2N2222A NPN General Purpose Transistor (TO-92)

2N2222A NPN General Purpose Transistor (TO-92) – Technical Specifications:

Component Type – NPN Bipolar Junction Transistor
Package – TO-92 Through-Hole
Collector-Emitter Voltage (Vceo) – 40V
Collector Current (Continuous) – 600mA
Power Dissipation – 625mW
DC Current Gain (hFE) – 100–300
Transition Frequency – 300MHz
Pin Order (flat face forward) – Emitter / Base / Collector

1: The 2N2222A switches current from Collector to Emitter based on a small Base current. Always use a Base resistor between your GPIO pin and the Base — 1kΩ for 5V logic, 330–470Ω for 3.3V logic (ESP8266/ESP32).

2: To use it as a clean ON/OFF switch, drive it into saturation by ensuring base current is at least 1/10th of the load current — under-driving wastes power as heat instead of switching cleanly.

3: When switching inductive loads such as relay coils or small motors, always add a flyback diode (e.g. 1N4007) across the load in reverse bias to protect the transistor from voltage spikes.

4: TO-92 pinout can vary by manufacturer — always verify Emitter/Base/Collector order against the datasheet before wiring, especially before committing to a PCB layout.

5: Rated for 600mA continuous — for higher current loads, step up to a TIP31C or a logic-level MOSFET such as the IRLZ44N.