BC337 transistor - NPN bipolar, 45 V, 0.8 A, TO-92

Product overview

• NPN bipolar transistor with a breakdown voltage of up to 45 V
• Maximum current of up to 0.8 A
• Low base current required, making it suitable for 3.3 V logic
• Standard TO-92 package for direct use on perforated boards or breadboards
• Easy control of loads such as LEDs, relays, or small motors

Product description

The BC337 is an NPN bipolar transistor in a standard package, primarily used for switching and amplifying circuits with manual or digital control signals. It is used wherever a microcontroller output cannot drive an external load directly and therefore requires an amplifier transistor.

The operating principle is simple: a small base current opens the path for a larger current flow from the collector to the emitter. With a breakdown voltage of up to 45 V, the component can also withstand higher supply voltages in industrial and hobby applications, while the maximum current of 0.8 A is sufficient for small loads. The low base current required means that the transistor can be connected directly to 3.3 V logic without the need for level shifting.

Typical applications include switching individual LEDs or LED strips via a series resistor, controlling smaller relays or solenoid coils, and controlling slow DC motors with a few hundred milliamps. In practice, the transistor is often used to interface digital logic with a 12 V load, for example when switching a valve or reducing brightness via PWM signals.

For safe operation, the base resistor must be calculated so that the transistor operates in switching mode and does not overheat. A transistor datasheet or an online calculator can help with this. For coils and relays, a flyback diode must be connected in parallel with the load to suppress the inductive voltage spike when switching off. The collector operating voltage must not exceed 45 V.

Safety notice

Incorrect wiring or overloading can cause the component to become hot or burn out. The component is intended exclusively for building prototypes and for testing and development purposes. When controlling consumers connected to household mains, consult a qualified electrician.

Scope of delivery

• 1x BC337 NPN bipolar transistor, 45 V, 0.8 A, TO-92