What is the AMS1117 LDO regulator? Pinout (SOT-223), producing 3.3V, dropout (~1.1 V), output capacitor, heat and alternatives (LD1117, MCP1700, LM2596).