2N3904 NPN Transistor – General Purpose Low-Power Switch & Amplifier (TO-92 Package)
The 2N3904 is a widely used NPN bipolar junction transistor (BJT) suitable for low-power switching and signal amplification. Ideal for analog, digital, and embedded circuits, it is commonly used in Arduino projects, sensor circuits, and audio applications. Its TO-92 through-hole package makes it easy to prototype and integrate into PCBs.
 
Key Features:
NPN Transistor
Allows current flow from collector to emitter when the base is high—commonly used for switching and amplifying signals.
Collector Current up to 200 mA
Can drive LEDs, buzzers, relays, and other small loads.
High Switching Speed
Suitable for high-speed switching applications and digital logic circuits.
Low Noise Operation
Provides stable performance in analog circuits and audio applications.
Compact TO-92 Package
Ideal for breadboarding and through-hole circuit designs.
 
Applications:
Low-power switching circuits
Signal amplification in analog and audio circuits
Microcontroller-based control systems
Logic-level switching
DIY electronics and educational kits
Complementary use with 2N3906 (PNP)
 
Package Includes:
1 × 2N3904 NPN Transistor 
 
Specifications:
Transistor Type: NPN
Max Collector Current (Ic): 200 mA
Collector-Emitter Voltage (Vce): 40 V
Collector-Base Voltage (Vcb): 60 V
Emitter-Base Voltage (Veb): 6 V
DC Gain (hFE): 100 to 300
Transition Frequency: 300 MHz
Package Type: TO-92
Mounting Type: Through-hole
 
Dimensions:
Body Length: 5 mm
Body Width: 4 mm
Lead Length: 14 mm
 
Weight:  0.2 g
 
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Shipping Weight = 20 grams