2N3904 General Purpose NPN Transistor – KSH 5 at HIMASTORES Mombasa – best electronics in Kenya
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2N3904 General Purpose NPN Transistor

SKU: HMJ139 Category: Transistors
KSH 5.00
In Stock

Product Description

2N3904 General Purpose NPN Transistor

Low-Power NPN Switching and Amplification Transistor

The 2N3904 is a generalpurpose NPN bipolar junction transistor (BJT) designed for lowpower switching and amplification applications. It is one of the most popular and widely used transistors in hobby electronics, serving as a reliable choice for interfacing microcontrollers with relays, LEDs, and small motors.

GeneralPurpose NPN Transistor Ideal for switching loads up to 200mA.
ThroughHole TO92 Package - Standard breadboard and PCB compatible.
Collector current max: 200mA (continuous).
Collector-Emitter Voltage (VCEO): 40V.
For Arduino projects, use this transistor as a low-side switch with a base resistor (typically 1kΩ) to control loads like relays, buzzers, or LEDs.

Technical Specifications

ParameterValue
Transistor PolarityNPN
Continuous Collector Current (IC)200mA (max)
Collector-Emitter Voltage (VCEO)40V (max)
Collector-Base Voltage (VCBO)60V (max)
Emitter-Base Voltage (VEBO)6V (max)
Power Dissipation (PD)625mW (TO-92)
DC Current Gain (hFE)100 to 300
Transition Frequency (fT)300MHz
Package TypeTO-92

= Pin Configuration (Flat side facing you) =

PinNameDescription
1EmitterCurrent flows out through the emitter.
2BaseControls the transistor's switching.
3CollectorCurrent flows into the collector.

= Key Features =

+Low Power Switching - Handles loads up to 200mA at 40V.

+High Gain - DC current gain (hFE) up to 300 ensures strong current amplification.

+HighSpeed Switching 300MHz transition frequency for fast applications.

+Complementary PNP Part Use with 2N3906 for pushpull circuits.

= Applications =

  1. Switching loads (LEDs, relays, buzzers) from microcontrollers.
  2. Low-power audio amplifier circuits.
  3. Logic level shifting and signal inversion.
  4. General-purpose switching and amplification tasks.
Popular and Reliable - A standard transistor in electronics.
Easy to Use Throughhole TO-92 package for breadboard prototyping.

√ Compatible with 3.3V and 5V logic levels.

√ Works with Arduino, ESP32, and Raspberry Pi.

√ Low-cost and widely available.

Troubleshooting

Transistor not switching:

  • Verify base resistor value (typically 1kΩ to 10kΩ).
  • Check emitter, base, and collector connections.
  • Ensure base voltage is >0.7V for turn-on.

Excessive heat:

  • Verify load current is below 200mA.
  • Use a heatsink or transistor with higher power rating.