2N3904 NPN transistor - 40 V, 0.2 A, TO-92
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Pay in 30 days
Pay in 30 days
Description
Product overview
- NPN transistor for switching applications up to 40 V reverse voltage
- Collector current up to 200 mA
- Typical gain factor (hfe) of 100 to 200
- Current-controlled switch for logic outputs, LEDs, and small loads
- TO-92 package, three leads for easy mounting on perforated circuit boards
Product description
The 2N3904 is an NPN transistor in a TO-92 plastic package and is primarily used as a switching amplifier for low to medium currents. With a maximum reverse voltage of 40 V and a collector current of 200 mA, it operates reliably in prototype applications with logic levels between 5 V and 3.3 V.
The component functions as a current-controlled switch. A small base current opens or closes the path from the collector to the emitter. The typical gain factor (hfe) of 100 to 200 means that a base current of only a few milliamperes is sufficient to switch collector currents in the double-digit milliampere range. This makes the transistor particularly valuable as a driver between microcontroller outputs and current-consuming loads.
Typical applications include driving LEDs through a series resistor, switching DC motors in robotics projects, or amplifying sensor signals. The 2N3904 is also suitable as a fast switch in audio preamplifiers or for driving relay coils through a current-limiting resistor. In project builds, a single transistor can replace an IC, thereby reducing component costs.
The transistor requires no power supply other than the supply for the circuit being switched. A current-limiting resistor is always required for the base, as logic outputs cannot drive it directly. The 40 V reverse voltage prohibits use with mains voltages or high-voltage sources. In addition, a flyback diode is required when switching inductive loads such as coils or motors to absorb voltage spikes.
Safety information
This component is not suitable for operation with mains voltages or for integration into household electrical circuits. It is intended exclusively for building prototypes and for testing and development purposes in the laboratory. When designing the circuit, observe the correct pin assignment (collector, base, emitter), and if anything is unclear, seek advice on safe operation before commissioning.
Scope of delivery
- 1x 2N3904 - NPN transistor, 40V, 0.2A