2N3904 Transistor Datasheet, Equivalent, and Pinout

2N3904 Transistor

This article will introduce you to the pinout, model, Introduction, features, specifications, applications, equivalent, and dimensions of the 2N3904 transistor. We also provide you with a 2N3904 Datasheet pdf.

2N3904 Model

2N3904 Introduction

The 2N3904 transistor is a bipolar negative-positive-negative (NPN) transistor usually suitable for negative ground circuits. It can be used for audio signals and medium-speed switching applications. This small transistor is the counterpart of the 2N3906 transistor, a positive-negative-positive (PNP) transistor. A larger collector current can be generated by injecting a small base current into the 2N3904 transistor.

The 2N3904 transistor has three terminals: an emitter, base, and collector. The emitter and collector are the main terminals of the 2N3904 transistor. Depending on the circuit configuration, a load or equivalent load can be connected to the emitter or collector.

The various parameters of the 2N3904 transistor are referred to as β or current gain, which is the ratio of collector current to base current. For a current gain of 100, a change in base current of 0.001 amps (a) results in a change of 0.1 amps at the collector.

This illustrates how the 2N3904 transistor is an amplifier. A small change in base current results in a hundredfold change in collector current, which can be translated into voltage or power changes.

The bias is the idle current at the transistor terminals. 

Generally, the 2N3904 transistor requires a positive bias from the base to the emitter, which means a positive potential on the substrate for the emitter. It should be noted that the substrate is a positive (P) type material, and the emitter is a negative (N) type material. The amount of positive bias must be controlled for the specific application. Too much positive bias will usually result in too much collector current, which usually leads to saturation.

Therefore when the base pin is grounded, the collector and emitter will remain open (reverse bias) and will close (forward bias) when a signal is supplied to the base pin.

The gain value of the 2N3904 is 300; This value determines the amplification capability of the transistor. The maximum current that can flow through the collector pin is 200mA, so we cannot use this transistor to connect a load that consumes more than 200mA. To bias the transistor, we must supply current to the base pin, which should be limited to 5mA.

When the 2N3904 is fully biased, it allows a maximum current of 200mA to flow through the collector and emitter. This phase is called the saturation zone, and the typical voltages allowed for collector-emitter (VCE) or collector-base (VCB) are 40V and 60V, respectively. when the base current is removed, the transistor is completely turned off, and this phase is called the cutoff zone.

2N3904 Transistor Pinout

Pin Configuration

Number	Name	Description
1	Emitter	Current Drains out through emitter
2	Base	Controls the biasing of transistor
3	Collector	Current flows in through collector

2N3904 Transistor Features

• Low current, Low voltage. 

• Bipolar negative-positive-negative (NPN) transistor

• DC Current Gain (hFE): 100 to 300

• Continuous Collector Current (IC) of 200mA.

• Base-emitter voltage (VBE) is 6 V.

• Collector Current: 0.2 A.

• Collector-emitter voltage (VCE) is 40V.

• Collector-Base Voltage (VCB) is 60V.

• Package(THT): TO-92

2N3904 Specifications

2N3904 Application

• Commonly used in home appliances such as TVs

• It can be used to control voltage loads up to 40V

• It can be used for audio signals and medium-speed switching

• Driver modules, such as relay drivers, LED drivers, etc...

• Amplifier modules, such as audio amplifiers, signal amplifiers, etc...

2N3904 Transistor Equivalent

BC537, BC538, BC549, BC639, P2N2222A, and 2N2369, 2N3055, 2N3906 where BC537 and BC538 are functionally equivalent transistors.

2N3904 Transistor Dimensions

For more information, please refer to 2N3904 Datasheet.

2N3904 Transistor Datasheet Download

Frequently Asked Questions

• What is the difference between 2N3904 and 2N2222?

The 2N2222 is in a TO-18 metal package, while the 2N3904 is in a TO-92 plastic package. The collector current of the 2N3904 is 200mA, while the collector current of the 2N2222 is close to 1 amp, which means that the 2N2222 can handle higher operating collector currents.

• Can I use the BC547 instead of the 2N3904?

The collector current of BC547 is 100mA, and the collector current of 2N3904 is 200mA. If you drive a load less than 100mA, you can replace 2N3904 with BC547, but not if you drive a load greater than 100mA.

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